[Editor’s Note: This story has been updated to reflected consumption patterns as detailed by the EIA.]
According to the U.S. Energy Information Administration, during the first quarter of this year a combination of nuclear outages related to plants shutting down for refueling and the start of the high water season for hydropower generation caused the shift in consumption. Seasonal variations in renewable energy, said the EIA, “are dominated by the annual cycle of water availability for hydroelectric power production. Hydropower constitutes a significant yet highly variable portion of total renewable energy consumption, accounting for 31% of renewable energy consumption in 2010.”
Joining this is a multi-year upward trend in renewable consumption driven by increasing consumption of biofuels and wind capacity additions. In the context of this study, renewable energy consumption is defined beyond electric power generation from hydro, wind, solar, and geothermal sources. Sources including biofuels for transportation (such as ethanol and biodiesel) and biomass (such as wood and wood wastes) for space heating and industrial steam production as well as for electric power generation are counted as renewable resources.
With regards to data from the EIA, the various modes of energy consumption are put into common units (British thermal units, or Btu) for comparison purposes, with the end result of information representing the amount of fossil fuel consumption that might be displaced by the renewable generation. It is believed this approach produces a value greater than the result of a simple kilowatthour-to-Btu conversion.
It should be noted as well, the EIA mentioned, that with regards to the electricity-only portion of primary energy data, other energy use such as transportation, heating, or industrial steam production is excluded. When this is the case, renewable electricity generation—a subset of renewable energy—remains slightly below nuclear generation.