Solar power comes in all sorts of forms, and not just solar panels, flat plate/evacuated tube collectors and heat pumps.
A technology that was first floated at the beginning of the 20th century is now gaining renewed interest – solar updraft towers.
The only modern solar updraft tower prototype to be built was in Spain in the 1980’s and it performed incredibly well. Since then and up until now, the technology has been largely ignored due to perceived inefficiencies; but with energy prices ever increasing it’s now getting another look.
How a solar updraft tower works
The collector area needs to be between 500 m and 10 km in diameter, with a centrally located hollow tower anywhere from 100 m to 1 km in height. The collector consists of transparent sheeting installed a few feet off the ground.
When the sun hits the sheeting, it passes through to the ground which is heated. The air immediately above the ground increases in temperature and as it’s trapped beneath the membrane, it flows towards the point of least resistance – the tower.
Air then rushes up the tower and spins a turbine located at the base it. Even at night, due to the difference in ground and air temperature, the effect continues.
While setup costs (land and equipment) are high, operations and maintenance costs are very low as the system is simple, very reliable and any moving parts are easy to get to.
A boon for farmers?
An interesting side effect of how the tower system works is that captures evaporated ground water and its return back to the earth, rendering what was possibly unusable land into ground suitable for agricultural uses.
The system could also be used in tandem with other renewable energy technologies such as PV arrays.
It’s a fascinating concept – you can learn more about solar updraft towers here.
