Two new solar power technologies being funded by ARPA-E

oilprice.com
27 Feb 2013

The Solar Vortex is an idea being researched by a consortium led by Georgia Tech, which hopes to imitate the process that creates small twisters in order to drive a turbine.

A twister is created due to the temperature difference between the hot ground, and the cooler air above. The ground heats low level air, which then rises and begins to twist as the cool air above falls around the outside of the twisting column of hot air.

The consortium has created a short cylinder which sits on a dark surface which can absorb and emit a lot of heat. The air is warmed and caused to twist into a vortex by the angled walls. At the top of the cylinder is a fan attached to a generator which is turned by the rotating column of air, creating electricity.

Arne Pearlstein, a professor of mechanical engineering and part of the team working on the Solar Vortex, estimates that the device will produce electricity for 20% cheaper than wind turbines, and 65% cheaper than solar PV panels. This is mainly due to the reduced maintenance costs. "You're talking about somebody getting up on a stepladder instead of going hundreds of meters up into a wind turbine to deal with a gearbox", she said. Another new technology which is being funded by the ARPA-E is the Sunfolding heliostat for concentrating solar plants.

Heliostats are normally large, expensive constructs which must be strong enough to withstand high winds, and sit on a complex tracking system which must be durable enough to operate for years in hot, dusty environments. The sunfolding heliostat is much smaller than normal, meaning that it doesn't need to worry about the wind, and the tracking system has been replaced with two simple air bladders that inflate or deflate to change the angle of the mirror.

By making heliostats cheaper concentrated solar power could soon begin to generate electricity for a cost that is competitive with coal and natural gas.