10/04/2013 - 10:39

Think small

In his Round One essay, José R. Moreira focused on biofuels' potential to meet the need for transportation fuel while also mitigating climate change. He provided a largely positive view of biofuels, not surprising in light of the prominence that biofuels have assumed in his nation of Brazil. Roberto Bissio discussed the potential adverse impacts of bioenergy projects on forests and agricultural lands, while also devoting attention to developed countries' responsibility to reduce their carbon dioxide emissions. My colleagues maintain starkly different views, but they have one thing in common so far: large-scale bioenergy projects. I would argue that small-scale projects—because of their potential to mitigate climate change and support sustainable rural development, without undermining food security or incurring unmanageable expense—deserve a great deal of attention.

The International Energy Agency estimates that 2.7 billion people worldwide lack access to clean cooking facilities and that 1.3 billion people lack access to electricity. Most people who suffer from energy poverty—84 percent—live in rural areas. Bioenergy, the agency argues, can play a significant role in achieving global access to clean energy, notably among the rural poor. An array of modern, small-scale technologies can contribute to this effort. These include efficient cookstoves, biogas for cooking and village electrification, biomass gasifiers, and decentralized cogeneration systems that utilize bagasse (the fiber that remains after liquid is extracted from sugarcane). These biomass-based options, partly by reducing the carbon dioxide emissions that result from unsustainable biomass harvesting, could achieve a 1-gigaton reduction in annual greenhouse gas emissions. They could also reduce, by 60 to 90 percent, emissions of black carbon—essentially, soot—which is blamed for 2 million deaths each year.

A detailed World Bank study of Mexico covering the period 2009 to 2030 determined that adoption of advanced biomass stoves could, while producing a net economic benefit, reduce carbon dioxide emissions by 19.4 megatons a year—a larger reduction than could be achieved by any other action in the residential sector. A study in India, meanwhile, compared the mitigation potential of decentralized bioenergy for village electrification with the mitigation potential of carbon sequestration through forestry. The study concluded that, over 100 years, substituting biomass energy for diesel fuel would prevent 92.5 tons of carbon per hectare from entering the atmosphere. The forestry projects would achieve less. Long-rotation projects would keep 45.2 metric tons of carbon per hectare out of the atmosphere, while short-rotation projects would keep only 23.9 tons per hectare out of the atmosphere.

Decentralized applications of small-scale, modern bioenergy options—particularly in rural parts of developing countries—generally represent win-win approaches. They can provide benefits along the climatic, environmental, and social dimensions while avoiding adverse effects on food security. In discussions of biomass energy, it is important to avoid excessive focus on the large-scale production of biofuels for transportation. Other approaches exist—approaches that can mitigate climate change while presenting only minimal implications for the environment and food production.