From Envirowiki

Pretty much all sources of electricity require some sort of energy input before energy can be paid back, dams need to be built for hydro, silicon panels for photovoltaics, power plants for coal and nuclear, pumps for geothermal etc.

This page lists the relative energy cost, how long it takes (on average, with current technology) to pay them back, and what ratio of energy input to energy gain on gets over the life cycle of the plant.

Note: this page so far ignores external effects, such as greenhouse pollution, or nuclear waste.

[edit] 1 life cycle payback

World Energy Council, 2004^[1]

Energy source type	country	output (MW)	Load factor	Lifespan (years)	Payback ratio
Coal	USA	1000	75%	40	11
	USA, low-NOx	524	60 %	30	5,1
	USA, CuO	425	60 %	30	6,7
Natural gas combined cycle	USA, SCR	505	80 %	30	2,2
	Cass County	620	75 %	40	4,1
Wind power	USA	0,34	24 %	30	14,4
	USA	0,75	35 %	25	8,9
	USA	0,6	31 %	20	20
Solar photovoltaic	USA	0,008	(not given)	30	5,7
Nuclear	USA	1000	75 %	40	16

(higher ratio is better in terms of embodied energy vs. energy gain, though perhaps not in pollution)

[edit] 2 References

1. ↑ Comparison of Energy Systems Using Life Cycle Asessment, A Special Report of the World Energy Council July 2004, Table 6.7, Page 48.