Climate Change and Forests: Emerging Policy and Market Opportunities

Chapter 7. How Renewable Is Bioenergy?

At forty-six exajoules per year, bioenergy constitutes more than 10 percent of global primary energy. Traditional solid biomass fuels (fuelwood, charcoal, dung, and straw) constitute about 80 percent of global biomass use. Lately interest in biofuels and bioenergy has increased significantly as a result of higher fossil fuel prices, concerns about energy security, and the need to reduce greenhouse gas (GHG) emissions to mitigate climate change. The drive to increase bioenergy consumption is raising concerns among nongovernmental organizations (NGOs) and in both the mainstream and the alternative press.1 These concerns are not only that increased use of bioenergy will produce no net benefit for climate mitigation but also that it will negatively affect biodiversity, water, and food security.2 In this chapter we address the question, Under what conditions can biomass energy be seen as CO2 neutral or renewable? We pay special attention to tradeoffs and synergies with carbon sequestration on agricultural and forestry land. We discuss the relevance of emissions associated with the production and use of biomass , indirect effects through agricultural markets, and bioenergy’s role in the Kyoto Protocol and especially in the Clean Development Mechanism (CDM). The Greenhouse Gas Benefits of Bioenergy The main interest in bioenergy as a climate change mitigation strategy is that it is a CO2 neutral energy source, provided that the bioenergy is sustainably produced— How Renewable Is Bioenergy? bernhard schlamadinger, sandra greiner, scott settelmyer, and david neil bird 7 89 that is, it comes from a renewable biomass source. This view is based on the premise that the same amount of CO2 is released at the point of use as is removed from the atmosphere via photosynthesis (figure 7-1). In countries with national GHG emission targets under the Kyoto Protocol (Annex I countries), it is assumed that sustainable agricultural and forestry practices are in effect and that if they are not, then any loss of biomass, particularly through deforestation, is captured in the land-use part of the national GHG inventory. For countries without national GHG emission targets (non–Annex I countries ), no assumption of sustainable agricultural and forestry practice is made, and the renewability of the biomass for energy use must be demonstrated. This has been a significant stumbling block for acceptance of methodologies for biofuel projects under the CDM. Net CO2 emissions from the use of biomass can be ignored only if biomass is renewable.3 Woody and nonwoody biomass is defined as renewable under the CDM if (1) there is no change in land use or the landuse change is from cropland or grassland to forest (that is, afforestation or reforestation ), (2) sustainable management practices are in effect to ensure that there is no systematic decrease in carbon stocks on the land, and (3) the practice is in 90 b. schlamadinger, s. greiner, s. settelmyer, and d. n. bird Figure 7-1. Closed Carbon Cycle Associated with Biomass Use for Energy CO2 released by burning biomass matches uptake by crop and forest growth CO2 EMISSIONS FROM FOSSIL FUEL RESERVES ZERO BALANCE ZERO CO2 SEQUESTERED ZERO Source: IEA Bioenergy Task 38, Greenhouse Gas Balances of Biomass and Bioenergy Systems, “Answers to ten frequently asked questions about bioenergy, carbon sinks and their role in global climate change” (www.ieabioenergy-task38.org/publications/faq/). Figure compiled by R. Matthews. compliance with all national and regional forestry, agriculture, and environmental regulations.4 Residual biomass from agricultural or forestry operations is also considered renewable if use of the residues does not cause a decrease in carbon stocks on the land where the biomass originated. In practice, biomass energy is not always from renewable sources. Land management associated with production of biomass may result in decreases of carbon stocks in the five relevant carbon pools: above-ground biomass, below-ground biomass, deadwood, litter, and soil. For example, the production of biofuels from palm oil plantations is not renewable if the land was deforested to establish the palm oil plantation. Similarly, retrieving biomass may result in the decrease of deadwood, litter, or soil carbon stocks. A project that increases the collection of deadwood in an existing forest, for example, would not be considered renewable if this practice depletes the pool of deadwood in the forest. Another example is the planting of an annually tilled bioenergy crop such as rapeseed on grassland. The tillage of the soil could cause a systematic decrease in soil carbon stocks, so...