Energy Return on Investment (EROI) For Wind Energy (Oil Drum)

[jpak]

http://www.theoildrum.com/story/2006/10/17/18478/085

Wind energy is one of the fastest growing energy systems in the world. In Europe and the United States, wind-powered generating capacity increased by 18 percent and 27 percent, respectively, in 2005 alone. While the rate of increase is impressive, wind still accounts for less than one percent of the world's electricity generation.

The surge in wind energy is due to a combination of factors, including reduction in the cost of wind turbines, volatile prices for conventional forms of energy, the demand for non-carbon forms of energy to mitigate the effects of climate change, and generous government subsidies such as feed-in tariffs in Europe and the production tax credit in the United States.

One technique for evaluating energy systems is net energy analysis, which seeks to compare the amount of energy delivered to society by a technology to the total energy required to find, extract, process, deliver, and otherwise upgrade that energy to a socially useful form. Energy return on investment (EROI) is the ratio of energy delivered to energy costs. In the case of electricity generation, the EROI entails the comparison of the electricity generated to the amount of primary energy used in the manufacture, transport, construction, operation, decommissioning, and other stages of the facility's life cycle (Figure 1).

Comparing cumulative energy requirements with the amount of electricity the technology produces over its lifetime yields a simple ratio for energy return on investment (EROI):

EROI = (cumulative electricity generated) / (cumulative primary energy required)

This article reviews 112 wind turbines from 41 different analyses, ranging in publication date from 1977 to 2006. This survey shows average EROI for all studies (operational and conceptual) of 24.6 (n=109; std. dev=22.3). The average EROI for just the operational studies is 18.1 (n=158; std. dev=13.7). This places wind energy in a favorable position relative to conventional power generation technologies in terms of EROI.

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[phantom power]

1. I wonder if those are poisson distributions. Or log-normal?

EROI can't go negative, but the "signal to noise" on those stats is not much larger than 1.0