Base load electricity, as defined by Open Energy Information is “The minimum amount of electric power delivered or required over a given period at a constant rate” (This statement is from North American Electric Reliability Corporation (NERC) glossary of terms). Open Energy Information also adds “Base load requirement (also baseload) is the minimum level of demand on an electrical supply system over 24 hours. Base load power sources are those plants which can generate dependable power to consistently meet demand. They are the foundation of a sound electrical system.” Electricity grid operators of course recognize the importance of base load electricity generation, for example, search “baseload” here, a glossary via New England Independent System Operator. A straightforward explanation of base load, along with peak load, generation is explained here. Base load (and other electricity grid operation terms) is also clearly defined here.
We have seen base load electricity described by National Resources Defense Council “The idea of baseload itself is obsolete.” . It has also been described as a “myth” and “a myth used to defend the fossil fuel industry“. Michael Liebreich, founder of Bloomberg New Energy Finance, has referred to it as “so 20th C(entury)!”
Some examples of systems or appliances that require reliable, around-the-clock, on-demand electricity are hospitals, refrigerators, water pumping and purification, sewage treatment, street lights, electric fans in furnaces, air conditioning, Internet, computer data centres, police and fire departments, air traffic control, 7x24x365 industry, animal farms etc.
Generally speaking, modern societies use the least amount of electricity at about 3am and the most when arriving home from work and/or school (exception would be another usage peak in summer for air conditioning in mid afternoon). How much electricity is used at this minimum time (and maximum time)? You can see that for Ontario Canada here, Midcontinent Independent System Operator here New England USA here Texas USA here and California USA here.
What will supply the electricity at this minimum usage time? Some of these (fossil fuels, nuclear, hydro) are described here.
If intermittent renewable energy is to play a role in supplying electricity at this minimum usage time, then storage is critical. Far and away, pumped hydro storage is the dominant form of electricity storage today (approximately 97%), as per the International Energy Agency. Scotland closed its largest coal plant March 2016 and this will present challenges for grid stability. Pumped hydro storage could assist, but its limitations (for example, hilly terrain) are described for the UK grid here. It is unclear to me how much electricity is supplied globally by storage, but it is not even mentioned here, so I would speculate well under 1%. A detailed examination of electricity storage is here. The International Energy Agency wrote a short post regarding storage.
In summary, as global population grows, struggles to climb out of poverty, becomes more urbanized and lives more densely, it is my opinion that base load electricity generation sources will be critical to modern societies for the foreseeable future.
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