The Price of Energy Consumption - The Renaissance of Renewable Energy - page 221

Process EROI

Electricity from CSP 4-10

Electricity from wind 10-25

Electricity from geothermal 11

Heat from solar thermal (warm water) 30-50

Heat from solar thermal (space heating) 5-10

* Risk costs not taken into account.

Sources: Dale et al. ( 2011 ) , Hacatoglu et al. ( 2012 ), Inman ( 2013a ), Kubiszewski
et al. ( 2010 ) , Kümmel ( 2011 ) , Murphy and Hall ( 2010 ) , Raugei et al. ( 2012 ), Smil
( 2008 ).

Coal, at the point it is removed from the ground, has a high EROI, but this falls sharply
when it is burned to generate electricity, and further still if the carbon dioxide is captured
and stored. The EROI of nuclear energy depends a lot on the technology used. Older
reactors are far less efficient and require more highly enriched fuels. Moreover, the EROI
of nuclear power generally does not include the costs of decommissioning the plant, of
waste disposal over thousands of years, or the potential for accidents. Solar PV has a low
EROI mainly because silicon (at present the main material in commercial solar cells) is
highly energy-intensive to manufacture. As technology improves and greater economies of
scale develop, the EROI of solar PV is certain to increase. Indeed, this is true of all the
alternative technologies, while the EROI of fossil fuels is destined to continue falling (Dale
et al. 2011 ) .

The current energy economy requires that fuels have an EROI above five. Only hydro,
fossil fuels, and solar thermal are well above this benchmark. As easily accessible oil
reserves dwindle, the EROI of fossil fuels will decrease, and societies will spend more on
energy production. (Inman 2013a , 2013b ).
EROI does not take into account all the benefits and drawbacks of a fuel. It does not
consider the environmental costs or the quality of the source. Nevertheless, EROI offers a