The Challenges and Opportunities of Centralised and Decentralised Biodigesters

The STEPs research project explores the relative benefits and dis-benefits of larger centralised biogas systems at a village scale versus smaller family-scale systems. It also investigates the economic and financing factors (centralisation brings economies of scale but can only really be implemented by organisations/governments, family-scale systems may be out of reach of user capital without financing arrangements), environmental factors, and social and behavioural considerations (do users want to collectively cook, issues with economics of pipe gas supply meaning necessity of group facilities etc) inherent in biodigester development.

Biogas digesters can be a valuable solution to providing thermal energy services to rural and urban households in the developing world. The technology is particularly applicable in rural areas, where access to feed stock for the digesting chamber in the form of agricultural wastes and other organic wastes is greater. In general, digesters fall into two broad categories: household-scale biodigesters, and larger, centralised biodigesters.

Dome-type biodigester in Arusha, Tanzania [1]

Household-scale biodigesters are often seen as the most viable option for rural communities and households. These are generally small, with digesting chambers of volumes in the 4 to 13 cubic metres range. These installations will support the cooking needs of a rural household, as well as providing biogas for heating or lighting if required. Tailoring the size of the biogas system to the availability of feedstock for the household is critical for successful functioning of the system: studies have suggested 4-6 heads of cattle is a sustainable target if using agricultural wastes for feedstock, for an average-sized family of five. Individual biodigesters can produce sufficient gas for a single person on as little as 1 kg/day of feedstock.[2]

However, one of the primary limiting factors in the adoption of household biodigesters is financing and end-user capital constraints. Household-scale systems are still relatively expensive for the majority of rural developing-world users, and experience has shown that without the provision of credit facilities in biodigester programs, or government subsidies, adoption rates remain low.

Centralised biodigester systems offer a different set of benefits and challenges. Economies of scale are the major advantage: one centralised system can serve a medium-scale settlement or several small settlements, with a reduced burden for upfront capital costs and maintenance compared to the same service with household-scale systems, in the range of US$100 – 500 per household. The Chinese National Biogas Program [which will be the subject of a later blog in this series], has been the major implementer of centralised systems, however experience also exists in other South-East Asian countries. Examples of this can be found in the centralised digesters built near Beijing to service rural villages. For an upfront cost of ~US$1 million, 1900 households are serviced through each centralised digester, with biogas available at a 20% discount compared to market LPG prices, and the additional benefit of organic effluent being made available for sale to the local farms feeding the digester.[2] The major constraint, however, to wider dissemination of centralised systems is the significantly higher up-front capital costs. This puts the systems out of reach for private users in the majority of cases, government-scale implementation is more common.

Socio-political conditions are another factor that has proved a constraint in biogas implementation projects in developing countries. Centralised biogas digesters can have difficulty with biogas supply to end-users, particularly given the poor economics of installing piped gas supply in small rural communities. Communal cooking facilities have been a solution to this problem in theory, however experience from India suggests that collective cooking is not desired by the rural population, and this has impacted upon the success of centralised digester installations. As with dissemination programs for clean cookstoves, biogas installations need to take into account the end-users needs and desires in design and installation for product use and performance.

The other posts in this series will cover the question of why biogas hasn’t succeeded in Sub-Saharan Africa as it has in South-East Asia, the maintenance question for biogas services, and lessons from the Chinese National Biogas Program.

– Xavier Lemaire & Daniel Kerr, UCL Energy Institute

[1] Laramee & Davis (2013) Economic and environmental impacts of domestic bio-digesters: Evidence from Arusha, Tanzania. http://dx.doi.org/10.1016/j.esd.2013.02.001

[2] Hojnacki et al, MIT (2011) Biodigester Global Case Studies. Available at: https://colab.mit.edu/sites/default/files/D_Lab_Waste_Biodigester_Case_Studies_Report.pdf

SMEs and Clean Energy for Emerging Markets Event – London, UK

STEPs project partners attended an event, jointly run by the DECC, Knowledge Transfer Network, Loughborough University, the LCEDN and the UKCDS, entitled “SMEs and clean energy for emerging markets: challenges and opportunities”. This event was held on the 29th September 2014 at the Wellcome Trust, London, UK. This event sought to bring together representatives from the academic, government, non-government and private sectors, to discuss the current situation, opportunities and challenges to the growth of small and medium enterprise in the clean energy sector for developing economies. Several plenary sessions were held over the course of the day, and stalls were also present from a wide range of institutions, organisations and companies, including Xavier Lemaire and Daniel Kerr from UCL, presenting the STEPs project.

The day began with an establishing session on the global opportunities for SME development in emerging markets. Presenters from Knowledge Transfer Networks Ltd, SolarCentury and SolarAid highlighted a number of challenges facing clean energy provision in markets globally, particularly in developing economies. These ranged from the challenges of replacing aging infrastructure in developed economies, to those of reaching consumers in poverty in rural areas of developing countries. Consistently highlighted were the sobering figures accepted by the international community on energy access: with over 1 billion people still lacking electricity access, and 2.6 billion projected to lack clean thermal energy access by 2020, the presenters made clear the vast potential for SMEs to bridge the gap in energy services provision to emerging markets.

Following this was a session on innovation in energy services for emerging economies. The presenters, representing X-wind, Buffalo Grid and Renovagen, were all private-sector participants in the event, being entrepreneurs involved in SMEs for clean energy development. The presentations focused on the efforts of the companies to develop products and services for emerging markets. X-wind is a company producing resilient, vertical-axis wind turbines for community-scale deployment. Buffalo Grid produces pay-as-you-go solar-powered electricity and wireless internet base stations for deployment in off-grid communities. Renovagen is a new start-up producing fast-deploying PV micro-grids for off-grid communities, as well as in disaster relief and industrial applications, based on a novel flexible PV array. These organisations shared a number of features: all were looking to expand energy services access in developing economies, and they also all identified the need to tailor the product or service to the challenges of emerging market contexts. For example, resilience was a key feature of X-wind turbines, with low maintenance requirements improving reliability. The prevalence of mobile connectivity in the developing world, particularly Sub-Saharan Africa, was also incorporated into the Buffalo Grid product design, with mobile charging being identified as a key service to offer for increased take-up of the product. This point was also discussed in more detail in the fourth session.

Participants were encouraged to network over lunch and visit the presentation booths. The STEPs project booth received a good amount of interest from researchers and entrepreneurs interested in thermal energy access, and business models for energy access more broadly.

The third plenary session focused on financing and support for SMEs, and access to finance. Representatives from the Shell Foundation, UKTI and Enclude Capital Advisory presented on available and appropriate financing routes and the challenges to financial access in emerging markets, as well as the support available for SMEs from financial, governmental and non-governmental institutions. Appropriate finance for SMEs was a key point of the presentations. In the design of financing mechanisms for small and medium enterprise in developing countries, the type of financial assistance can have a significant effect on the impact of the financing on the company, particularly in transition points between sizes of companies. For example, donor funding is most useful to start-up companies that may not be able to afford market loans for growth, whereas commercial or governmental loans/financing schemes are more useful to more established organisations.

The fourth session sought to clarify the realities of energy services for emerging economies through presentations from a number of organisations and companies with experience in emerging market projects, ranging from humanitarian and aid-sector solar lighting organisations to distributed wind generation providers. Two themes were recurrent in the presentations: the necessity of assessing the nuances of the local and regional market in designing products and services for emerging markets, and the huge potential to be found in integrating products and services in a ‘smart’ fashion, most notably through the use of mobile technology. Mobile signal access has developed significantly faster than electricity access in many emerging markets, and with the immense success of the M-PESA and M-KOPA systems, integrating financial transactions into mobile systems has been proven to be a workable business model. The design of clean energy products is also key to their success in supplanting established traditional technologies in emerging markets. This can be as simple as reducing the height of a cookstove so that it can be used more easily, but can have a significant impact on market penetration.

The final session of the day focused on the impact that academic research and evidence can have in supporting the activities of SMEs working in emerging economies. Speakers from SolarAid, Oxford University’s Power and Energy Group and DFID engaged in discussions with the room on how academic research can assist in the design of business models and market research for SMEs, as well as in simulation, social and demographic analysis and other areas. The concept of innovation synergies with academic research was also highlighted, with the academic sector being able to assist in all stages of product and service development, from needs assessment to testing and evaluation of products, to effective deployment strategies and models.

– Daniel Kerr, UCl Energy Institute