Buildings and Cities
Over the course of a century, methane has 34 times the greenhouse effect of carbon dioxide. Landfills are a top source of methane emissions, releasing 12 percent of the world’s total. Landfill methane can be tapped, captured, and used as a fairly clean energy source for generating electricity or heat, rather than leaking into the air or being dispersed as waste. The climate benefit is twofold: prevent landfill emissions and displace coal, oil, or natural gas that might otherwise be used.
Most landfill content is organic matter: food scraps, yard trimmings, junk wood, wastepaper. Their decomposition produces biogas, a roughly equal blend of carbon dioxide and methane accompanied by a smattering of other gases. Ideally, those wastes would be recycled, composted, or digested. But as long as landfills are piling up, we must manage the methane coming out of them.
The technology to manage biogas is relatively simple. Dispersed, perforated tubes are sent down into a landfill’s depths to collect gas, which is piped to a central collection area where it can be vented or flared. Better still, it can be compressed and purified for use as fuel in generators, garbage trucks, or mixed into natural gas supply.
Methane [vs.] carbon dioxide: Myhre, Gunnar, Drew Shindell, François-Marie Bréon, William Collins, Jan Fuglestvedt, Jianping Huang, Dorothy Koch et al. “Anthropogenic and natural radiative forcing.” In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2013.
Landfills…methane emissions: Bogner, J., et al. “Waste Management.” In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2007.
Landfill methane…energy source: EPA. Solid Waste Management and Greenhouse Gases—A Life-Cycle Assessment of Emission and Sinks. 3rd edition. Washington, D.C.: U.S. Environmental Protection Agency, 2006.
cities…[volumes of] solid waste: Hoornweg, Daniel, and Perinaz Bhada-Tata. What a Waste: A Global Review of Solid Waste Management. Washington, D.C.: The World Bank, 2012.
sustainable waste-diversion approaches: Laurent, A., et al. “Review of LCA Studies of Solid Waste Management Systems—Part I: Lessons Learned and Perspectives.” Waste Management 34, no. 3 (2014): 573–588.
open landfills…methane emissions: Powell, Jon T., Timothy G. Townsend, and Julie B. Zimmerman. “Estimates of Solid Waste Disposal Rates and Reduction Targets for Landfill Gas Emissions.” Nature Climate Change 6 (2016): 162–165.