K. de Groot & C. le Pair
(Former Shell & STW, The Netherlands.)
Wind generated electricity requires back-up capacity of conventional power stations. This capacity is required to deliver electricity to consumers when wind supply is falling short. To have the non-wind power stations ramp up or down to compensate for the stochastic wind variations causes extra efficiency loss for such power stations. How much efficiency is lost in this way and how much extra fuel is required for this extra balancing of supply and demand is unknown. In this article we attempt to make an educated guess.
The extra fuel required for the efficiency loss must be added to the fuel required for building and installing the wind turbines and the additions to the power cable network. While these extra requirements may be too small to notice when the installed wind power is a small fraction of the total capacity, matters change when wind capacity becomes significant. Based on the German situation with 23 GW of installed wind power, we show that it becomes doubtful whether wind energy results in any fuel saving and CO2 emission reduction. What remains are the extra investments in wind energy.
Wind energy comes for free, but it does not follow that electricity generation using wind is also free. The hardware costs money and energy to build. The energy required for this is typically derived from fossil sources. More importantly, one needs to maintain a conventional back-up power generator capacity roughly equal to the installed wind power capacity.
The wind may be free of charge, but it is not provided in the desired doses. Wind varies. The variations do not match the electricity demand. Because there is as yet no economically viable method to store electricity, the variations in wind generated electricity levels that do not match demand levels have to be met by adjusting the output of conventional power stations. In his recent thesis1 Ummels concludes on the basis of computer modelling studies that such adjustments can be made “without problems” even when wind would generate electricity equivalent to 33% of the Dutch demand.
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