Categorized | Renewable energy, Solar power

Solar thermal may have future combined with photovoltaic

Solar Thermal, also known as Concentrating Solar Power, could have a future when combined with solar photovoltaic power.

Photovoltaic power is cheap and getting cheaper but has highly variable power generation. CSP, in which power is created by focusing the heat of the sun to a central tower to power turbines, has a huge advantage because it can store heat in molten salt to power turbines at night. But CSP also has a huge drawback. It requires water, lots of it, and in the middle of deserts too. There are ways to lessen water use but they raises the price of the power thus at least partially defeating the purpose of CSP.

Tom Konrad at Forbes details how PV and CSP could co-exist together, theoretically at least providing steady power. Big PV installations alone could destabliize the grid but combined with the stored power of CSP might work in places like Saudi Arabia.

This might make sense for large scale solar farms, since the integration of PV would allow the overall price of power to be lower than CSP alone, while CSP would be able to compensate for the rapid output changes from PV that occur whenever a cloud passes over, as well as producing power at night, or shifting it at peak afternoon periods.

I’m still skeptical of CSP. Slurping up huge amounts of water in deserts is not sustainable or a good idea especially if it starts happening on grid scale. All that water has to come from somewhere and deserts by definition already don’t have enough water.

It’s a bit of a vicious cycle isn’t it? Coal, nuclear, natural gas, and CSP require large amounts of water while pumping water is a major use of electricity in dry areas. The current bottleneck, as always, in the grid. It wan’t designed to handle fluctuating power from multiple sources. CSP is unique in that it can store heat to be used to generate energy at a later time. The only way PV can store power would be through grid scale sized batteries, and that technology doesn’t really exist yet at an affordable price.


Bob Morris


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