Design of a Pico-hydro system to electrify rural villages in North East India

B C U

B E n g M e c h a n i c a l E n g i n e e r i n g

T h i r d Y e a r

U n d e r g r a d u a t e P r o j e c t -

S u p e r v i s o r : P r o f . M i c h e a l

W a r d

S t u d e n t I D : S 1 1 7 3 6 6 0 9

8 / 5 / 2 0 1 5

Mohammed Ouji

Contents

Abstract ................................................................................................................................................... 3

Problem statement ................................................................................................................................... 3

Scope ....................................................................................................................................................... 4

Chapter one ............................................................................................................................................. 5

Introduction ......................................................................................................................................... 5

Rationale ............................................................................................................................................. 7

Aim ..................................................................................................................................................... 7

Objectives ........................................................................................................................................... 7

Methodology ....................................................................................................................................... 8

Research methodology .................................................................................................................... 8

Design methodology ....................................................................................................................... 9

Chapter two – Country profile .............................................................................................................. 10

India .................................................................................................................................................. 10

Socioeconomic factors ...................................................................................................................... 11

North East India ................................................................................................................................ 12

Climate .......................................................................................................................................... 12

Economy ....................................................................................................................................... 14

Living standards ............................................................................................................................ 16

Summary ........................................................................................................................................... 19

Outcome ............................................................................................................................................ 20

Chapter three – Rural electrification ..................................................................................................... 21

Current state of rural electrification .................................................................................................. 21

Options .............................................................................................................................................. 24

Renewables ................................................................................................................................... 24

Non-renewable .............................................................................................................................. 29

Impact of rural electrification ........................................................................................................... 30

Summary ........................................................................................................................................... 33

Outcome ............................................................................................................................................ 33

Chapter four – Hydro-power ................................................................................................................. 33

Why Pico hydro?............................................................................................................................... 35

Principles of Pico hydro-power......................................................................................................... 36

Fluid dynamics .............................................................................................................................. 38

Basic components ......................................................................................................................... 44

Types of Pico-hydro schemes ....................................................................................................... 48

Summary ........................................................................................................................................... 50

Outcome ............................................................................................................................................ 51

Chapter five – Design ........................................................................................................................... 51

Design requirements ......................................................................................................................... 51

Turbine selection ............................................................................................................................... 52

Design Idea ....................................................................................................................................... 56

Cost considerations ........................................................................................................................... 58

CAD modelling and 3D printing ....................................................................................................... 60

Testing methodology ........................................................................................................................ 61

Summary ........................................................................................................................................... 62

Chapter six – Discussion ....................................................................................................................... 63

Discussion.......................................................................................................................................... 63

Chapter seven – Conclusions and recommendations ........................................................................... 64

Conclusion ........................................................................................................................................ 64

Recommendations ............................................................................................................................. 64

References ............................................................................................................................................. 65

Abstract

In this report a Pico-hydro Pelton wheel design is developed by: (1) studying the socio-economic

background of Northeast India such as climate, economy, and the living standards; (2) research of

sources of electrification and their individual capabilities in the Northeast Region (NER); and (3) the

foundations of Pico-hydro systems including the typical components and schemes. This is done by

obtaining information from census data, Government websites, past reports, journals and articles; and

henceforth critically analysing the information to eliminate waffle material and produce relevant

material. Following the literature review, a list of design requirements is defined and the design is

modelled according to the PDS. From this, a 3D printed Pelton wheel is fabricated.

Problem statement

Energy Deficiency - More than 68% of the total population of India live in rural areas.

According to The World Bank (2013), India is the 36th

most rural country in the world. As of

2014, there are a total of more than 590,000 inhabited villages existing in India: 19,000 of

which are un-electrified. More than one million homes in India have no lighting (Rural:

897,000; Urban: 267,000). Meanwhile, more than 77 million Indian homes use kerosene

lamps as their primary source of lighting; while 990,000 homes use coal, lignite, and oil.

India has vast potential in solar, wind, and small hydropower, nevertheless only thirty percent

of electricity is produced using renewable energy, while fifty-nine percent is produced by

coal. (World Bank, 2014)

Gridding Complications - Grid extension into rural areas is an expensive ordeal as the grid

may need to cover many miles before reaching the households: this increases the wiring cost

and the arrangement of the many electric pylons required to build the transmission network.

This requires a substantial amount of planning and preparation making it a labour intensive

and financially demanding venture. Even after placing the effort to grid a rural stretch, these

regions have fewer consumption of electricity per person than in urban areas: making such a

scheme hugely uneconomical. In addition to this, maintenance and operation of the grid poses

more problems due to its inaccessible location.

Large Scale hydro - The environmental impact of large scale hydro is profound. Large scale

hydro projects produce a vast amount of electricity; however they require large amount of

land space to be flooded. This leads to the displacement of villages, businesses, and cultural

sites; as well as ecological changes such as the loss of certain species of fish and the

subsequent disruption of the food chain. Tourists and locals also complain about the visual

and sound pollution that hydro dams have on the scenery of certain locations.

Nevertheless, studies conducted by the Independent Evaluation Group, 2008 have shown that

rural electrification boosts morale, provides people with a sense of security, and enhances

productivity and learning as well as giving access to information, healthcare and

entertainment. As a consequence this will speed up development and improve the local and

national GDP growth. Implementing small scale hydro systems to electrify rural Indian

villages will therefore significantly improve the life quality of a rural population, without the

drawbacks of large scale hydro and gridding.

Scope

This project will focus its interests on two parts specifically: the research of the potential of

hydro power in North East India; and the design of a Pico hydro system to work in N.E.

India. The research phase is also split into two parts: Researching the climate, economy,

agriculture and the living standards of the North Eastern states; and applying this knowledge

to state why electrification will benefit these states. The second phase is the exploration of

Pico hydro power including its core principles; the different schemes used worldwide; and its

development throughout the span of twenty years. A brief summary of other useful methods

of electrification such as solar, wind and so on will also be discussed and compared against

Pico hydro power. Finally, an assessment of the load bearing capability of the system will be

conducted against what Indian villagers view as essential appliances such as lighting, TV,

radio, mobile phone charger and a fan.

This report will be constrained to the design of the Pico hydro system only. Following Pugh’s

total design methodology, the design phase is split up into market research, specification,

concept design, detail design, manufacture and the sale of the product. The implementation of

the system will be covered in the recommendations briefly. It will cover the total cost (land

cost, financial cost) of placing the finished design in a rural Indian village.

Chapter one

Introduction

Electricity is vital for completing everyday activities, is a catalyst to learning and allows income

generation in rural areas. It is a necessary, but insufficient step towards economic development: it

must be complemented by socio-economic integration (Kamalapur, 2011). India’s demand for

electricity is enormous and is expected to grow over coming years. By 2020 it is estimated that India’s

power requirements may exceed 400,000 MW (Sharma et al, 2012). In its current state the country has

severe energy shortage as well as constant power outages. In some regions this power outage lasts 12

hours a day (Rao, 2013). In addition to this a large percentage of households use kerosene as their

primary light source, and wood as cooking fuel. This has adverse effect on health and takes up a

significant portion of their income. In a nation with 20% of population below poverty line, access to

energy must be provided to everyone in order to alleviate poverty and grow as an economy.

Renewable energy is one way to solve this energy crisis. Solar, wind and hydropower are proven

technologies that have been implemented worldwide to electrify even the most remote settlements. In

addition to this utilizing renewable energy in rural electrification could reduce up to 99% of Carbon

Dioxide (CO2) emissions (Frauke et al, 2009). India is known for its use of hydroelectric power with

more than 20% of its national electricity coming from this clean and abundant resource. India has a

combined potential of over 84,000MW at 60% load factor which is one of the best in the world

(Sharma et al, 2012). Micro and Pico hydro-power in particular are the most cost effective option for

electrifying rural areas in India (Lahimer et al, 2012; Maher, 2002). Pico-hydro (<5kWe) is especially

cost effective in remote rural areas and has already proven itself in many developing countries such

as Kenya, Mozambique, Tanzania, Lao PDR, Philippines, Nepal, Sri Lanka, and Colombia (Ahlborg,

2014, 2015; Arriaga, 2010; Bekele, 2012; Borhanazad, 2013; Dorji, 2012; Martin, 2014; Mainali,

2012). Entire Nepalese towns are lit thanks to Pico-hydro power and further research on making this

resource widely available will mean more locations around the world will benefit from it (Lahimer et

al, 2012).

The Government of India have set up several initiatives to bridge the gap between rural and urban

energy access, albeit with a small success rate. Government initiatives such as RGGVY; JNNSM;

Electricity Act 2003; NEP, 2005; NTP, 2006; and NREP, 2006 were started to encourage

development of rural electrification; however due to resource limitations, poor planning, delays and

vagueness with respect to policies, shortcomings in programmes and poverty, India has failed to meet

their initial target of full household electrification by 2012 (Kamalapur,2011; Sharma et al, 2012;

Balachandra, 2011). RGGVY aims specifically to electrify Below Poverty Line (BPL) households but

disregards Above Poverty Line (APL) households. The government of India classifies a village as

electrified if only 10% of households have access to electricity. An assessment carried out by

P.Balachandra on the energy access of different income classes and regions found that successful

states (Punjab, Tamil Nadu) had 3 times more electricity access than failure states (Assam, West

Bengal, Bihar). This study also suggests annual growth rates for rural access have actually decreased

from double digits in 1991 to only about 4%. It can be said therefore that current policies should be

reviewed and a radical new action needs to be implemented by the Government to provide fair and

equal share of energy access to all regions of India.

One of the key issues in rural electrification is the disparity of settlements which makes grid extension

into remote areas difficult. Bambawale, 2010 suggests that prior to deciding between gridding or

decentralizing a certain region, the socio-economic and geographic information must be obtained. For

this reason a comprehensive country profile of India has been produced detailing the socio-economic

factors of Northeast India.

Rationale

One the key issues in developing countries, including India, is a shortage of electricity

supply. The author believes that electricity should be a common commodity however a

majority of Indian population have no access to electricity. Electricity is a catalyst to poverty

alleviation, welfare improvement and economy growth. The rationale of this project is to

make the reader aware of the energy crisis, and to increase their knowledge of why rural

electrification is important to the lives of millions. In addition, it is intended to increase the

reader’s understanding of Pico-hydro power and its principles. Ultimately, the purpose of this

report is to guide and motivate the reader to contribute to the cause and innovate the field of

rural electrification.

Aim

To design a Pico-hydro power system to electrify rural villages in Northeast India

Objectives

Conduct research on India in order to gain understanding of socio-economic dynamics

of Northeast region (NER)

Develop ideas on how to best approach rural electrification by investigating potential

of renewable and non-renewable energy resources in the region

Acquire in-depth knowledge on the principles, components and types of schemes of

Pico-hydro systems using books, journals and past reports

Consider design aspects of the pico-hydro system and design to meet the needs of the

local population based on the literature review

Design, using CATIA software, Pelton wheel used in the Pico-hydro scheme

Utilize 3D printing technology to print the CAD model and realize the design

Methodology

Research methodology

Initially, background research on the subject is studied, leading to a more refined view of the

topics which are split into:

socioeconomic factors in rural India,

Pico hydro power and

fluid dynamics

The topics were directly linked to minimise irrelevant “waffle” material. The initial review

was conducted on online articles, peer reviewed past reports, and journals which fed in

relevant information about the topics. Qualitative data relating to the socioeconomic factors

was obtained using the Indian Government websites and the World Bank. Quantitative and

qualitative data regarding the principles of Pico hydroelectric power and fluid dynamics are

obtained via books, reports, and journals.

Consequently, the information learnt is applied into the literature review section which gives

a detailed view of the past work conducted on the subject of electrification of rural areas. The

literature review is conducted on a reasonable sample (25) of past reports which compares

and contrasts the past work covered in other studies in the same subject. For quality of

information, reports more than ten years old are not included.

Design methodology

The design is conducted according to the Pugh’s total design methodology. The design procedure

follows two distinct steps: conducting a needs analysis based on socioeconomic factors of rural

households in India and consequently designing to meet those needs. The design is evaluated using

quantitative studies with a small element of qualitative. The quantitative consists of laboratory

experiments and the qualitative is the quality factor of the finished product. It assesses the aesthetic

properties of the final product and the quality of finish. A rough sketch of the product, followed by a

Computer Aided Designing (CAD) model of the product will deliver the final product, a Pelton wheel,

as a 3D printed replica.

Initial research – books, reports, online articles, journals

Literature review – reports, books and journals. Publish date range

2010 – 2015

Formulate design – based on information gathered from literature

review and socioeconomic factors

CAD modelling – based on the formulated design. Use CATIA software

to model 3D design and 3D print final design.

Discuss results and form conclusions

Give recommendations

Figure 1.1:

Methodology flowchart

Chapter two – Country profile

India

Consists of twenty nine states.

the world’s seventh largest country – total land size 3,060,500 km2

the second most populous country in the world after China – population of 1.2 billion

Average population density - 420 people per km2

(The World Bank, 2013)

East is densely populated with up to 12,000 people living in one km2

as shown in the

figure to the right

Figure 2.1: State-wise population

densities per 2011 census. (Source:

Wikimedia)

Socioeconomic factors

India has a booming economy

India has the world’s tenth largest economy (CNN money, 2014)

also ranked ninth by nominal Gross Domestic Product (GDP)

Third by Purchasing Power Parity (PPP).

India is also forecasted to have the world’s 4th

largest GDP growth in 2015

(Bloomberg)

Agriculture employs 53% of India’s workforce, yet it only contributes 14% to India’s

GDP (Planning commission, Government of India, 2014).

The services sector accounts for 57% of GDP in 2012, only employs 27% of the

workforce.

This suggests that the agricultural industry is the least profitable.

Figure 2.2 (left) and figure 2.3 (right): Sector wise employment, and sector contribution to GDP

(source: Wikimedia)

On the other hand

India is ranked 147th

by GDP per capita

125th

by PPP per capita (The World Bank 2013).

Monthly average wages in India are 803 PPP GBP which is among the lowest in the

world.

In agricultural regions workers can earn as little as 67p per day

More than 20% (269,783 people) of the Indian population live under the poverty line

in 2011-12. (Reserve Bank of India, 2013)

This suggests that the agricultural workers are the most likely to be under the poverty

line.

North East India

Consists of eight states: Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram,

Nagaland, and Tripura

Makes up approximately 8% (262 thousand km2) of India’s total land space

Accounts for 3.2% (40 million) of the Indian population

The largest state is Assam which covers 30% of the land and has 77% of the total

population.

Assam has a population density of 390 inhabitants per km2

Climate

Varies between humid subtropical and montane

Humid subtropical - Extremely wet monsoon seasons followed by exceedingly dry

winters.

Summer - 20 °C - 25°C

Figure 2.4: Statewise Average rainfall

in centimetres Source: maps of India,

2012

Winter - 0°C - 15°C

The monsoon season lasts from May to September

Supplies about 80% of the annual rain

Majority of North East India receives about 200 - 400cm of annual rainfall

In Southern Meghalaya average annual rainfall exceeds 800cm

Mawsynram is the current record holder for most rainfall in a year with annual rainfall

of 1187cm, followed by Cherrapunji with 1143cm. (Guinness World Records, 2015)

Table 1: Rainfall level in Mawsynram and Cherrapunji. Source:

Guinness world records

Despite heavy rainfall for most of the year, the Northeast is in increased risk of drought from

October to January when there is almost no rainfall. As North East India, particularly Assam

relies on agriculture alone for income; a weak or failed monsoon season can have a

devastating effect on the local economy.

Year Cherrapunji Rainfall

(mm)

Mawsynram Rainfall

(mm)

2010 13,472 13,300

2009 9,070 13,965

2008 11,415 14,985

In conclusion, there is a large potential in hydro-power to electrify rural villages in North

East India particularly owing to the strong monsoon season. The rainwater can also be

captured and filtered for drinking water during the dry season. In addition, solar energy may

also be exploited.

Economy

The economy of North East India is agrarian (dependent on agriculture) and remains the least

developed and most financially stunned. There are a number of factors which contribute to

this lack of financial growth:

1. The terrain which is largely inaccessible and difficult to cultivate crops on. This

means that little land is available for settled agriculture.

As it can be seen by figure x, the majority of the North East consists of scrub and forests with

Assam and parts of Tripura used for agricultural purposes. Figure x shows the GDP per capita

in each state. It is evident that Eastern Indian states have the least GDP per capita compared

to West India around Maharashtra which has the highest.

Fig. 2.5 (left) and 2.6 (right): Map depicting major commercial crop areas; and the statewise

GDP per capita. (Source: Maps of India)

The reason for low profit from farming is possibly due to the primitive farming methods such

as slash-and-burn which takes place in the hills and leads to soil degradation in the long term;

in addition to traditional single crop farming which takes place in the plains. The food grain

produced using these methods are hardly adequate to feed the local population; and as a result

there is few crops remaining for trade. Natives are left with little choice but to import food

from other states, using up what little GDP they have.

2. India’s ‘Look East’ policy was introduced in 1991 as part of a strategic and economic

bond between India and neighbouring far Eastern countries. Due to its rich natural

resources, the North East is seen as the pinnacle of the Look East movement: natural

resources including coal, oil, and uranium have been exploited by the Indian

government over the many years; while neglecting the economic state and flooding

the area with immigrants. This reason, fuelled by the isolation from the rest of India,

has caused much turmoil between the North East and the Indian Government.

3. Industrialisation in North East India has been a difficult task to achieve mainly due to

a weak economic foundation. Lack of market accessibility, an adequate road network,

and communications continue to hinder the economic progress of the North Eastern

states: it is not seen as feasible to establish an industry here because of these reasons.

Fig. 2.7: Statewise poverty levels

(source: Maps of India)

Living standards

Healthcare

The healthcare status in NER India has improved across the rural states thanks to the

implementation of the National Rural Health Mission (NRHM) since its launch in 2005. Prior

to its launch the NER was one of the regions with “weak public health indicators and/or weak

infrastructure” (Ministry of Health and Family Welfare, Gov. of India). This initiative

introduced many new healthcare centres across the North Eastern region. Tripura and

Nagaland in particular received more healthcare centres as can be seen from the table below:

Fig. 2.8: Progress of rural health centres in NER.

Source: Dilip Saikia, 2014

Conversely, the facilities and educated manpower employed in the health care centres is poor.

From the tables shown below it is clear that in terms of facilities Manipur suffers the most

while Mizoram enjoys the best facilities. In terms of electric supply, a massive 67.5% of sub

centres in Assam do not have an electric supply, followed by Meghalaya and Manipur with

65.4% and 63.8% respectively. Lack of sub centre electrification is also an issue in Nagaland

and Tripura. With respect to manpower, a general shortfall is apparent in Arunachal Pradesh,

while in Manipur the manpower is the strongest. However Manipur suffers from the least

amount of facilities and electricity hence the manpower cannot be fully utilised.

Fig 2.9: Facilities and Manpower status of healthcare in NER India.

Source: Dilip Saika, 2014

Education

Education is fundamental in order to expand as an economy. Many studies (Madigan, 1981;

Saunders et al, 1978; Herring, 1979) have shown that rural electrification, income and

education have a strong positive relationship. Education can contribute to better lifestyle,

higher wages, a better healthcare system and a solid economy. The Northeast suffers from a

flawed educational infrastructure, low teacher wages, absence of facilities and unmanageable

class sizes. In addition, many NER private and public schools are largely inaccessible for

many children as there is no established road network. In regions such as Assam people have

such meagre incomes that they simply cannot afford to send their children to school and

instead keep their children as extra hands on the farm. Figure x below (left) shows the

literacy rate per state in 2011. Clearly, the NER, particularly Assam, Meghalaya and

Arunachal Pradesh has a below average literacy level. Conversely, the government-run states

of Tripura and Mizoram have the highest literacy level.

Fig. 2.10 (left) and 2.11 (right): statewise literacy levels; and the impact of electricity over

time on literacy levels (Souce: Maps of India; Barnes et al, 1988)

Figure x above shows the correlation between number of years a village has been electrified

and its literacy levels. Evidently, the literacy levels grew as years passed with electricity

supply. This suggests that at the bare minimum, electrification is a catalyst for village

children to become literate and lead the way to build a stronger economy. (Barnes, 1988)

Wages

How strong a regional economy is affects the wages workers receive. A recent study by the

labour bureau of India (2013-14) showed that amongst agricultural roles, logging and wood

cutting was identified as top-paid position for men with an average daily wage of £3.31;

whereas for women the top-paid occupations were ploughing & tilling workers which earned

an average daily wage of £2.09. Child workers earned up to £1.70 for harvesting crops and

£1.50 for sowing. This equates to 40p an hour for a wood cutter, 26p for a ploughing worker,

and 21p an hour for a harvester (assuming 8 hours of business time).

In non-agricultural jobs, men who worked as a plumber, electrician or mason received the

highest daily pay. The plumbing occupation brought in £4.25 of daily income for men. For

women, the highest paid profession was masonry which gained £2.86 of daily living income.

Children who laboured as construction workers were likely to earn the highest pay of £1.57.

To place this into perspective, the ‘big mac index’ can be adopted. This measure the working

hours required to buy a big mac in different countries.

Fig. 2.12: Big Mac Index comparison by

country. Source: Lisa Mahapatra,

International business times, 2013

Summary

The key points from chapter two are as follows:

India has a strong overall economy, yet 20% of the population are below poverty line.

This indicates poor state-level economy hence poor wages.

Humid-subtropical climate of the Northeast means very heavy rainfall from April to

September which could be harnessed using hydro-power technology

The regional economy is agrarian

The economic growth of the Northeast region is staggered by a poor socio-economic

framework, undeveloped road networks, inadequate communication services and the

unavailability of agricultural land. Also a failed monsoon causes a shortage of

commercial crops.

The poor economy therefore has a direct impact on living standards such as

healthcare, education, and wages of the local population which are insufficient to

serve the population.

Outcome

Supplying the Northeast region with electricity will provide the region with new

opportunities to expand and grow as an economy. The Gross Domestic Product of the region

will increase, which has a direct positive impact on income. When household income

increases the population will be able to afford better healthcare and education for their

children. A radical action must be taken also to subsidise the cost of electrification to make it

affordable to all, including BPL households.

Chapter three – Rural electrification

Current state of rural electrification

Rural electrification is the process of supplying electricity to sparse remote areas. Compared

to urban populations, rural populations have lower annual earnings and work more hours, as

discussed above. Rural areas often have difficult and treacherous terrain which means

unfeasibility of employing an electrical grid. In addition, these regions suffer from an

undeveloped road network, absence of communication and isolation from the peer states

makes maintenance of electricity sources difficult to achieve.

Current definition of rural electrification from Government of India:

“The basic infrastructure (distribution transformer and/or distribution lines)

The number of households electrified should be at least 10% of the total households in

the village.”

Under this definition, NER have made significant progress on the electrification on the region

thanks to Rural Electrification Corporation Ltd. (REC) as the prime mover. As of 2015, there

are about 89% of NER villages electrified with a goal to achieve complete rural

electrification by 2025.

Table 2: Village electrification rate by North Eastern state as of January 2015

State Number of inhabited

villages as per 2011

census

Percentage of electrified

villages

No. of unelectrified

villages

Sikkim 425 100 0

Tripura 863 97 26

Assam 25372 96.8 803

Mizoram 704 91.1 63

Nagaland 1400 90.8 129

Manipur 2379 86.6 318

Meghalaya 6459 80.1 1284

Arunachal Pradesh 5258 70.3 1564

Source: Central Electricity Authority CEA, India, 2015

The data above shows good electricity coverage to villages in NER states. It is clear from the

statistics above that Sikkim is the most electrified state with 100% of the villages receiving

electricity; whereas fewer of the villages in the state of Arunachal Pradesh are electrified

(70%). In terms of households however, the above figures are considerably lower. According

to the 2011 census of India, less than 60% of households in the states of Assam, Tripura,

Manipur, Meghalaya and Arunachal Pradesh have electricity as a means of lighting; and in

Arunachal Pradesh a massive 14% of households have no access to lighting. The state of

Assam in particular has the lowest percentage of household electrification at 28.4%

(1524221), although table 2 implies that village electrification levels in this state are some of

the highest at 96.8%.

State Meghalaya Assam Sikkim Nagaland Tripura Arunachal

Pd.

Mizoram Manipur

No. of

houses

with

electric

lighting

217739 1524221 83277 214319 361573 108550 72138 205444

% 51.6 28.4 90.2 75.2 59.5 55.5 68.8 61.2

No. of

houses

with no

lighting

3768 10221 527 4231 2147 27321 500 2286

% 0.9 0.2 0.6 1.5 0.4 14 0.5 0.7

Table 3: Household lighting sources.

Source: CensusInfo India 2011

From this data it can be concluded that although a large number of NER villages have been

electrified, there is yet a large quantity of houses with no electrical powered lighting, or no

lighting of any kind. This is largely due to the arrangement of Indian villages which can be

dispersed making it difficult to build a common grid. Furthermore as discussed in chapter x,

education has a substantial effect on income: where the higher educated states can earn more

income and can therefore afford electrification and vice versa. This is mostly apparent in

Kerala which has mostly skilled workers who receive higher pay; whereas in Arunachal

Pradesh which has the lowest literacy rates in the NER, workers earn less income: leading to

a shortage of electricity. Other obstacles hindering the electrification of households in NE

India include poor planning, lack of political drive, poverty, and power theft.

Options

Village electrification programmes take the form of renewable energy sources such as solar,

small hydropower, and non-renewable resources such as coal and biofuel. The potential, uses,

advantages and challenges of these will be discussed below.

Renewables

Solar

The main principle of solar energy is: Photovoltaic (PV) cells extract energy from the sun

using photon particles contained in ultraviolet (UV) rays from the sun to excite the silicon

atoms within the cell. Excitation of silicon cells causes them to emit electrons which generate

electricity. In another variety of solar cell, the sun’s energy is used directly to heat water

flowing through coiled pipes via a heat exchanger surface.

India has a vast potential for solar energy: more than 300 sunny days guarantees an enormous

solar power potential. The potential for solar energy is lower in North East India due to its

cooler tropical humid climate, however in certain states which have clearer skies, such as

Assam the potential for solar is higher.

Solar potential is directly related to the temperature of the

region and the number of sunshine hours. Figure 3.1 to the

right (Ganesh, 2007) shows the average temperature for

each NER state. It can be seen that the majority of the

NER have annual temperature range of 22.5 - 25°C, while

some regions around Meghalaya, Sikkim and the state of

Arunachala Pradesh have cooler climate ranging from

below 20°C to 22°C.

The table given below shows the state-wise solar power potential in NER India.

State Solar power potential (GWp)

Assam 13.76

Manipur 10.63

Mizoram 9.09

Arunachal Pradesh 8.65

Nagaland 7.29

Meghalaya 5.86

Sikkim 4.94

Tripura 2.08

Rajasthan 142.31

Table 4: Statewise solar potential. Source: MNRE, 2015

As it can be seen by the data shown above the solar potential in Assam is greater than solar

potential in Manipur by a factor of 3% (13.76 GWp compared to 10.63 GWp). Yet Assam’s

great solar energy potential remains untapped, although the Indian power company North

Eastern Electric Power Company (NEEPCO) have plans to build a 5MW solar plant in Hojai-

Lanka, Assam (NEEPCO, 2014). For comparison, the state of Rajasthan with its arid climate

and scorching heat has 142.31 GW of solar potential. Conversely Sharma et al, 2011 argues

that more than 3600 remote villages in India, including those in NER have been successfully

electrified through solar. Therefore JNNSM initiative has been successful in designing and

implementing solar systems. Next steps would be to standardise systems so that they are

locally manufactured and to subsidise the cost to make it more affordable for poor houses.

Uses

Solar energy has a variety of uses that range from domestic lighting to district-level water

heating purposes. According to the data collected by The World Bank (2014) based on the

2011 census, that 2.9% of the houses in Arunachal Pradesh use solar powered lighting;

followed by Tripura and Manipur (1.9%). The data below shows the different uses for which

solar energy was employed for in March 1998. It is clear that Assam had employed solar

energy for every purpose, mostly for solar home systems and Solar Water Heating System

(SWHS). The rich state of Tripura could afford to build more solar home systems and power

plants, whereas poorer region of Nagaland could not afford to put solar energy to many uses.

Fig. 3.2: Statewise applications of solar energy devices.

Source: North Eastern Council Shillong

Advantages

Renewable energy – never runs out

Produces no pollution during operation

Requires little maintenance – no moving parts

Silent

Can feed excess energy generated back to grid for money – feed-in tariff

Disadvantages

High initial investment

Costly energy source – 25p/kWh (25+ Rupees). Few states can afford these prices.

Intermittent – Only works when there is sunlight

Needs to be facing the sun for best efficiency

Inefficient – 20% conversion efficiency

Wind

The potential for wind energy is limited in the Northeast, except for the minor red areas on

the map on the right which indicate a power density at 50m altitude of between 200-

250W/km2. This area is well covered from the strong winds by the Himalayas so little of the

wind actually escapes into the NER states. There is therefore no real investment in Wind

power in this region for this fact.

Fig 3.3: statewise wind power potential. Source: Infographics, 2010

Small hydro

Hydropower is a very attractive energy source in this region due to its high rainfall and

sloping hills which make great natural sites for micro (5-100kWe) and Pico (<5kWe) hydro

power. As it can be seen from the map below Arunachal Pradesh has over 831MW of

potential in small hydro, whereas Assam, Meghalaya and Sikkim have up to 300MW of

hydropower resources. This is supported by the table given below.

Fig. 3.4: statewise Small hydro potential. Source:

Thelearningpoint

Much of this potential remains unharnessed. According to the Central Electricity Authority of

India, Assam has harnessed almost 60% of its 680MW hydropower capacity; whereas

Tripura and Mizoram have captured none of their hydropower capacity. The state of

Meghalaya, despite its abundance of rainfall, has captured only 12% of its 2.4GW capacity.

Arunachal Pradesh has by far the best potential for hydropower (50GW), however due to

inaccessibility of the region and the resulting impracticality of projects; the majority of the

capacity is unused.

State Total Capacity (MW) Installed capacity

(MW)

Installed capacity

(%)

Meghalaya 2394 282 12.27

Tripura 15 0 0

Assam 680 375 57.69

Manipur 1784 105 5.96

Nagaland 1574 75 5.17

Arunachal Pradesh 50328 405 0.81

Mizoram 2196 0 0

Table 5: Statewise small hydro total and installed capacity

Source: Central Electricity Authority, Gov. of India (2015)

However Government of India has set goals for 2020 to encourage the utilization of this plentiful

resource. Application of SHP is especially economical at sites where there is no access to the grid, or

it is uneconomical to serve from the grid due to the dissemination of rural households.

Non-renewable

Thermal

The only thermal plant in the North East region exists in Tripura state called “Palatana Power

Plant”. It is capable of producing 726.3MW of electrical output which is then shared amongst

the neighbouring states. The plant is a combined cycle gas system which means it is twice as

efficient as a coal power plant, and uses half the fuel.

Advantages:

Reliable – can be in constant operation

Flexible – can meet different energy demands

Efficient – up to 65%

Large scale – Can feed electricity to many households

Disadvantages

Environmentally polluting – releases sulphur, CO, and CO2 into the atmosphere

Requires a non-renewable energy source

High capital cost

Power has to be transmitted via grid

Large use of land space

Impact of rural electrification

The impact of supplying electricity to Northeast India could be substantially positive. Routine

activities of a typical North eastern family could be made dramatically simpler by providing

electricity. Arduous tasks such as fetching water, buying kerosene fuel, collecting wood for

fuel, may be eliminated completely and cooking made considerably shorter: freeing up more

time for leisure and family time. An evaluative study on the impact of access to electricity in

India (Pereira et al, 2011) found that household electrification will affect women and children

more than men. Women will be left with more time to read books, watch TV and do their

hobbies; and children will be under less pressure to perform chores or help on the farm: hence

longer study time. Evidently from the table below women who had electricity expended

considerably less time gathering fuel (0.32 compared to 0.90 hours) and more time reading

(0.32 hours) and watching TV (1.63 hours). Moreover, the study found that women

performed less labour when they had electricity compared to women without energy access.

This could suggest agricultural improvements as women are typically occupied on the farm.

In addition to this the study found a strong positive correlation between an increased interest

in reading and electricity supply.

Fig. 3. 5: Comparison of allocation of time on activities for women with and without

electricity.

Source: Pereira et al, 2011

Benefits can also be seen in well-being factors such as healthcare and education. According

to Ahmad et al, 2014 the entitlement to electricity had a strong positive correlation to well-

being indicators. It found that fewer children were absent and more were enrolled in regions

or households with electricity than those without. Absenteeism in children from non-

electrified households occurred 0.3 days per month more often than it did with children from

electrified households. A possible explanation for this pattern could be that children from

electrified households are expected to perform fewer chores and can therefore spend

additional time studying. These children may consequently have increased confidence and

morale during class owing to the extra study time. Also, there was a reduced illness rate in

electrified households.

Furthermore agriculture may benefit immensely from electricity. Oda, 2011 concludes from

the survey of 80 villages in five districts in Bihar that energy access has direct impact on the

cost of irrigation and processing of crops and storage of said crops. It also found that

electrified villages had more irrigated land than ones without: showing that agricultural

activities are made simpler and performed at a faster pace. Moreover, Hirashima et al (2011)

suggested that energy access increased the probability that rural development programs were

implemented in a village; adding that electrified villages had more opportunity due to

simplification of developing the village.

Another key issue with rural electrification is that the electricity supply from national grid is

unreliable with a high outage rate which continues for prolonged hours. Although grid

connection increases non-agricultural household incomes by 9%, a higher quality electricity

source boosts household incomes more than threefold (29%) (Charavoty et al, 2014). Rao,

2013 proves that the quality of electricity supplies, in terms of hours a day and outage rate,

has a strong impact on household income. Rao conducted a survey on 42000 households and

found that 16 hours a day of electricity supply was optimum for increasing household

earnings. It is estimated that Indian GDP value could grow by 0.1% (equivalent to £650

million) if every household Non-farm enterprise (NFE) was provided with a stable electricity

supply. This survey is limited to NFE’s and does not consider the economic development if

all households were to be provided with the same electricity supply. Therefore to apply this to

all Indian households the gain in GDP will be considerably larger.

Summary

The key findings of chapter three are as follows:

Village electrification has been successful on a vast scale (up to 90%), whereas based

on household electrification the success rate is low (less than 60%).

Options for rural electrification were assessed. Small-hydro has the largest potential in

Northeast India (almost 60GW), although a large percentage remains unused.

The impact of realizing rural electrification in Northeast India was discussed. Women

and children benefit most from rural electrification, as well as the disposable

household income which could increase to 29% on the basis of stable electricity (16h

a day) and minimum shortages.

Outcome

From the knowledge found in this chapter, it is evident that small-hydro has the greatest

potential in supplying electricity to the Northeast region, as well as being the most cost

effective. For this reason, Pico hydropower will be discussed extensively in the following

chapter.

Chapter four – Hydro-power

Hydro power is the conversion of the potential, kinetic and pressure energy of falling water to

mechanical energy in the turbine and then to electrical energy in the generator. According to

the laws of physics, any physical body with a mass (m) that is higher than ground level

possesses a potential energy from the pull of gravity.

This basic principle is used in hydro-power when a body of water is stored (usually in a dam

or a forebay tank) above the ground with a static head (h), and then released towards the

ground under gravitational pull. This fluid travels in pipes with large diameter which become

small as they pass out through a nozzle and exert a force on the hydroelectric wheel which

spins a shaft fixed to a generator.

The fluid flowing in the pipes also possesses kinetic and pressure energy. The kinetic energy

arises from the velocity of the fluid and the gravitational pull of the Earth. The pressure

energy is caused by the flow of a volume of fluid through a small diameter pipe: The smaller

the pipe area, the greater the pressure energy.

The relationship between potential, kinetic and pressure energy is described by Bernoulli’s

theorem:

𝑬𝒏𝒆𝒓𝒈𝒚 𝑯𝒆𝒂𝒅 𝒑𝒆𝒓 𝒖𝒏𝒊𝒕 𝒘𝒆𝒊𝒈𝒉𝒕 (𝑯) = 𝒉 +𝑷

𝜸+

𝑽𝟐

𝟐𝒈 - (1)

Where:

h = static head (m)

P = Pressure

𝛾= Specific weight of the water (𝛾 = 𝑔. ℎ)

V = Velocity of the water (m/s)

g = Gravity (m/s2)

The power in Watts (P) generated from the turbine is given by:

𝑷 = ƞ𝝆𝑸𝒈𝒉 - (2)

Where:

Ƞ = Efficiency of the turbine (%)

𝜌 = Density in kg/m3

𝑄= Volumetric flow rate in m3/s

𝑊ℎ𝑒𝑟𝑒 𝑄 = 𝐽𝑒𝑡 𝑎𝑟𝑒𝑎 × 𝑗𝑒𝑡 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦

Why Pico hydro?

Pico hydro represents any form of hydro power station that is capable of producing up to five kilo

Watts of electrical output. It is the smallest form of hydro available. Typically five kilo watts are

sufficient to power an entire village depending on the population and the electrical demand of that

village.

Most household in NER have basic electrical needs such as TV, radio and lighting. Their heat

source for cooking comes from burning wood, and for cleaning they use nearby sources of

water. During the day cooling may be necessary so a fan could be installed. Also, mobile

phones have recently become prevalent in villages therefore a source to charge them has to

follow.

Overall, a typical Indian village household consumes up to 300W of electrical energy. A

typical Pico hydro runner can generate 300W of electrical energy with ease. It only requires

a stable source of water, and a sufficient drop in height.

Benefits:

Little to no planning

Up to 75% efficiency

Little use of land

Environmentally-friendly technology

Low sound and visual pollution

Low cost per kWh

Low maintenance – Can be maintained by the local community

Principles of Pico hydro-power

In essence, Pico hydro is a smaller version of large scale hydro without the need for

damming: this significantly reduces costs and environmental damage. Pico hydro uses fewer

components and shrinks the size of a hydro system so that it is versatile and can be used

anywhere as long as there is a constant flow of water and an adequate drop in height.

Power generated (W)

The power delivered by the system in Watts is derived using:

𝑷 = ƞ𝝆𝑸𝒈𝒉 - (2)

Frictional head loss (hf)

Head loss can be described as the loss of available height drop through friction in the pipe.

The greater the head loss, the less the energy passed on to the turbine. This is used to

calculate the net head: the available head after losses have been accounted for.

𝒉𝒇 = 𝒇 × [𝑳

𝑫] ×

𝑽𝟐

𝟐𝒈 -(4)

Where:

L= Length of pipe; D= Diameter of pipe; V= Velocity of fluid; g= Gravity (9.81m/s2)

F = friction factor which can be directly computed using

𝟔𝟒×𝒗

𝑽×𝑫=

𝟔𝟒

𝑹𝒆 Where Re is the Reynold’s number and 𝑣 is the kinematic viscosity -(5)

𝑹𝒆 =𝑫×𝑽

𝒗

𝒗 =𝝁

𝝆

Substituting friction factor into (4) gives:

ℎ𝑓 =64×𝑣

𝑉×𝐷×

𝐿

𝐷×

𝑉2

2𝑔=

32×𝑣×𝐿×𝑉

𝑔×𝐷2 -(6)

Torque applied to the turbine

𝑇 = 𝜌𝑄𝑉𝑗2𝑟 -(7)

Where r = runner radius and Vj = Jet velocity

Power developed from the turbine

𝑃 = 𝑇𝜔 𝑜𝑟 𝜌𝑄𝑉𝑗2𝑟𝜔 -(8)

Where 𝜔 = Angular velocity of the wheel

Efficiency (ƞ)

ƞ =𝑂𝑢𝑡𝑝𝑢𝑡 𝑠ℎ𝑎𝑓𝑡 𝑝𝑜𝑤𝑒𝑟

𝐼𝑛𝑝𝑢𝑡 𝑝𝑜𝑤𝑒𝑟=

𝑇𝜔

𝛾𝑄ℎ -(9)

Fluid dynamics

Kinematics

Ideal fluid

In such a fluid it is assumed that there is no viscosity: particles are flowing adjacent and with

uniform velocity. This is hypothetical and does not exist, however there are cases where

assuming ideal fluid flow may help.

Real fluid flow

In a real fluid viscosity is introduced into the problem. A real fluid displays characteristics of

shear stress caused by viscous forces between neighbouring particles. In the case of real fluid

flow in a pipe, the velocity at the pipe wall will be zero: this will increase dramatically as it

nears the centre of the pipe and induces a velocity gradient as shown below.

Fig 4.1: Ideal and viscous fluid velocity profile

Source: www.anbg.gov.au, 2013

Incompressible/compressible

An incompressible fluid is assumed to have constant density. Although liquids display minor

fluctuations in density, most fluids can be described as wholly incompressible. Gases may be

classified as compressible as their density changes with absolute temperature and absolute

pressure.

Gravity or pressure flow

When a fluid flows through a partly full pipe under the force of gravity it is called gravity

flow because gravity is the prime moving force. However if it moves in a full flowing pipe

then pressure flow is introduced into the equation as the flow is under pressure.

Laminar flow

When a fine coloured liquid is injected into a stream of water travelling at a slow velocity, the

particles can be observed to travel as parallel straight lines and there will be no mixing of the

particles. The particles can be said to be sliding in thin layers adjacent to each other so that

there is a definite and observable path. This is also known as viscous flow as it is

characteristic of a viscous fluid.

Turbulent flow

As the velocity of the stream is increased, at a certain velocity the water and injected fluid

begin to mix so that there is no definite path. An irregular motion can be observed as large

swirls. On a microscopic level packets of particles called “eddies” form all with fluctuating

velocities and they collide in a random manner. Every particle follows a random path and no

two particles follow the same pattern. This is the reason for the mixing action.

Fig. 4.2: Laminar and turbulent flow behaviour.

Source: edu-cdn.com, 2012

Dynamics

Reynold’s number (Re) - (10)

The Reynold’s number is the ratio of inertia force to viscous force of a fluid. In fluid flow the

inertia force is the force opposing the flow of water caused by friction between the pipe

walls. Viscous force is the measure of shear stress τ caused by the velocity gradient in a

fluid travelling in a pipe. As discussed above viscous force is apparent in all real fluid flows.

The Reynold’s number with respect to velocity (V), pipe diameter (D), and kinematic

viscosity (𝒗) can be determined using:

𝑹𝒆 =𝑫×𝑽

𝒗 - (11)

The Reynold’s number is an indicator of whether the flow is laminar or turbulent: laminar

flow occurs at low Reynold’s numbers, while a high Reynold number is characteristic of a

turbulent flow (Re >2000).

Viscosity

Viscosity is a fluid’s resistance to shear stress. The viscous force is caused by cohesion of the

fluid particles against the friction between the pipe walls.

In fluids, viscosity decreases by raising the temperature. Below is a diagram that depicts how

viscous liquids react to increasing temperature.

Effect of viscosity on fluid flow

Consider a space containing water sandwiched between two sheets: one stationary plate and

one moving plate with a velocity V. At the top boundary (u=V, y=h) there is a velocity V

which gradually decreases as it nears the bottom (stationary) boundary at which point V= 0 at

y = 0: where y refers to the distance from the datum boundary and u refers to the velocity at a

point along the y axis. This forms a velocity profile. Velocity relative to the boundaries is

zero as the particles adhere to the walls as is the case for all viscous fluids: this is called the

no-slip condition.

Fig. 4.3: Velocity

profile through shear

between two plates

Since the shearing stress between the two plates 𝝉 = 𝝁𝒅𝒖

𝒅𝒚 - (12)

The dynamic viscosity or simply viscosity 𝝁 = 𝝉/(𝒅𝒖/𝒅𝒚) - (13)

The kinematic viscosity does not involve force and is computed using

𝒗 =𝝁

𝝆 - (14)

The viscosity (dynamic) of water = 1.002 kgm-1

s-1

(Pa s) at 20°C.

Density, specific weight and gravity

Density ρ of a fluid is the mass per unit volume or kg/m3. Specific weight 𝛾 is the weight per

unit volume of the fluid (N/m3). This unit is not absolute and is dependent on the gravity

which changes with location and mean height above sea level. For this report gravity is

assumed as 9.81m/s2.

The relationship between these three values gives:

𝝆 =𝜸

𝒈 - (15)

Where specific weight 𝛾 of water at 20°C = 9790 N/m3

or 9.79 kN/m3

Kinetic energy

A body of mass m that is in motion with a velocity V has a KE of 1/2 𝑚𝑉^2 . For unit

weight of the fluid this can be expressed as: 𝑉2/2𝑔. For unit mass: 𝑉2/2 ; and for unit

volume: 𝜌𝑉2/2 .

Potential energy

The energy contained in the weight of an x amount of fluid depends on the height above a

datum plane (h). This can be taken as ground level. Therefore the potential energy in a gallon

(4.5kg) of water at height difference h from ground level is computed as:

PE = mgh = 4.5 x 9.81 x h

Jet velocity and pressure

Upon reaching a jet orifice a stream converges and continues to do so until it reaches a point

called vena contracta. This is known as the minimum area of the streamline. This area is

commonly 0.5Do where Do is the diameter of the orifice. Beyond this section the stream

proceeds to deviate due to frictional effects. An orifice with a rounded entry has no vena

contracta as it allows the streamline to converge gradually to the cross section of the orifice.

Fig 4.4: Vena contracta of an orifice

Source: diracdelta, 2010

Coefficient of contraction Cc

This is the ratio between the area A of the Jet and the area of the orifice Ao and is calculated

by using:

A = Cc Ao - (16)

It can be determined by measuring the jet diameter at the vena contracta by using calipers and

comparing the area of orifice by the jet area.

Coefficient of velocity Cv

This is used to describe the ratio between ideal velocity of the jet Vi and the actual average

velocity V. The ideal velocity is a figure assumed if there was no friction in the jet: however

this is not the case.

V = CvVi - (17)

Coefficient of discharge Cd

The ratio between the ideal discharge Qi of the water and the actual discharge Q is known

as coefficient of discharge Cd.

Q = CdQi - (18)

If Q = AV, then Qi = AoVi where: Q = rate of discharge, A = Area of Jet and V = actual

velocity

Therefore coefficient of discharge is a product of coeff. Of contraction and coeff of velocity

and it can be determined using:

Cd = CcCv - (19)

The pressure imposed on the impulse wheel casing is atmospheric therefore jet pressure will

also be atmospheric. Hence it will be assumed the jet pressure is discharged at 1atm or 1×105

N/m2.

The power of the jet emerging from the needle nozzle can be determined by:

𝑷𝒋𝒆𝒕 = 𝜸𝑸𝑽𝒋

𝟐

𝟐𝒈 - (20)

Basic components

A typical Pico hydro scheme comprises of the following components:

Forebay tank

Penstock

Valves

Water jets

Powerhouse - This encases the turbine and the generator

Load controller

The forebay tank is the main storage area for the water. It is placed at a height h above the

datum plane which is usually taken as the centreline of the water nozzle.

The penstock is a special type of reinforced pipe which is designed to minimize the effects

of water hammer. Water hammer is the build-up of pressure and stress in the pipe due to

blockage in the pipe or a sudden valve closing. It is required to direct the water downstream

from the forebay tank to the hydroelectric wheel. To minimize head losses in the penstock

they are usually large in diameter and made of a material with high internal wall smoothness

such as PVC or HDPE.

Valves are used to control the flow of water in a particular direction and/or control the

amount of flow rate. They are useful during maintenance or to meet fluctuating energy

demands, but can also have disastrous water hammer effect when closed suddenly.

The water jet, otherwise known as the needle nozzle varies the water flow to match the

required speed of rotation. The electrical load applied to the system is directly proportional to

the speed of gyration of the wheel. It is vital to maintain a steady rotational speed and this is

done by varying the position of the needle in the needle nozzle. As the opening of the nozzle

is expanded, the discharge of the water jet is increased; however the jet velocity is decreased.

Turbine is the general term for a turbine runner, the needle nozzle, and the casing. There are

two types of turbine runners: impulse and reaction. An impulse runner revolves as a free jet

of water impact on the buckets around its circumference. As the jet strikes the centre of the

bucket, it is split into two by the ridge in the centre of the bucket and is then diverted away

from the upcoming bucket so that momentum is not lost. Below is a diagram explaining the

action of the Pelton buckets.

Fig 4.5: Action of Pelton wheel and needle nozzle

Source: Fastonline, 2012

In a reaction runner the intake flow takes place in a closed chamber under pressure. There are

two general types of reaction runners: Francis, Kaplan and Axial type. There are many ways

that the flow through the turbine takes place such as radially inward, axial and mixed. In

summary, these runners are suitable for low-head applications (less than 15 metres) however

they are less efficient and also more expensive than a Pelton wheel.

The generator is connected on the end shaft horizontally between two bearings while the

runner is fixed to the protruding end. This configuration is known as the single overhung. A

double overhung system has two runners connected to the same generator. This is to balance

the bearing loads on both sides.

In a horizontal arrangement other machinery may be operated from the torque of the runner

using simple v notch belts and gearing. The efficiency in this case is lower due to friction in

the moving parts. In a vertical arrangement, the generator is below the turbine runner and the

complexity of bearing and shaft design is greatly reduced.

An electronic load controller (ELC) is vital in a hydro system to regulate the voltage to the

load applied to the system. Failure to incorporate a load controller can lead to malfunction

and damage to the electrical appliances drawing the current from the hydro system.

Fig. 4.6: Diagram showing how Pico hydro works

(Source: Practical Action, 2010)

Types of Pico-hydro schemes

In general there are three types of Pico hydro power schemes:

Run-of-river

Powerhouse situated at the bottom of a dam

Incorporated into a canal or into a water supply line

Run-of-river schemes

In a run of river system water from a flowing river is diverted by weir to the intake and

transported to the turbine via a penstock. Penstock pipe is expensive so for a high head run of

the river system low slope canals are used and then a short penstock to carry the water down

[ESHA, 2004].

Source: Worldwatch.com

Powerhouse situated at the bottom of a dam

Large dams that have been built for other intended purposes such as flood control, land

irrigation, recreation may be used as a potential site for a Pico-hydro plant. In this plant a

portion of the water flow is taken by the intake and transported below the dam by penstock to

the powerhouse. The water intake is usually an outlet at the bottom of the dam that can be

converted to an intake for a pico-hydro power plant.

Source: ESHA, 2004

Incorporated into a canal or water supply line

A Pico hydro station may be fitted into an enlarged canal which accommodates the turbine,

the drive shaft and a submerged powerhouse. Often in these schemes a Kaplan turbine is

used. A bypass parallel to the irrigation canal is also designed to ensure water supply for

irrigation while the turbine is in operation.

Source: ESHA, 2004

Drinking water supply usually comes from high head source such as a water tower or a

reservoir. A pipe carries this water down to supply the town with water. Fitting a turbine into

the supply pipe is an attractive option for generating electricity, so long as the water hammer

phenomenon is prevented.

Source: ESHA, 2004

Summary

The key points from chapter four are as follows:

The fundamentals of pico-hydro power were introduced and the subject of fluid

dynamics was described in detail. The basic components of a pico-hydro plant were

specified and their functions in the plant were defined. Finally the types of pico-hydro

schemes were identified and a description of each given.

Pipe inner wall surface smoothness and pipe diameter affects head loss therefore

choosing a larger diameter pipe with a lower pipe surface roughness coefficient

prevents energy being dissipated through friction.

Choosing a suitable turbine-generator set is dependent on the site conditions and the

measured head, and flow rate. A Pelton runner performs acceptably under all

conditions, although it is most efficient in high head, low flow applications.

Outcome

Using the background knowledge on Pico-hydro power plants obtained in this chapter

combined with the understanding of socioeconomic and geographical information of the NER

in chapter two; a design idea will be proposed to meet the requirements of the NER rural

population for electricity supply and drinking water, by harnessing the power of rainfall.

Chapter five – Design

Prior starting to design the following factors must first be considered:

The suitable sites – and head and flow rate of said sites

The turbine type

The penstock material

The local technical and manufacture capability

Start-up, operation and maintenance costs

Reliability

Standardization

The design is based on the highest annual rainfall figures in the North East India of

11,800mm. Assumptions are made that the rain is continuous and lasts the entire monsoon

season (April to September), and from October to January there is no rain.

Design requirements

Capacity of minimum 200W, medium head, low flow rate

Reliable - able to produce electricity for most of the year

Easy maintenance and running

Minimum start-up cost

Locally manufacturable

Standardised

Efficient

Affordable

Decentralized/off grid solution

Turbine selection

Williamson et al, 2012 proposed a method of turbine selection by defining the quantitative

and qualitative conditions, subsequently using Pugh’s matrix method to rate Pico runner

design to select the most suitable one. Below is a flowchart depicting the Williamson method

for turbine selection.

Source: Williamson et al, 2012

Source: Cobb et al, 2011 (adapted from Paish, 2002)

As it can be seen by the above table impulse turbine for a medium head applications consist of

Crossflow, Turgo, and Pelton runner. Therefore this restricts the selection to three possible turbine

runners.

Source: Elbatran et al, 2014

The table above shows all the possible selection criteria that can be used in the study. For

simplification, in this project the cost and efficiency quantitative criteria will be considered, and the

reliability, ease of manufacture and the maintainability qualitative conditions will be sought.

Source: Williamson et al, 2012

From the graph above it is evident that the single jet Pelton wheel was most efficient (up to

85%) at a range of head.

Source: Elbatran et al, 2014 (original source: Fraenkel et al, 1999)

It can also be seen from the efficiency – part flow curve that Pelton is again the most efficient

with efficiencies ranging from 0% at 15% flow to 85% at 60% flow. It is clear that Pelton

wheel is the most efficient runner, and Elbatran et al, 2014 recommends Pelton turbines due

to numerous other advantages including:

predictable performance under different conditions

ease of manufacture and maintenance

resistant to water contaminants such as sand particles which have low impact on the

runner performance

simple geometry

cost effectiveness

This information is adequate to conclude that a Pelton runner is most suitable to use in the

design. Moreover from the chart below it can be seen that at a 10m head, the optimum runner

size is 120mm pitch centre diameter (PCD) and best efficiency turbine speed is 1000 rpm.

Source: Maher et al, 2002

Design Idea

Below is a schematic of the dual rainfall harvesting and Pico hydro power generating design

idea. This device captures the unharnessed power of rainfall and converts it into electricity. It

features five needle nozzles to maximize the rotational velocity of the runner. The runner is a

Pelton type with a pitch centre diameter (PCD) of 120mm. The pitch centre diameter is the

diameter to the centre of the buckets which is tangential to the jet emerging from the nozzles.

The runner shaft can be coupled to a DC car/truck alternator or a 2/4/6 pole 3-phase

induction motor which are both largely manufactured in India and are inexpensive and

robust. The tailwater from the turbine is then stored in a tank which has two outlets: one

outlet is connected to houses and delivers filtrated water; while the other outlet allows water

to be pumped manually upwards to be recycled into the system.

Graph above shows that at a 10m head and 10m3

volume of storage tank it is possible to

extract up to 28 hours of electricity from the system when applying a load of 10W, equivalent

to two five watt ultra-bright LED spotlights producing sufficient light to illuminate a room.

Furthermore the capacity for 20W electrical load is high with a 14 hour lifetime. Typical

appliances and their electrical loads are given below. (Source: McKay, 2008)

02468

1012141618202224262830

0 1 2 3 4 5 6 7 8 9 10 11

No

. of

ho

urs

Volume of tank m3

Time - volume graph with 10 m head

10W

20W

30W

50W

100W

200W

Advantages:

Inexpensive and cost effective

Produces no environmental pollution

Provides houses with electricity and clean drinking water (which can be scarce in the dry

season)

Can be used as a secondary power source

Can be used during a blackout

Water storage tank can be used as an energy store: removing need for batteries

Allows the user to generate electricity to suit their demands

Can be delivered flat pack and constructed on site

Drawbacks:

Produces enough electricity to electrify one house

Intermittent – Depends on the precipitation level

May be visually polluting due to height of the structure

the motor may emit sound pollution

Cost considerations

In any hydro-power scheme it is vital to consider the costs in order to make it affordable to

the rural population. Here are some ways to reduce costs and increase the viability and

feasibility of pico-hydro schemes.

Low cost Penstock

HDPE or wood penstock is a suitable replacement for mild steel for head less than 75m.

Wood has been used successfully in Germany with a lifetime of 50-100 years. Since it is

abundant in India and inexpensive, wooden penstock may be used (Kusakana, 2013)

Locally manufacture turbine

Since the turbine is the main powerhouse of the system, it is also the most expensive

component. The cost can be reduced by locally manufacturing the turbine which also helps to

create jobs (Elbatran, 2014). The high success rate of locally manufactured parts particularly

in Nepal supports the viability of the process. Furthermore principles of sand casting can be

adapted to the manufacturing process so that Pelton runners can be single cast: reducing costs

further (Ho-Yan, 2012).

Standardisation of components

Cost of components represents a significant portion of the cost of any Pico-hydro system.

Standardizing the Pelton wheel geometry and manufacturing process will be particularly

beneficial in NER as the manufacturing technology and capability is limited in this region.

Furthermore, innovating the design of expensive components by combining them into a

single unit could lower civil, installation and transport costs. Turbine-generator sets such as

low cost DC power pc-hydro pack; the Peltric set; the Pico power pack have been developed

and manufactured in bulk in Colombia and Nepal with huge success (Maher, 2002; Lahimer

et al, 2012).

Community involvement

Community can get involved with all processes of the implementation of the design to reduce

cost and create jobs. Furthermore, energy suppliers may give bonus subsidisations to village

population who contributed to the employment of the pico-hydro plant (Elbatran, 2014)

CAD modelling and 3D printing

Below figures show the CAD model produced on CATIA, converted into stl file and imported into the

3D printing machine ready for preliminary error check and commencing printing. Figure 3 shows the

complete 3D printed runner and shaft. Figure 4 shows the dynamo circuit board which testing would

be conducted on.

(1)

(2)

(3)

(4)

Testing methodology

The testing element will not be conducted as planned due to timing restrictions however if they were

to be conducted the tests would determine the effects of:-

varying head (1m, 2m, 3m)

varying pipe diameter (10mm, 20mm, 30mm)

On:

Discharge (m3/s)

Power out (P)

Torque (T)

Efficiency (ƞ)

Voltage (V)

Amperes (A)

The testing will be conducted on a standard gallon (4.5kg) of water. The testing will determine the

values needed to calculate:

Jet velocity (Vj)

Kinetic energy (KE)

Potential energy (PE)

Energy Head (H)

Head loss (hf)

The experimentation would be supervised by a senior member of staff and all health and safety

regulations abided. Health and safety concerns include: drop of bucket onto personnel head and the

risk of falling from height.

The simple schematic below shows the experimental set up as it was planned.

Summary

The key points in chapter five are as follows:

Turbine selection criteria were defined and utilizing Williamson method a Pelton turbine with

a PCD of 120mm was selected as most suitable

Design idea was introduced and pros/cons of the device were reviewed

Cost reducing techniques were outlined for affordability of the scheme in rural India

CAD modelling and 3D printed Pelton runner was shown and the testing arrangement was

depicted.

Bu

cket

Var

yin

g H

ead

Dynamo

Nozzle

Pelton runner

Chapter six – Discussion

Discussion

In this report a Pico-hydro Pelton wheel design was developed by: (1) studying the socio-economic

background of Northeast India such as climate, economy, and the living standards; (2) research of

sources of electrification and their individual capabilities in the Northeast Region (NER); and (3) the

foundations of Pico-hydro systems including the typical components and schemes.

Initial socio-economic research was gathered using India census 2011 data which was analysed to

observe trends and pitfalls. The data suggested poor economy (GDP under £400 per capita) due to low

profits from commercial crops, and a weak communication and transport infrastructure. Furthermore,

the information hinted that electricity shortage negatively impacted welfare factors, especially wages

by as much as 29%. This suggested a large market for rural electrification henceforth an assessment of

the capabilities of different renewable and non-renewable energy sources were conducted using

figures from official Indian Government sources.

This assessment found no real potential for wind power or solar energy in NER, conversely small

hydro-power was found as the most viable particularly in the Arunachal Pradesh with a capacity of

80GW. Inaccessibility of the region due to harsh terrain limits this value to an estimated 15GW of

usable hydro-power: which is nevertheless a substantial amount awaiting to be harnessed.

The large potential of hydro-power led to research in the field and found that pico-hydro to be most

cost effective in rural regions: since Northeast is mainly rural it was decided that pico-hydro would be

the ideal source of electrification. Hence principles, scheme components, and scheme types of Pico

hydro were studied. Consequently the design was formulated around these three study areas and

design requirement was defined. The Pelton wheel was modelled using CATIA software and printed

using 3D printing machine. The finished product is shown in chapter five.

Chapter seven – Conclusions and recommendations

Conclusion

It can be concluded that electricity is a vital commodity that has a strong positive impact on

people’s lives. Electricity supply is a catalyst to growth and development and contributor to

quality of welfare development. It is income generating and will improve GDP growth and

household incomes of a region after implementation. Observing the data and figures gathered

in the report a meaningful conclusion would be although Pico hydropower is site-dependent,

it is the future for rural electrification, particularly in India. Pico-hydro has many suitable

sites in India, as well as globally and could one day be used to power all tropical rural regions

of the world.

Experimental results were not obtained however this report is a useful tool for anyone who

wishes to familiarise themselves with pico-hydro and its foundations. Also it is a good

starting guide for anyone who wishes to implement their own pico-hydro station or carry out

further research into pico-hydro in Northeast India.

Recommendations

One of the issues associated with rural electrification found in the report is the unfeasibility

of extending grid into remote rural areas. This issue can be resolved by using renewable

energy, namely solar and small hydro-power to decentralize remote areas. Hence villages can

be independent of the central grid and create their own electricity.

The regional population may also be unwilling to pay for electricity due to poor wages (as

discussed in chapter three) therefore subsidies to reduce the charge of schemes and cost

reducing techniques can be employed. Government grants can also be paid out to financially

aid the citizens for paying the electricity bills.

Further Research and Development is vital to standardise components, which simplifies and

reduces the cost of the manufacturing process. Thus components can be locally manufactured

instead of imported.

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