ENERGY EFFICIENT CITY: BANGLADESH PERSPECTIVE

Prepared by

M. Rezwan Khan Muhammad Qazi

Department of Electrical and Electronic Engineering UNITED INTERNATIONAL UNIVERSITY

DHAKA, BANGLADESH

May, 2005

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IMPORTANCE OF ENERGY EFFICIENCY

In the present day world, energy, particularly electrical energy, is the key driving force of civilization. Energy consumption throughout the world is increasing at an alarming rate. In this context, proper and efficient utilization of energy is of utmost importance considering the impact of energy usage on the environment and global warming. Every effort should be given to enhance the energy efficiency both from generation and consumption point of view to avoid an ultimate disastrous consequence. Therefore a systematic study of energy efficiency and power losses is required.

OVER VIEW OF ENERGY RESOURCES

With the growth in population and economic developments of different regions of the world, energy consumption is growing fast. The following graph in Figure1 shows the increase in the energy consumption of the world. World energy consumption is projected to rise by 59 % between 1999 and 2020, reaching 607 quadrillion British thermal units (BTUs). (1 quadrillion = 1015).

Figure 1: Trends in world energy consumption (source: US Department of Energy)

Dividing the energy consumptions into various regions in the world, we observe that developing Asia will be the largest contributor to the total energy growth and the high growth rate is expected over next two decades. Although the energy consumption in Bangladesh is still very low and only 30-35% of the population has access to electricity, percentage growth in energy consumption is quite high. The growth rate is expected to be even higher as private investors are stepping in. Hence, it is prime time for Bangladesh to formulate an appropriate energy policy, with proper emphasis on energy efficiency.

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Figure 2: World energy consumption by fuel type (source: US Department of Energy)

SOURCES OF ENERGY

To meet the growing need of energy in the world the sources of energy should be identified and discovered. Finding efficient sources of renewable alternative energy resource is necessary. The energy sources are divided into two groups:

Non-renewable (an energy source that we are using up and cannot recreate in a short period of time)

Renewable (an energy source that we can use over and over

again)

NON – RENEWABLE ENERGY: Speaking globally, we get most of our energy from nonrenewable energy sources, which are predominantly fossil fuels-oil, natural gas, and coal. Oil and natural gas are mainly hydrocarbons producing carbon dioxide and water vapour on burning. On the other hand, coal is predominantly composed of pure carbon and produces huge amount of carbon dioxide on burning. Most of the developed world prefers oil or natural gas as fossil fuel as they produce less pollution on burning. Bulk of our electricity in Bangladesh comes from natural gas. Recently, coal is discovered in the northern parts of the country (such as Barapukuria Coal Mine), which should be a boon for the power deficit region of north Bengal. However, curses of coal burning like discharge of carbon ashes in the air, land fall in the mine region and frequent mine accidents due to poor safety and maintenance should be seriously taken into consideration. For these reasons, coal is always considered as more environment unfriendly compared to natural gas or oil. Let us summarize the most consumed energy sources in the whole world: Oil: Oil is expected to remain the dominant energy fuel as it has been for decades. In the industrialized world, increases in oil use are projected primarily in the transportation sector, where there are currently no available fuels to compete with oil products. Natural gas: Natural gas is projected to be the fastest growing primary energy source worldwide, maintaining growth of 3.2 percent annually over the 1999-2020 period, more than twice as high as the rate for coal. Natural gas consumption is projected to rise from 84 trillion cubic feet in 1999 to 162 trillion cubic feet in 2020, primarily for electricity generation. Gas is increasingly seen as the desired alternative for electric

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power, given the efficiency of combined-cycle gas turbines relative to coal- or oil-fired generation, and because it burns more cleanly than either coal or oil, making it a more attractive choice for countries interested in reducing greenhouse gas emissions. Coal: Coal use worldwide is projected to increase by 1.7 billion short tons (36 percent) between 1999 and 2020. Substantial declines in coal use are projected for Western Europe and the EE/FSU countries where natural gas is increasingly being used to replace coal, to fuel new growth in electric power generation, and for other industrial and building sector uses . In the developing world, however, even larger increases in coal use are expected. The largest increases are projected for China and India, where coal supplies are plentiful. Together these two countries account for more than 90 percent of the projected rise in coal use in the developing world. Nuclear Energy: The other most challenging sector of energy generation is nuclear energy and it is considered to be one of the cheapest form of energy for future energy generation. Problems of nuclear waste dumping and possible health hazards from nuclear power stations make it a topic of great controversy and a break through like nuclear fusion is needed in the nuclear technology to make it more acceptable to environment conscious people. Present day picture of world politics sheds considerable doubt on world wide growth in nuclear technology which may be counter productive for the overall energy scenario of the world. It is highly unlikely that a country like Bangladesh will produce nuclear energy in near future. RENEWABLE ENERGY:

Renewable energy sources include

i) Solar energy, which comes from the sun and can be turned into electricity and heat.

ii) Wind iii) Geothermal energy from inside the earth iv) Biomass v) Hydropower

Besides hydro and wind, other renewable energy sources are still lagging behind in producing cheap energy at competitive cost. So far Bangladesh is concerned, we have very limited hydro potential. Other renewable sources like solar PV (photo voltaic) and wind are not yet cheap enough to compete with the grid power. This is solely due to the reason that solar insolation and wind speed are not high enough to generate low cost energy from these sources. However, for localized applications biomass and biogas may have a better future as poultry and dairy farms are becoming popular in rural areas.

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Figure 3: Energy Consumption by Sector, 2003 [1]

BANGLADESH PERSPECTIVE Though Bangladesh is overburdened with a huge population of around 140 million, only a small portion (30-35%) of the whole population have access to electricity. This energy consumption is mostly centralized in the cities. Due to inappropriate planning, existence of age old equipments, lack of organized research on energy consumption, a significant amount of energy is over consumed. As a large portion of the rural people is still deprived of the necessary supply, it is incumbent for us to find out alternative solution to provide them with the required energy. In our present energy setup, there are areas (sectors) where energy consumption can be lessened, meeting the present demand. A meager save in the energy consumption of the cities can prove to be quite significant extra supply for the rural areas. Such small energy savings in the city cumulatively will become a large saving for the whole country and consequently will enhance the efficiency level. ENERGY CONSUMPTION: Focusing on the sector wise Energy consumption we find that it is predominantly based on the domestic and industrial usages (41% and 44% respectively). Though there are other areas such as commercial and agricultural, it is obvious that domestic and industrial consumption occupy the major portion.

Total energy consumption in the cities are a mixture of domestic, commercial and industrial with very little or no contribution from the agricultural sector. Hence, improving energy efficiency in the cities effectively means better performance from all the consumer sectors. ENERGY CONSUMPTION IN THE CITIES The primary energy sources are as follows: Electricity: With the increase in industrial development and the growth of high rise buildings, electricity has become the primary source of energy in the city. Predominantly, electricity is used for lighting, heating, cooling, running numerous electrical appliances, operating large motors and motor drives.

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Table 1: The present gas reserve in Bangladesh (source: web portal of Renewable Energy Information

Network, LGED)

Figure 5: The total installed capacity of different types of power plants in Bangladesh (source: web portal of Renewable Energy Information Network, LGED)

Natural Gas: Natural Gas is a non renewable hydrocarbon resource and Bangladesh has substantial high quality natural gas reserve at the eastern part of the country. In the city areas, natural gas is mainly used for cooking and heating. Very recently, usage of CNG (Compressed Natural Gas) as an alternative fuel for the vehicles has been gaining popularity.

Others: Liquid fuel such as petrol, diesel, octane etc is still the dominant fuel for running vehicles. Kerosene in small extent is used for lighting and cooking. Burning of wood or dried leaves is quite insignificant in the city areas.

REMEDIAL MEASURES AGAINST ENERGY WASTAGE

IN THE POWER SECTOR Before delving into the ways that can improve the energy efficiency of a city, it is incumbent to give some glimpses of the energy losses and the possible solution outside a city. Firstly let us focus on the generation, transmission and the distribution side.

figure 4: A typical electrical power generation, transmission and distribution system. GENERATION SIDE Electrical power generation side consists of (in case thermal power stations) the generator unit along with various mechanical units such as turbine, boiler etc. Bangladesh is still dependent upon the old and outdated generator units. In the recent past, some private power companies have taken the initiative of installing power stations with

Expected gas reserve of the country = 23.09 trillion cubic feet

Recoverable amount = 13.7 trillion cubic feet

Amount of gas already used = 2.9 trillion cubic feet

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modern facilities, but still the overall picture is not up to the satisfactory level. ■ Generally, a generator unit has an effective life time of around twenty years. In Bangladesh there are generator units that are mostly older. That’s why these units are very often vulnerable to shut down or collapse and need replacement. On the other hand, proper maintenance schedule is not followed, resulting prolonged repair time whenever any breakdown occurs. For example, The unit 1 and 4 of Karnafuli Hydro Power station (40MW and 50MW respectively) has been under maintenance for around 7 months [2]. A unit in Khulna power station (60 MW) has been under going through maintenance for well around half a year [2]. In a nut shell the present scenario indicates that the maximum power generation in Bangladesh is significantly lagging behind the amount of installed capacity. All these data indicate that many of the generating units are outdated and hence are less efficient. Modern generating units are made from better core materials, precise control of fuel injection using microprocessors and hence have higher efficiency. With the development of new materials, turbine these days can withstand higher temperature and achieve better conversion efficiency. ■ New CCPPs (combined cycle power plants) should be installed. Usually, a gas turbine has a very low efficiency as the wastage of flu gas results in significant loss of heat energy. In a combined cycle power plant the flu gas of the gas turbine is used to run a smaller sized steam turbine to extract energy from the hot flu gas. Such a scheme improves the overall conversion efficiency by a significant margin. ■ The flu gas that is ejected to drive the turbine can be used to preheat water. This will save considerable amount of heat from being lost. ■ The power generation sectors should be privatized. The installation of modern power stations such as AES Haripur (120MW+240MW= 360MW) and also AES Meghnaghat (450 MW) (recently sold to British company CDC Globeleq) have proved to be quite efficient in its performance. Indian giant TATA Group has showed its interest in installing two 500MW power stations in Bangladesh. Such proposals should be encouraged and taken into account.

KEY STATISTIC Installed Capacity 4680 MW

Present Generation Capability 4368 MW Peak Demand Served so far(17TH Aug,03) 3592.1 MW Transmission Lines (230 & 132 kV) 3206 km

Grid Sub-Station Capacity (230 & 132 kV) 7202 MVA Distribution Lines (33 kV & Below) 41656 km Consumer Number (2002-2003) 1642474

Table 2: Key statistics of the electrical power sector of Bangladesh. ( Source: web portal of Bangladesh Power Development Board,

March 2004)

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TRANSMISSION & DISTRIBUTION: ■ Bangladesh Power development Board (BPDB) and Power Grid Company of Bangladesh (PGCB) have 230KV and 132KV transmission lines running across the country. With modern technology, it is possible to increase the high tension voltage even higher (400KV or 750KV), which will have much lower transmission loss. As the power consumption is increasing, the transmission line losses are increasing at a faster rate. ■ Modern transformers are made from better core materials to reduce core loss. Old and overloaded transformers should be replaced by new and better ones of correct rating having ample scope for future load expansion. Better maintenance of the transformers is necessary to keep the transformer losses at an acceptable level. In many areas the distribution transformers are seen where the transformer oil has not been replaced and the insulators are not checked for a long time. Therefore necessary monitoring of such power equipment is needed. ■ Low line voltage is a primary cause for higher system loss in a power system. Many of the electrical equipment like induction motor draw more current when the terminal voltage is lower. In Bangladesh, extremely high system loss (of the order of 30%) due to technical and non-technical reasons is the main reason for low efficiency distribution system. Non-technical loss like illegal connection of electricity puts undue pressure on the distribution feeders and the transformers. The other non-technical loss like non payment of the electricity bills encourage the corrupt users to abuse electricity usage and these factors in the long run make the distribution transformers overloaded and result in higher system loss and low system voltage. ■ Another proposal that may raise several eye brews is installing high voltage DC transmission links, which eliminates the possibility of any inductive or capacitive voltage losses. Though installation of such lines is incorporated with a huge investment due to the cost of the electronic circuitry such as inverters or converters, this area should be seriously studied whether it is cost effective or not in Bangladesh.

IMPROVING THE ENERGY EFFICIENCY OF A CITY Consumer Side Management: Consumer side management is the most important aspect of energy efficiency. Attitude of the consumers, their awareness and eagerness to use energy efficient gadgets play an important role in achieving high energy efficiency. The major energy efficiency issues of a city are summarized below.

1. Luminaries: With the increased energy consciousness of the city dwellers, people in the cities are using more and more energy efficient lamps. A fluorescent

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lamp is about five times more efficient than an incandescent lamp. So far the energy efficiency is concerned, significant energy saving is possible by replacing the conventional incandescent lamps by energy efficient lamps. A study from Philips Bangladesh Ltd. indicate that sale ratio of fluorescent to incandescent lamp is 1:7 [1]. Although city dwellers are more aware of energy efficiency, rural people predominantly use incandescent lamps due to the following reasons :

• high initial cost of the energy efficient lamps • low voltage problem • usage pattern

However, it should also be noted that the spectral response of human eye is such that human sense of brightness is better with the spectrum of an incandescent lamp. Hence, the effective saving of power from fluorescent lamp is about 3 times when compared to an incandescent lamp. A conventional fluorescent lamp is more expensive as it requires fitting and fixtures for the lamp and the lamp itself is also costlier. Although a Compact Fluorescent Lamp (CFL) is compact in size and can be used in the conventional holder of an incandescent lamp, cost per watt is still high. However, it is possible to recover the higher cost of conventional fluorescent lamps or CFLs within a year from reduced electricity bills. It is also noteworthy that using electronics ballasts for the fluorescent lamps can reduce the power consumption by 10W per lamp. However, electronics ballasts inject high frequency harmonics in the power system which increases the system loss from over heating of the transmission line due to skin effect and higher hysteresis loss in the transformers. High total harmonic distortion in a power system can also result in erratic behaviour of the protection system. Researches are going on to design ballast circuits with low harmonic distortion. In many of our city areas, people tend to avoid using fluorescent lamps or CFLs or face difficulty in starting them due to the problem of low voltage. If the supply voltage is lower than 190 volts, the starting circuit does not function properly and fluorescent lamps (that have conventional coil type ballasts) do not start. On the other hand, performance of electronic ballasts for fluorescent lamp or CFL is voltage sensitive that causes blackening of the lamp ends and premature failure when the terminal voltage is very low. Development of semiconductor technology has raised the hopes of using Light Emitting Diodes (LEDs) as commercially viable luminaries. An LED is a very high efficiency light source and is available with different colours. However, the high purity of the LED spectrum makes it uncomfortable for human eyes. Efforts are going on to incorporate LEDs of different colour within the same package to mitigate this problem. Like fluorescent lamps, LEDs are also extremely sensitive to voltage fluctuations and can get damaged very easily. Hence, electronically controlled rugged voltage regulators are needed for such lamps. Like the electronic ballasts for the fluorescent lamps, electronic controllers for the LEDs are also capable of injecting high frequency current into the system.

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2. Electrical drives: Electrical motors, are used to drive different types of domestic, commercial and industrial equipments. In house hold applications fans, refrigerators, washing machines, water pumps etc. use electric motors. Modern technology has improved the design and core material of the motors to reduce losses. At the same time power electronic controllers make the motors run at higher efficiencies. Although replacement of older motors, by new and efficient ones cannot be done overnight, all the encouragements should be there for the users to do so. Studies by the suppliers of motor drive systems (like SIEMENS) indicate that a power electronic control system for a variable speed motor can save as much as 30% of the energy consumed. A recent research on the torque speed performance of induction motor shows that low cost induction motors can be designed whose torque-speed characteristics are self adaptive to produce higher torque by changing the rotor resistance automatically [3]. Such a design is very important for compressor motors, otherwise they may stall and draw excessive current under low voltage condition. In many situations the motor may even be damaged. 3. Proper building design for efficient air cooling system: Most of our commercial buildings are designed to house air conditioning systems. All the design arrangements are made for the placement of the chillers, ducting for the coolants and power line for the compressors. But in most of the cases, proper importance on the thermal insulation of the building is ignored. Although, thermal insulation will increase the cost of construction, it pays off in the reduction of electricity bills, as air cooling is a major energy consumer in the commercial buildings. 4. Power Factor Improvement (PFI) plants: All the commercial and industrial are required to install their own PFI plants to keep the power factor high. PFI plants keep the current consumption low resulting in better line voltage. However, there are still flaws and loop holes in supervision of the PFI plants and many users bypass the installation of PFI plants by illegal means. It should be noted that most of loads are either resistive or inductive in nature. Researches should be encouraged to look into the possibility of devising capacitive loads. As for example, a research was carried out in the Department of EEE, BUET to develop capacitive ballast for fluorescent lamps [4]. Such ballasts enhance the efficiency of the fluorescent lamp circuit and are less sensitive to voltage fluctuations. As lighting load in a commercial or industrial installation is significant, capacitive ballasts can reduce the size of the PFI plants and enhance energy efficiency of the overall system. 5. Smart Systems: Smart systems can be adopted in the commercial or industrial sectors to control load automatically using microprocessors and sensors. As for example, in an office building or a hotel, air conditioners and lights can be automatically switched off when no body is in the room. Corridor or passage lights can be switched OFF during off peak office hours and switches ON automatically when some body enters the passage.

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Controlling of street lights is another example of smart systems. At night after 12 o’clock, street lights can be switched off alternately, as the traffic density reduces. 6. Harmonic Reduction: Many of the modern electronic and power electronic gadgets like, Television, computer, inverters for motors generate significant amount of harmonics which is injected into the system. Most of these devices draw current spikes near the peak voltage of the supply sine wave and causes excessive voltage drop near the peak. This phenomenon causes peak flattening in almost all the developed countries as they have very high usage of electronic gadgets. Such a distortion in the voltage wave shape propagates to all other loads connected to the system and injection of current harmonics multiply. Harmonic performance of the popular electronic gadgets should be carefully monitored and poor quality gadgets should be banned before much damage is done to the power system. 7. Supply of hot water: Hot water is widely used by almost all domestic users and a large number of commercial or industrial users. For domestic users, a small heat exchanger acting as a hood at a convenient height from the gas cooker can be quite effective in preheating the hot water required for dish washing or bathing. In large hotels, huge amount of heat is released in the air from the air cooling system. This heat can be collected using heat exchangers and can preheat the hot water, which is an essential component in a hotel. Such an arrangement will reduce the cost of water heating and at the same time reduce electricity consumption for air cooler as the heat exchanger will remove heat at a faster rate. 8. People’s attitude towards energy efficient equipments: Awareness about energy efficiency is gradually increasing among the city dwellers. Most of the metered households use energy efficient lamps and avoid high energy consuming gadgets like electric heaters. The main hurdle in implementing energy efficient equipments is the initial cost. Besides, reduction of non-technical system loss is essential for successful implementation of any energy efficiency drive. Some one who does not pay for the energy bills does not care for energy saving. A number of studies were made in 2003 regarding the attitude and awareness of the consumers regarding energy efficiency [1] 9. Day light saving by changing office hours: The dawn to dusk hours in Bangladesh do not changes by large amount like the European or the North American countries. The time span for day is about 14 hours in summer and 10 hours in winter. It may be possible to have some daylight saving but it does not look very attractive on the first look. However, appropriate study is needed to reach a conclusion in this respect. 10. Better Traffic Control on the Roads: A major problem that has been prevailing in the cities for a long time is severe traffic congestion. A significant

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amount of fuel is wasted from the vehicles while waiting in the congestion. Drastic measures to eliminate non-mechanized vehicles like rickshaws, imposition of strict traffic rules, more effective fitness test for the vehicles and steps to reduce corruption in issuing vehicle fitness certificates, and better training of the traffic wardens are needed. Better efficiency on the roads can possibly save enough money to build more flyovers in cities to reduce the traffic congestion even further. 11. Gas Metering for All Users: Domestic users in Bangladesh are mostly billed for their gas usage depending on the number of burners and ovens they use. Such a tariff policy encourages users to keep their burners on even when the cooker is not in use. Connecting gas meters would greatly reduce this malpractice and save significant gas consumption. Instead of providing gas connection to the domestic consumers, gas cylinder usage should be encouraged to reduce pilferage and non payment of gas bills.

CONCLUSIONS To make energy efficiency program a success, cooperation from all the sectors are important. Awareness amongst all types of consumers is necessary to increase overall energy efficiency. At the same time drastic measures for reduction in the system loss, proper tariff structure and taxation policy also plays an important role in this respect. In appropriate sectors, banks and financial institutions should be encouraged to provide loan for energy efficiency projects.

BIBLIOGRAPHY:

1. “Preliminary Study on the Awareness and Financing of Energy Efficiency Projects in Bangladesh” – for SARIE/AED , Report prepared in 2003 by M. Rezwan Khan, Md. Aynal Haque, M. Mahmud Sohul.

2. Daily 8:00 AM Report from Central Load Despatch Centre , reporting date 04-Mar-04

(page 2). (Collected from the web portal of Bangladesh Power Development Board, BPDB)

3. M. Rezwan Khan, I Husain and M.F. Momen, ‘Lightly Ferromagnetic Rotor Bars for

Three-Phase Squirrel Cage Induction Machines’, IEEE Transactions on Industry Applications, Volume 40, Issue 6, Nov.-Dec. 2004 Page(s):1536 – 1540

4. “Design and construction of low loss semi-electronic ballast for fluorescent mercury

vapour lamps” , M. Rezwan Khan, Dept. of EEE, BUET, BRTC Report, BUET, 1989.