Recent legislative proposals in a number of states across the country have reignited the debate over how  ‘sustainable’ hydropower actually is,  and if it is truly emissions free. California’s Assembly Bill 1771, which was rejected in the state legislature this past April, would have allowed large hydropower facilities to contribute toward state Renewable Portfolio Standards (RPS). As a growing number of states establish increasingly ambitious targets for shares of energy production from renewable sources, there has been ongoing discussion about what types of hydropower should be included in these RPS schemes.

In the United States, state regulators divide hydro into two categories – small and large – depending on the facility’s installed generating capacity. For example, California considers any facility with at least 30 megawatts (MW) of capacity to be ‘large hydro’. Currently, utilities in most states can count only ‘small hydro’ toward RPS targets.

Zipingpu Dam in China's Sichuan Province

California’s Assembly Bill 1771 is neither the first nor the only proposal of its kind. As states that have implemented RPS programs scramble to reach their renewable energy targets, the movement to count large hydro towards these goals has gained momentum.  Similar bills have been proposed in California in the past, as well as in Minnesota. North Dakota currently counts all hydropower in its RPS, including power imported from Manitoba, but stipulates that large hydro facilities must have been placed in service on or after Dec. 31, 2010. Wisconsin will allow utilities to count hydropower from large facilities starting in 2015. 

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carbon sinks, hydropower, large hydro, low-carbon, renewable energy, renewables, small hydro, sustainability