Wednesday, July 28, 2010

How do we use 99 quadrillion Btu's of energy?

The US consumed over 99 Quads of energy in 2008. Where did it go? Over 57 Quads were unused, leaving less than half of the total to be useful energy.

The National Academies have posted an interactive diagram of energy systems as part of a feature on What You Need to Know about Energy. The flow diagram is based on work done at Lawrence Livermore National Lab.

The Academies says that for this analysis,
Hydro, wind, and solar electricity inputs are expressed using fossil-fuel plants’ heat rate to more easily account for differences between the conversion efficiency of renewables and the fuel utilization for combustion- and nuclear-driven systems. This enables hydro, wind, and solar to be counted on a similar basis as coal, natural gas, and oil. For this reason, the sum of the inputs for electricity differs slightly from the displayed total electricity output. Distributed electricity represents only retail electricity sales and does not include self-generation. The efficiency of electricity production is calculated as the total retail electricity delivered divided by the primary energy input into electricity generation. End use efficiency is estimated as 80% for residential, commercial, and industrial sectors, and as 25% for the transportation sector. Totals may not equal the sum of components due to independent rounding.

Presentations like this are crucial to rational discussions of energy policy in this country. There is widespread misunderstanding of where our energy comes from, with large parts of the public believing that renewable energy supplies vastly greater amounts of energy than it does and with little recognition of how most of our electricity is generated.

And think about the impacts of not producing the 57 Quads of energy that were not useful - on the economy, on business, the environment, on our checkbooks.

thanks to Sheril Kirstenbaum who blogs at Discovery Magazine's The Intersection, for spotting this.

No comments:

Post a Comment