Just like it is in managing an investment portfolio, diversity is key to planning a smart, balanced energy resource portfolio. Resource diversity helps mitigate risks and helps ensure a reliable, reasonably priced energy supply.
Natural gas is the cleanest and most efficient of the fossil fuels. The technology for producing electricity from natural gas plants can be used for a variety of different applications. While natural gas fired power plants do emit greenhouse gases, the amount is typically one-half to one-third as much as coal.
Natural gas cogeneration generates electricity from the heat created by burning natural gas for another process, such as industrial heating or manufacturing.
Coal is the most abundant and least expensive fuel source for energy in the nation. It’s also a reliable source of energy. However, coal production also happens to be very high in greenhouse gases and other polluting emissions.
Presently SDG&E has only one contract for energy that comes from coal, and it accounts for just 3% of our overall energy supplies. The contract will sunset in 2013, at which time we will have no direct coal-sourced supplies.
Nuclear-generated electricity is typically used for everyday-use energy. It's an emissions-free energy source that produces virtually no greenhouse gases as it's not a fossil fuel. The energy created by nuclear power is captured from splitting atoms, which requires very strict safety controls. The biggest concern with nuclear power is spent fuel storage and the environmental/safety concerns that the spent fuel may cause. In 2008, we got 16% of our energy from nuclear generation.