Two global problems
Energy can be defined as the capacity of a system to perform work. There appear to be two main global problems in relation to providing energy to modern industrial and commercial systems so that work can be performed.
The first problem relates to the production of greenhouse gases. To date, most systems such as those involved in electricity generation, require large amounts of fossil fuels. The combustion of fossil fuels such as natural gas and coal produces carbon dioxide emissions. Many in the community consider carbon dioxide to be a major greenhouse gas associated with climate change and actively campaign against the use of fossil fuels for the production of energy, particularly the production of electricity.
The second problem relates to energy storage when the energy is derived from renewable sources such as solar, wind, hydro, etc. The production of electricity from renewable sources of energy is considered by many to be the ideal model to decrease national and international greenhouse gas emissions. However, renewable energy is inherently variable. As renewable energy becomes a considerable new source of energy for electricity generation, the variability of renewable energy will require new approaches in electricity generation, transmission and market systems. The problem becomes a problem of flexibility in capacity rather than just capacity per se.
It is considered that one method of stabilizing the variability of renewable energy is to store energy during periods of high availability (strong sunlight, high wind, etc.). This stored energy can then be released during periods when renewable energy is not available (lack of sunlight, lack of wind, etc.).