Biogas and Rain water Harvesting

Lessons and Opportunities for

FONERWA

DRAFT

August 2015

Prepared by:Gerard HendriksenConsultant

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1 IntroductionThis analytical note has been prepared for FONERWA management and is an assessment of the spread of the use biogas and rain water harvesting (RWH) technologies in Rwanda. The note uses much of the information presented in the technical briefings on the two technologies which are intended to guide project applications and evaluators to respectively design and evaluate proposals. This analytical note is prepared to assist the FONERWA management in better understanding of the biogas and RWH potential in Rwanda, to draw upon lessons from the region and to recognise opportunities for the two technologies.

Chapters two and four provide summaries of the biogas and RWH technologies and their status in Rwanda respectively. Chapters three and five highlight some of the strategic opportunities for FONERWA as identified by the consultant. These could be assist in the consultations and discussions between FONERWA, the Rwandan Government and development partners on the future direction of the programme.

2 Biogas 2.1 Biogas and its applications in Rwanda

Biogas was introduced in Rwanda in the 1980s. The technology gained international attention after large systems were installed in the prisons starting from 2000 onwards. The technology helped to clean the environment around the prions and produced gas for cooking reducing fuel wood consumption. The National Domestic Biogas Programme with support of GIZ and SNV became operational in 2007 and focussed on digesters for households with 2/3 dairy cows. About 5,500 digesters have been installed but the target is an ambitious 100,000 units by 2018. Donor support ended in 2011 and the Government now fully supports the programme and provides subsidies for installed units. The Government also has equipped all prisons and a good number of board schools with large biogas systems and efforts are continuing. Communal biogas systems using cow dung and/or toilet waste were installed in few places including in some “green villages”.

The table gives an overview of the types of biogas systems that are installed in the country, the main applications and indications of expected lifetime and investments costs per m3 of digester volume. .

Table: Overview of biogas systems for Rwanda

Technology/ Sizematerials

Main application

Expected life time 1)

Rwf per m3

digester

Dom

estic

Fixed dome 4 – 10 m3

Made out of bricks, stones, cement

Rural house- holds with 2-3 dairy cows and more

15 - 20 years plus

100 – 150,000

Prefabricated digesters 4 – 6 m3

made out of plastic and/ or fibre As above 10 – 20 years 90 - 125,000

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Technology/ Sizematerials

Main application

Expected life time 1)

Rwf per m3

digesterapplications

glass, importedFlexi biogas bags 5 – 7 m3

Made from imported canvas materials

As above 5 – 10 years 80,000

Plastic tanks 0.5 – 2 m3

(urban use)Poly ethylene

Urban house-holds producing gas from organic kitchen waste

5- 10 years plus

200 – 400,000

Larg

e sc

ale

Prison/ school biogas systems25 m3 and plus

Fixed dome typebricks, stones, cement, steel

Boarding schools

15 - 20 years plus

375 – 600,000(including

toilets)

Communal systems, 25m3

Fixed dome typebricks, stones, cement, steel

Green Villages

15 - 20 years plus

Combined with biogas

Note: 1) Estimates for expected life based on expectations as real figures are not yet available

for most of these technologies 2) The plastic digesters for urban use have not yet been introduced tested in Rwanda but

data are based on experiences in Tanzania.

2.2 Small biogas digesters for domestic applications2.2.1 Fixed Dome DigestersThe fixed dome digester is the most common type. NDBP has supported about 5,500 units since 2008. The programme is market driven; farmers engage with local contractors trained by NDBP and they construct the digester at the farmer’s location using bricks, cement and other locally available building materials.

Sizes of the digester vary between 4 and 10 m3 but the most popular model is 6 m3. It requires about 40 kg of fresh cow dung per day (2 – 3 cows using zero grazing) and a similar amount of water or urine collected from the stables. Toilets can also be connected to the digester and this will increase gas and bioslurry production, whilst helping to clean the environment. However, it has proven difficult to

motivate the households to connect their toilets.

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Fig: Fixed dome digester

The 6 m3 digester generally provides sufficient cooking gas for a family of 4-5 persons. Local contractors can built these digesters in a matter of weeks at a costs of Rwf 625 – 800,000 (Rwf 110 – 140,000/m3). Construction costs have gradually reduced since 2008 and there remains little scope for more savings. The Government through NDBP provides a subsidy of Rwf 300,000 per digester. Districts authorities include biogas in their annual development plan.

2.2.2 Prefabricated DigestersOver the years there have been several attempts to introduce pre-fabricated digesters to ensure uniform standards and quality and also quicker installation. NDBP tested about 100 Chinese made PVC digesters in Kirehe district in 2008/09 but the technology did not take off. Simgas from Tanzania is developing and testing a different and modular design. Market prices are expected to be close to the concrete fixed dome type.

Flexi bag digesters have been manufactured and sold in Kenya for over 10 years. In 2012 the KWAMP programme in Kirehe introduced these digesters made from heavy duty canvas and protected by greenhouse type tunnel. Since then the market has developed fast and between KWAMP and NDBP close to 1,000 thousand digesters are currently in operation (NDBP verbal communication). Prices are Rwf 400,000 and the Government provides a subsidy from Rwf 300,000, similar to the fixed dome type. Installation is much quicker compared to the

masonry types and farmers can relocate the flexi bag if needed. Performance is claimed to be good, partly because of the higher temperatures generated by thee green house. Life expectancy is probably 5 – 10 years but that still has to be proven.

2.2.3 Digesters for urban areas Biogas can also be produced from food waste and especially in urban areas this could be an option as organic waste is available and the costs of charcoal is relatively high. The technology has been tested and promoted in Tanzania by ARTI (from India) and by SimGas. The biogas digesters made out of adapted black water tanks with capacity of 0.5 and 2 m3 were sold in Dar es Salaam for approximately USD 325 and 550 respectively including installation.

Despite success stories on the internet of urban biogas in China and India, sales in Tanzania were disappointing and both companies have since stopped their programme.

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Fig: Flexi Bag full of gas, inside greenhouse tunnel

Fig: ARTI biogas digester for organic waste

2.3 Larger and commercial applications of biogas2.3.1 Digesters for prisons and schools and The Government has installed large biogas systems in all prisons to reduce consumption of firewood (up to 40% is reported) but also to mitigate the impacts of the toilet waste around the institutions. There are also a good number of schools in the country that have adopted the technology. A survey in 2009 showed that these systems functioned best where there is a strong and committed management (mission schools did particular well) and in combination with dairy cattle to provide more feeding materials as well as a supply during the school breaks.

There is a still considerable potential to install biogas in schools and other institutions such as army camps. These large digesters vary in size between 25 and 50m3 and are often constructed in series to get larger capacities. The digesters are constructed out of bricks, cement and other building materials fairly similar to the fixed dome type for domestic use but additional skills of the artisans are needed. Investments costs vary considerably as these digesters are constructed individually, are location specific and often involve the building of new toilets and other accessories.

The AfDB PNEAR project estimated the costs for a complete 2*30 m3 system at Rwf 35m. About Rwf 7 m or 20% was for the building of new toilet blocks. The system was designed to serve a school of about 450 students and to reduce the fuel consumption by an estimated 50%. Per m3 digester capacity the costs are about Rwf 450,000 which looks to be very high. Unit prices for large biogas systems are consistently higher than for the NDBP promoted fixed dome digesters which are Rwf 110 – 150,000 and have much in common in design and materials used. It appears that the market for domestic digesters is more competitive than for schools.

2.3.2 Communal biogas systemsCommunal biogas systems bring the toilet waste and cow dung from several houses to one larger digester and the gas is distributed to the families involved. Few of those systems have been installed in selected Green Villages. There is little detailed information on the costs of these systems but these appear to be significantly higher than for the fixed dome digesters installed under the NDBP in individual households. The City of Kigali has in the past also installed communal digesters in Kagugu low costs housing estate.

Biogas digesters that only use human waste have limited production of biogas and the deliver about 20% of the daily cooking gas requirement for the family. Therefore combinations with dung with dairy cows or other animal dung is recommended to increase gas production.

2.3.3 Biogas for electricity generationBiogas can be used for electricity generation. Commercial applications in Europe and other countries involve large quantities of biomass or organic waste and often these systems are heavily subsidized. Uptake in Africa has so far been limited. UNIDO has supported some smaller applications in Kenya, Tanzania and also in Rwanda (Green Hills School in Kigali tested in 2009/10 a 5 kW generator to operate on kitchen waste). However, these small installations proved complicated to operate and the technology is no longer promoted.

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Commercial opportunities in Rwanda include the capture of methane gas from municipal waste sites (provided these are designed for this purpose), agricultural food processing plants including the breweries and large dairy, chicken and pigs farms where there is an access of manure.

2.4 Some other benefits of biogas Bio-slurry is a by-product of the digester which is claimed to have high value as natural fertiliser. However, results of various studies vary widely but there is a consensus that the get maximum benefit of slurry special extension efforts are needed

Carbon credit can be obtained as biogas reduces greenhouse gas emissions. This can become an additional source of revenue to sustain the biogas programmes. The NDBP project calculated an average reduction of 5.7 tCO2/year for a 6 m3 digester. The initial costs of developing such carbon credit programmes were high but these reduced through the so called Programme of Action approach which can combine several smaller projects. SNV’s Africa Biogas Partner Programme is preparing a voluntary carbon scheme which could also be of benefit for the Rwanda domestic biogas programme.

3 Opportunities for strategic interventions for biogasBiogas is already well known in Rwanda mainly thanks to the efforts of the Government for the last two decades. However, despite these successes, more is needed and EDPRS2 specifically mentions the biogas programmes for households and for institutions as an alternative source for cooking energy under priority area four “Connecting Rural Communities to Economic Opportunities through Improved Infrastructure”. FONERWA can support these Government targets but should be strategic in it choices as investments costs in biogas are high and there is a need to leverage funding from other sources. Interventions may include studies and market surveys that will encourage other players to come in, using their own resources or in a partnership with FONERWA and other funding sources. The other option is the use of targeted call for proposals to stimulate new and innovative approaches which can be game changer in the longer term. However, that will require FONERWA to accept more risks than in the case of supporting proven concepts.

The NDBP already covers promotion of domestic biogas in the rural areas for households with 2/3 or more cows. There is scope to increase the implementation rate of this programme but much depends on the engagement of the districts and if the Government can sustain the current subsidy levels (Rwf 300,000 per digester). It is not a sector where FONERWA can make a significant contribution.

Some interventions that are worth considering are:

1) Assess the opportunities for biogas in urban areas using kitchen and other organic waste. This will require testing of possible options for Rwanda, enterprises that can install and maintain the equipment. Subsidies for

2) Studies to arrive at a better understanding of the costs of institutional biogas and to identify ways of reducing those costs. This may also include a comparison between communal and individual biogas systems in terms of costs and benefits.

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3) Promotion of results based financing for large biogas installations whereby the contractor is (partly) rewarded for units of gas delivered and hereby transferring the operation and management to a specialised company. This will also allow carbon credits to be included and contribute towards financial sustainability.

4) Programme or incentives to increase the use of toilet waste as a feeding material for biogas, in particular in the domestic installations in the rural areas.

5) Potential of biogas for waste water treatment. This will require a close collaboration with WASAC to assess the technical opportunities, financial implications as well role of private sector in this area.

6) Assessment of the potential for larger scale and commercial production of biogas for process heat and electricity generation using agricultural and other organic waste materials.

7) Potential of carbon credits for biogas installations. NDBP has worked on this for the domestic biogas but so far no carbon program has been developed.

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4 Rainwater Harvesting 4.1 Access to water in Rwanda and role of RWH

The Third Integrated Household Living Conditions Survey (EICV3) of 2011 reports that 74.2% of the population in Rwanda has access to an improved source of drinking water (urban 86.4% and rural 72.1%). The Government wants to reach 100% by 2018. The EICV reports that 0.4% of the population uses rainwater as main source of drinking water. The RNRA baseline survey carried out in 2013 for their RWH project interviewed over 1200 users (households and businesses) and reports that 28.6% of the population is using rainwater as their source of water. The reason for this large difference between the two surveys is not clear and requires further investigation.

The water and sanitation policy recommends rain water harvesting as a complementary source of water in areas that could otherwise only be supplied by pumping at excessive costs (e.g. hilltop locations, lava region). The policy does mention that rain water harvesting cannot fully replace normal water supply systems especially during dry seasons. Some districts have included RWH in their development plans bot both public buildings as domestic houses.

Rain water harvesting is a relatively simple technology and can be constructed using locally available materials and skills. Maintenance is simple and costs are low. The collected rain water can be consumed without treatment provided that a clean surface is used for collection. It provides a supply of safe water close to homes, schools and clinics. The benefits of RWH to the users include:

1) Reduction of time required for collecting water. In rural areas household spend an average of 29 minutes per day on fetching water and 9 minutes in urban areas.

2) Reduction in costs of buying water. The annual savings can be about Rwf 35,000 for an average household.

3) Availability of additional water which can be used for domestic purposes but also opens opportunities for increased household gardening, livestock care, etc

4) Health benefits of additional water supply as it may influence hygiene.

The effects of RWH on erosion control is often mentioned because of reduced run off from roofs. There are however no clear measurements in place to assess these impacts and the amount of water collected/sored is relatively small to the rainfall, in particular during down pours when potential for erosion is biggest.

Impact on WASAC is not obvious. The company will lose revenue from water sales as RWH spreads but at same time there will be a reduction in operating costs, for instance less electricity needed for the pumping stations. On the other hand, WASAC needs to ensure water for the population over the full year, including the dry season when domestic tanks run dry. It will therefore have to continue to invest in infrastructure while losing some of its revenue.

4.2 Water demand and storage capacityOne of the critical issues in RWH is to determine the user’s demand and the corresponding capacity of the storage reservoir, especially during the dry season from June to mid-September. The ADB water harvesting handbook estimates daily water demand to be 25 – 40 litre/day per person. Based on these simple figures, the total storage capacity for a household of five persons would be between 4 – 5 m3 to last for one month. However, these

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figures are only indicative and are influenced by local rainfall patterns, family’s preference and other uses of water for livestock (one dairy cow requires about 20 litres of water per day) and homestead gardening for instance.

For large public buildings the MININFRA RWH study of 2010 recommends a software package (RainCycle) to calculate storage needs and this takes into account the rainfall data, daily demand of water, type and size of roof, and number of days acceptable without rain water.

4.3 Costs of storage reservoirs, gutters and piping

4.3.1 Different types of reservoirs and their unit costsThe table below provides basic information on sizes and costs per unit of cubic meter for the different types of reservoirs that are commonly used for RWH both in large public buildings as well as domestic houses. Basically the reservoirs can be divided into

Constructed in situ by contractors using bricks, stones, cements, iron bars etc

Pre-fabricated tanks bought from hardware dealers, installed in short time and removed/ replaced/ added if needed.

Table : Types of reservoirs and their main characteristics

Description Storage Costs range

In si

tu Ferro cement tanks 10 – 100 m3 150 – 200,000/m3Brick/masonry tanks 5 – 30 m3 150,000 /m3Artisanal tank with 6 m3 20,000/m3

Pre

fab Metal tanks 1 – 10 m3 160,000 / m3

Fibre glass tanks 2 – 75 m3 220,000/ m3Polyethylene tanks 0.5 – 10 m3 130,000 /m3Jerricans 20 litre 125,000/m3

Adapted from RNRA Project Document and MININFRA RWH study of Public Buildings

The polyethylene tanks (mostly black in colour) have become the popular choice over the last years and have practically taken over from the metal and fibre glass tanks. Costs of these tanks in Rwanda appear higher than for instance in Tanzania where a 5m3 plastic tank is sold for the equivalent of Rwf 250,000. It would be good to look into the cost structure of these products to see if there is scope for further reduction. At the meantime, jerricans continue to be the preferred option for many households as well as in public places, according to the RNRA baseline survey. The costs per volume of water stored is comparable to larger water tanks but their scalability and flexibility are probably reasons for their popularity.

The RNRA project provides some information on the costs of gutters. The most popular systems use plastic or metal gutters ranging from Rwf 6,000 to 8,500 per meter length. Some people opt for the cheaper option of cutting and bending iron roofing sheets and these are estimated at Rwf 4,500 per meter.

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4.3.2 RWH for domestic houseThe typical costs for a domestic house are estimated at approximately Rwf 700,000. The highest costs are for the plastic water tank of 5 m3 capacity costing about Rwf 450,000. The rest is for foundation, guttering and some other materials. Plastic tanks offer the advantage that they can be bought in small sizes at approximately same costs per unit. That makes it easy for households to start with a smaller tank and add more units if needed and they have the finances.

In rural areas there is also the opportunity to construct low cost storage reservoir made out of bricks with a plastic liner. These artisanal tanks have been widely adopted by the population in the Shangasha Sector of Gicumbi District (the report mentions that 90% of the households were using the system).

The costs of an artisanal tank of 6000 litre varies between Rwf 80,000 to 100,000 which means 20% and less than same size plastic water tanks. The RNRA RWH project supports families in the lower household group and provides them with the plastic liner and roofing sheets for the cover.

Figure 1: Artisanal water reservoir (Shangasha) under construction and completed with roof

The estimate of the financial benefits of RWH for households is based on data from the RNRA baseline survey of 2013 which reported an average costs of Rwf 45 per jerrican and total expenses of Rwf 2,920 per month. This means a consumption of about 2 jerry cans/day or 65 jerricans per month or about 1500 litres of water per months, far below the 4 – 5000 litre recommended by the ADB RWH handbook) For families using RWH the baseline found an average savings of Rwf 1,200/month. Assuming that the RWH system will supply 100% of the household’s water requirements, the annual savings would be about Rwf 35,000 (two jerricans/day over 365 days and Rwf 45 per jerrican).

Payback time depends on the capital and operating costs. In case of an investment of Rwf 0.7 m for a domestic system as described above, the payback time would be about 20 years not calculating interest rates and operating. There are clearly other advantages than just the financial benefits which motivate households to install RWH as mentioned above. Financial support through subsidies (like provided under the RNRA project) and/or access to affordable credit maybe be needed to speed up the dissemination of domestic RWH systems. To justify such support, a better understanding is needed of the other additional benefits of RWH including improved health and sanitation, reduced workload for women and children, impacts

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on education and opportunities for income generation through kitchen gardening and livestock keeping.

For rural areas where the construction of the low cost, artisanal reservoirs is feasible, the financial returns on investments are much bigger and this is further aided by the opportunities for livestock and gardening.

4.3.3 RWH for public buildingsMININFRA’s feasibility study of rainwater collection for public buildings provides much technical information and indicative costs of the various systems. The study estimated that would require an investment of Rwf 28 billion to equip all 777 identified public buildings with rain water storage systems. The main characteristics of these RWHs are given in the following table.

Table: Type of RWH for public buildings and their main elements

Type of public building RWH main elementsHigh rise buildings

(17 reported)

Roof area 500 – 1,000 m2

Flat roofs, cementedUnderground reservoirsPump to bring water to header tank on the roofEstimated average costs: Rwf 50 m

Large buildings

(380 reported)

Roof area 1,200 to 6,000 m2

Iron sheet roofsSchools, health centres, markets, district officesLarge storage; under of above groundWater pumped back to roof tank or direct through pipe networkEstimated average costs: Rwf 65 m

Small buildings

(380 reported)

Roof area 100 – 500 m2

Iron sheet roofsAbove ground tanks: cement or plasticEstimated average costs: Rwf 10 m

5 Opportunities for strategic interventions for RWHRWH is a simple technology and skills and materials for constructing RWH are widely available in particular for the domestic sector. RWH can greatly improve the access to water especially in areas where the utility company has little or no infrastructure (as yet). This is mainly in the rural areas where public taps, springs or other sources can be far away.

RWH contributes towards FONERWA’s programme objective of adoption of environmentally sustainable, low carbon and climate resilient technologies in Rwanda, increased resilience towards climate change and the creation of green jobs. Also RWH is already well integrated in the national development planning as means to increase access to water. The question is how FONERWA can make a strategic difference in promoting RWH technologies and leveraging funds from other sources such as

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the households that are interested to invest, private sector producing and distributing RWH equipment and financial institutions that are willing to support with credit.

FONERWA can support further development and promotion of RWH through some strategic interventions that complement or support existing or new players in the sector. These may include studies and market surveys or calls for proposals targeting specific outcomes.

Opportunities for FONERWA to consider are:

1) Focus on rural areas where economic returns for RWH are higher than in urban areas as distances to water sources are generally larger and there more opportunities for other beneficial activities such as livestock keeping and home stead gardening.

2) Investigate the costs/benefits of communal RWH versus household solutions to guide future public investments in these technologies

3) Market survey in the costs of RWH equipment in particular the plastic water storage tanks, piping etc which are the largest costs factors in domestic RWH and opportunities to reduce costs

4) Establishment of regulations for integration of RWH in public buildings and large commercial properties and in combination with WASAC in order to reduce overall investment costs.

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