Siem Reap, home of the Angkor Watt temples, is among Cambodia's poorest provinces . Four out of ten villages lack access to clean drinking water; literacy rates are among the lowest in the country; 53 percent of all children are malnourished, and average incomes hover just above $1.80 USD per day . The tourism industry here brings in over $640 million USD per year, yet foreign revenue streams do not ensure (and may indeed extract from) local development -- though the draw of external revenue streams is understandably attractive for Least Developed Countries such as Cambodia.
But a different form of foreign investment has dramatically changed Arun and Mlis Keo's  economic outlook. The couple, who farms just 20 kilometers from the Angkor Watt heritage site, acquired a biodigester through the National Biodigester Program (NBP) run by the Ministry of Agriculture, Forestry and Fisheries of the Cambodian Royal Kingdom (MAFF) and the Netherlands Development Organisation (SNV-Cambodia). The biodigester, which converts livestock dung to biogas, fuels their cooking and household lighting needs and has decreased their energy bill by $14.39 per month -- while saving them one and a half hours per day in fuelwood collection. The slurry waste from the biodigestion process substitutes for chemical fertilizer, generating an extra annual savings of $52 per year.
The Keo family represents just one of 8,000 Cambodian rural homes, spanning nine provinces, that have qualified for a flat $150 subsidy and soft private loans to invest an average of $472 into a household-scale biodigester. Considering that the average annual Khmer income is $412, the NBP's popularity (and zero loan-default rate) deserves investigating .
When talking about the biodigester, the Keos do not mention the environmental or health benefits of the project. The best part of owning a biodigester is the convenience, Mlis Keo said. She no longer needs to collect firewood or buy charcoal, and cooking rice on a gas stove is much easier than building and maintaining a fire.
But reductions in household soot and atmospheric methane from the livestock waste are certainly points of interest for NBP, which is trying to convert those benefits to carbon credits for international sale.
Carbon finance -- foreign investment in greenhouse-gas-reducing projects in developing countries that generate, in turn, carbon credits that developed countries may buy and use for their own climate commitments -- has been a source of controversy in international headlines and academic debate since the Kyoto Protocol launched a global carbon market in 2005. Proponents point to an estimated $141.9 billion market value in 2010  while critics underscore imbalanced regional investment patterns  and uncertainty regarding the final destination of the revenue streams.
While much has been said on the shortcomings of carbon finance, the market's local successes are poorly understood and may, in fact, be hindered by current market rules. Further, while the future of the Kyoto Protocol is uncertain, international enthusiasm for carbon-financed cookstove programs is on the rise with the launch of the Global Alliance for Clean Cookstoves. But how can carbon finance truly benefit the poor? And are current requirements for defining a carbon offset project relevant for development objectives?
These are just a few of the issues driving my research. Through funding by the Yale Center for Environmental Law and Policy and pilot support from the Yale Institute of Biospheric Studies, I am collaborating with the Nexus Alliance of small-scale project developers to trace benefit flows and to identify principles for success when designing pro-poor cookstove and kitchen interventions.
Jasmine Hyman, M.Sc. (LSE), B.A. (Columbia) is completing a doctorate at the Yale School of Forestry & Environmental Studies, where she holds a doctoral fellowship from the National Science Foundation. Her research seeks to identify design principles for global climate finance schemes that promote equitable development and social justice.
 Kosa, Chea and Mara, Yos (2006), "Children's Empowerment through Education Services (CHES) Project in Siem Reap Province," in Winrock International (ed.), (Phnom Penh).
 Doherty, Ben (2010), "Angkor Butterfly Hunters Tell of Poverty Amid Tourist Wealth," The Guardian.
 Names have been changed.
 van Mansvelt, Rogier (2011) "Biodigester User Survey 2009-2011," for NBP, Phnom Penh
 Capoor, Karan and Ambrosi, Philippe (2010), "State and Trends of the Carbon Market 2010," (Washington DC: The World Bank).
 UNEP RISOE, CDM in Charts, Accessed July 2011.