Monday, January 28, 2013

Why are solar and wind called intermittent energy sources?

Solar and wind energy industry are rapidly expanding on global level but there are still some major issues these industries will have to solve prior to becoming top energy sources in the world. One of these issues is no doubt the intermittency of solar and wind energy.

Why do solar and wind belong to intermittent energy sources? Wind energy and solar energy are both called intermittent energy sources because these sources may be uncontrollably variable or more intermittent in normal operational conditions compared to traditional fossil fuels (oil, natural gas and coal). It is a well known fact that wind does not blow constantly all the time, and also we all know that our sun doesn't shine at night. What this means is that these two sources cannot guarantee reliability of delivery 24-7 without the adequate energy storage solution.

Let us deal with few well known facts to get a better picture here. For starters, wind speeds are usually (quite) higher in the night than during daytime, and you probably also know that winds tend to blow much faster in the winter compared to the summer. To continue the story, sun as we all know does not shine at night, and sunlight is also much stronger in summer than in the winter. What can be concluded from these facts? The right conclusion would be that using wind power and solar power in tandem could ensure reliability in delivery, as these two renewable energy sources can complement each other very well, and thus their combination could help reduce the intermittency issue to the minimum.

Even if we do not combine these two energy sources together we can still significantly reduce intermittency issue by for instance dispersing either wind turbines or solar panels across the very large area. There are many energy experts who say that a well planed "dispersion system" can dramatically decrease the intermittency effect, and ensure so much needed reliability in delivering electricity by drawing power from different areas and thus result in reducing variations in electricity generation.

There has been plenty of talk about „renewable energy storage solutions“ but sadly science and technology still haven't come up with the solutions that would be both very efficient and in the same time commercially viable. However, there has been a decent number of very promising studies and with the big money being invested by many countries around the globe the further research is bound to make future renewable energy storage methods more cost-effective. The U.S. alone has already announced to award more than $200 million in grants for utility-scale energy storage projects.

The future technological solutions will likely be able to solve the intermittency issue of wind and solar energy. Once intermittency issue comes out of the way this should open the door for much improved cost-effectiveness of solar and wind, paving the way to a future clean energy society.