Concentrating on solar power

This article is from our September 2015 Newsletter "Force of Nature".

When you take a close look, solar power can be kind of confusing, so concentrate! When we talk about solar power we are commonly talking about photovoltaic power (PV). A PV system directly converts the suns energy (radiation) into usable power (electricity). We see PV systems in all kinds of places and it has tremendous potential to help create distributed generation and stabilize the electrical grid. 

PV, though, isn't the only game in town. Some major solar projects use different variations of what is called "concentrated (or "concentrating") solar power" or CSP. Unlike a PV system CSP uses energy from the sun as light, converts it to heart and heats  a liquid (often water) which runs an engine, which produces electricity. To make matters confusing sometimes CSP is called "concentrated solar thermal." And to add frosting to the confusion cake there is yet another form of solar power called "concentrator photovoltaics" (CPV). CPV uses curved mirrors and lenses but also uses the photovaltaic system. We won't focus on CPV today. 

Instead we focus on focusing. CSP systems use different systems to focus (concentrate) light. The graphic above shows simple version of different options and there are versions of CSP in many parts of the world. See this article by the Solar Energy Industries Association for examples of each.

A new off grid system of CSP called STEM is drawing attention from countries that want to produce large amounts of energy off grid. The STEM system uses silica sand as heat storage (Force of Nature discussed this storage system in volume 8). 

While CSP can produce a lot of energy, it is similar to other large scale energy infrastructure projects. It requires a lot of upfront capital. It works most efficiently if it produces at least 100 MW. It requires a lot of land. It often requires access to water. It usually requires access to transmission lines. Like other solar projects, it requires low cloud cover. 

In the U.S over 1500 MW of CSP operate and the Obama administration just announced 100 million in solar research. Of that $100 million the Journal Star reported that  "$32 million will be used on 14 projects researching how to improve the performance and efficiency of concentrating solar power plants, such as Abengoa Solar’s Solana solar plant in Arizona, which uses mirrors to concentrate reflected sunlight on a central point and then stores that energy in molten salt."  Purdue University also got an advanced grant to research CSP technology. 

Not all the big money though is on CSP. Citing the falling prices in PV technology, in 2011 Google dropped the CSP program it has launched in 2007. New plants though are cropping up around the world. 

What about Canada? Just this year Canada got its first Concentrated Solar Power project (or as it is referred to sometimes Concentrated Solar Thermal). The video below shows you around, take a tour!