Renewable energy is not dependablePublished 10:32am Friday, April 26, 2013
Unlike other commodities, electricity cannot be stored economically so production must match consumption on a real-time basis.
Turbines only work when the wind blows and solar panels only work when the sun shines.
Within the energy grid there must be a balance between the load and generation, but because of the varying levels of electricity produced by renewable sources this balance is hard to maintain, and poses one of the biggest challenges to the power sector.
An intermittent energy source is any source of energy that is not continuously available due to some factor outside direct control. The intermittent source may be quite predictable but cannot be dispatched to meet the demand of a power system.
Intermittency inherently affects solar energy, as the production of electricity depends on the amount of light energy in a given location. Solar output varies throughout the day and through the seasons, and is affected by cloud cover. Solar does not produce power at night.
The inability to meet demand can result in a system failure where no one receives power.
Intermittency inherent in solar production may potentially result in large limitations to its value as a power source.
Wind-generated power is also a variable resource, and the amount of electricity produced depends on wind speeds, air density and turbine characteristics. If wind speed is too low, they will not be able to make electricity, and if it is too high the turbine will have to be shut down to avoid damage.
The Australian Coal Association says because of the intermittency of wind, the percentage of the installed Australian wind generation capacity that is actually available on the average is just 25 percent to 40 percent.
The inescapable physical fact is that wind and solar power are not continuously available. “Since intermittent renewables by definition cannot provide a reliable supply of electricity, they must be backed up by conventional fuel sources such as coal, gas, hydro or nuclear.”
As we consider how to best transition to a greener energy economy, we must move forward cautiously and recognize that such a transition will take years, if not decades. How can we expect to reinvent in a few years what took a hundred years to build?
Joseph P. Smith