Baseload power is the part of the electric supply that has to be available all the time, day in and day out.
Traditionally, baseload power was supplied by big power plants that ran continuously. These plants included hydro, coal, and nuclear. They could be counted on as a power source, and if demand increased, they could often cover that demand by increasing output. Natural gas plants, by contrast, could often economically be allowed to sit idle, and be fired up when demand became great.
Many proponents of traditional technology, such as coal and nuclear, object to renewable power sources because they are not considered baseload providers. The objections are themselves founded in obsolete technical considerations. Today, the idea of baseload power requiring a small number of large power stations running around the clock has become archaic. Technology has passed it by. Reductions in transmission line loss and grid power storage facilities are two examples of how this happened.
Transmission line loss
When nuclear power plants were first being contemplated, in the 1950s, they were designed by a fresh group of engineers in a new tradition. These engineers may have been on the cutting edge of their own technology, but they were not at the cutting edge of transmission technology, so they used an understanding of transmission lines that dated from the 1940s or 1930s. The result is that nuclear power plants were sited close to cities to reduce line loss, usually within fifty miles.
The conventional wisdom of the time said that electricity could not be transmitted very far economically because of transmission line loss. By 1980, however, the line loss was down to 8.9%, and the US Department of Energy was using figures for economically feasible transmission of power of 4000 kilometers (2500 miles) for AC and 7000 kilometers (4300 miles) for high voltage DC. Today, the line loss for current transmission technologies has been reduced below 6.5%, and for cutting edge technology it has been reduced to below 2.5%. This means that is economically possible to generate power anywhere in North America for transmission to anywhere in North America.
The US has a huge wind potential. The Midwest alone has a wind potential that is a multiple of US demand, and even exceeds world demand. If the wind is calm in the entire State of Texas, it will be blowing somewhere in the Dakotas, Iowa, Montana, or the other states in the center of the nation. This represents only part of the wind potential of the country, however, and does not consider other renewable resources.
When the nuclear plants were first being built, there were no large-scale electrical storage facilities. We had batteries for small-scale storage, even up to the size of those in submarines. But the idea of storing electrical power to be put on the grid was not being considered much.
Today, things are different. There are a number of storage systems that can be put into use. The most important of these, for putting electricity on the grid, is pumped storage. While an excess supply of electricity is available, water is pumped from a low reservoir or a river to a high reservoir on a mountain top. When demand increases, the water is used to generate power.
Historically, the water was typically put on the mountain top when nighttime demand was low, and used for power in the daytime. With an increase in the use of renewable power, the supply and demand schedule is a little less predictable, but it does mean that whenever there is an excess supply of electricity, it can be stored for use when the demand is higher.
The output of pumped storage facilities in Germany is about 7 gigawatts. This is roughly equivalent to seven nuclear power plants. The storage is about 40 gigawatt hours, which is about 5% of a day’s power demand. Similar systems are used elsewhere.