Most environmental politics descend into absolutism faster than a rainbow sorbet cone melts on an ozone alert day in August, so I had better defend the title of this post quickly.
I am referring specifically to a brief think piece grafted in between the music in 7/7/07’s mega-concert. This interlude featured a line worker at a coal mine asserting that the world needs less coal and more wind energy.
I agree, but the implication here is that wind energy can easily replace coal, or natural gas, or nuclear energy if only we would build enough turbines to do so.
At best wind farms will generate energy approximately one-third of the time. To “firm” that energy for regular use some other form of energy has to be there the other two-thirds of the time. Here is an elemental explanation: A utility has 100 MWs of wind energy in its portfolio. Predictive models indicate that the wind farm will not produce any electricity for hour 0800; therefore, the utility needs to garner that energy in some other way which will be either peakable thermal (coal, nuclear, gas) or hydro. For hour 0900 the 100 MWs of wind will be on line, so 100 MWs of thermal energy will not be necessary.
In other words, wind does not replace thermal energy, it displaces it. While this is worthwhile, it also means that wind energy is reliant (outside of the Northwest) on thermal energy. Most utilities have the thermal capacity to integrate some wind but as demand increases and the MWs of wind in its portfolio increases it will be necessary to actually build additional thermal power plants to keep the wind online. Yes, at a certain point more wind = more thermal energy.
This dichotomy is especially important on peak energy days in the summer. Heat and humidity, the languid still air that leads to high energy demand is, unfortunately, exactly the weather that does not lead to the wind blowing — that is one of the reasons it feels so damn hot. Since the most polluting of resources will be mecessary to meet this highest of peak energy demands this situation does offer a very direct and slogan-ready way for a concrned citizen to aid the environment: Turn Off Your Air Conditioner on the Hottest Day of the Year!