Intermittency Need Not Be a Problem

There is no question that the future of power will be from the sun. Wind generation and solar panels are the predominant contenders. The president has wrongheadedly bragged about bringing back coal as an energy source. It hasn’t nor will it happen for simple economic reasons. Natural gas generation of electricity is cheaper and wind and solar are rapidly approaching parity in cost. Burning coal has the additional unaccounted burden of fouling our air and water.

The only advantage that fossil fuels have is that once extracted, they are available for power production near continuously. Sustainable sources such as wind and solar are available only intermittently. The relative availability is referred to capacity factor (CF), the fraction of time when a power source is available. Generally fossil fuel consuming power sources have higher capacity factors than intermittent sustainable sources, but are by no means constant.

The point of this is that all our electric generation sources are intermittent to a degree but power demands are continuous. At times less power is needed such as at night, or during the spring and fall when less heating or cooling is needed. Interconnected grid systems match power production and demand by balancing the various sources. Sustainability experts estimate that we can introduce intermittent power sources into the gird up to about 30 % of our total production without changing anything. After that we will need to add storage or change the way we utilize available intermittent power production.

Most think of batteries when considering electricity storage, but it is not the electricity necessarily that needs to be stored but rather the potential. Pumped storage is an example of the latter. In several locations, excess power at night can be used to pump water up a hill into a storage reservoir. During the day when demand increases water can be released to generate power.

Another strategy is to match jobs and/or lifestyle to the availability of electrical power just like we do for other traditional activities. We don’t grow corn and beans in the winter. We don’t go downhill skiing in the summer. In some locales power consumption is managed on a small scale with time of day pricing of electricity. Generally there is less demand for electricity at night, so power companies lower the price at night. This influences people to shift power consuming activities to later hours.

Larger scale operations could be shifted to times when energy is more available. The upper midwest has abundant wind energy available. It is available intermittently but predictably. Manufacturing schedules could be matched with the availability of lower cost power.

Solar power could easily be matched with power needs which themselves are only intermittent. Huckleberry Creek north of Russellville, Arkansas is a 500 acre man-made impoundment. It provides drinking water and in most years is sufficient. On occasion water is pumped from the Illinois Bayou uphill into the impoundment. Pontoon mounted solar panels could be floated on the lake to provide pumping power. There are a couple additional advantages here. Evaporation would be reduced by panel coverage and the solar panels themselves would be more efficient due to cooling from the water.

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