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CANBERRA – Ask any power system engineer about renewable energy and you are likely to be told that it doesn’t deliver “base-load” power. In other words, renewable energy can’t be relied upon to provide power 24 hours a day, seven days a week: wind doesn’t always spin the turbines on the hill, the sun cannot shine on solar power stations at night, and even hydroelectricity can run short if the rains don’t come.

The inherently erratic behavior of the major renewable energy technologies presents serious problems for power system planners. It limits how much of these types of renewable power can usefully be fed into the world’s electricity grids. After all, consumers expect power always to be available.

The engineering solution is to keep a large amount of reliable base-load power as a major component of the generating mix and supplement this with “peaking plants” that can be brought on-line when needs arise. This peaking capacity is built around hydroelectric systems in some countries, but usually it is based on burning fossil fuels such as gas, diesel, or fuel oils.

The base-load power, too, is predominantly based on fossil fuels, with around 39% of global electricity generation sourced from burning coal. In some countries, nuclear power has been seen as an answer, but deposits of high-grade nuclear fuel worldwide appear to be limited, and the long-term costs of waste storage and plant decommissioning are high.