The rapid advances in the use of solar and wind energy – more in Europe, but now also gaining momentum in the U.S.- has put electricity “storage” front and center. That is because there is no solar production at night and little on cloudy days, while strong winds are unpredictable in most locations. So, the best “model” for these renewable energy sources is to generate as much as possible at favorable times and to “store” excess production for periods when solar and wind energy supply are low.
And the cost of solar power is declining amazingly. Austin Energy signed a deal recently that a solar farm is selling at 5 cents a kilowatt-hour. A recent study by Lazard gave a cost of 5.6 cents for solar and 1.4 cents for wind power (with current subsidies) or 7.2 cents for solar and 3.7 cents for wind without subsidies. Natural gas came in at 6.1 cents and coal at 6.6 cents. The Solar Energy Industries Association claims that in the Southwest electricity contracts for solar energy have dropped 70 percent since 2008.
American Electric Power, the country’s largest utility, recently tripled the amount of wind power it contracts in Oklahoma.
It has been projected that world electric energy storage will rise from the current 1.2 gigawatts to 11.3 gigawatts by 2020. California has mandated utilities to add storage and Germany has budgeted 200 million Euros for various types of energy storage pilot plants.
Electricity storage in this context can be carried out using pumped water storage, compressed air and production of hydrogen and oxygen via electrolysis, the latter when combined with carbon dioxide can produce synthetic natural gas, which fuels conventional power plants. Trimet Aluminium, Germany’s largest aluminum producer located in the Ruhr region, is planning to store huge amounts of electricity as an adjunct to aluminum manufacture. This process, which converts bauxite ore to the shiny metal is extremely power-intensive with the electrolysis of aluminum oxide to the metal in huge cells. The process can be reversed by reacting the molten metal with oxygen forming a sort of battery that can take power from the grid when electricity is cheap (e.g. at night) and putting power back into the grid when power demand peaks. The company estimates that it should be able to store enough power to meet the needs of 300,000 homes during a peak period.
Switching from “macro” to “micro” there is now a move to make solar panels in domestic residences face west instead of south(!). Home electricity demand is low in the middle of the day and high in the afternoon and early evening. Beginning at 5PM, solar panels average 55% of peak output, but when pointing south they produce only 15% of peak as demand is then low.