|Effect of wavelength on relative photosynthesis|
Economic Analysis of Greenhouse Lighting.
Using electricity at night when demand is low to pump water uphill into hydroelectric dams is one way energy can be stored. The water pumped uphill into hydroelectric dams runs back down hill through turbines to generate extra electricity when demand is high.
When you stop and think about this approach what leaps out is that storing energy is not free:
- A hydroelectric storage dam is an expensive capital investment.
- The electric motors and pumps that use electricity to pump water uphill into the storage dam are expensive capital items.
- The hydroelectric turbines and electricity generators are just as complex and costly as gas-fired turbines and electricity generators.
- The poles and wire that distribute the electricity from the hydroelectric power stations cost the same to build and maintain as the ones that distribute electricity from coal and gas-fired power stations.
Reasons to store energy
Demand for energy changes enormously - from season to season, from night to day, and from one day to the next.
In the last century investment in the capacity to generate electricity and to distribute electricity was tailored to supply electricity sufficient for the highest level of demand that may occur on just one day of a year.
The prevailing meme came to be that the cost of this investment was to be met by electricity consumers no matter how many days power stations and capacity in the distribution network were idle because demand was below the maximum that had been projected.
When demand fell from one year to the next because electricity consumers adopted energy-saving technologies the unit price of electricity - in cents per kilowatt-hour - was increased so that the same revenue could be collected.
Reasons to not store energy
If generating electricity is free then the prevailing meme of the 20th century has outlived its usefulness. Coal and gas-fired power station incur significant fuel costs if they are operated at times when demand is low.
Solar panels, solar thermal power stations, wind turbines and ocean wave power stations have no fuel costs. They are the exact opposite to coal and gas-fired power stations. There is no economic reason to "switch off" solar panels and wind turbines when they generate more electricity than is required.
|CETO 5 (Perth Wave Energy Project) Power & Water Schematic|
Increasing the generation of renewable energy so that it will always exceed demand creates economies of scale in manufacturing solar panels and wind turbines. This lowers the cost of installing new generating capacity.
With essentially free electricity being available on all but one day of the year when demand is at its maximum, the new meme for the 21st century is quite different:
what are the most profitable and discretionary ways to use electricity?The options to be considered are those that can be "powered down" whenever demand for electricity falls. This is the reverse of the situation for coal and gas-fired power stations that are powered down to avoid fuel costs when demand for electricity falls.
Examples include factories to manufacture hydrogen by electrolysis for the fertiliser industry and greenhouses that use electric lighting to grow crops.