Using water to produce wind to produce energy – what a waste of water!
I’ve been involved in a couple of buildings prior to Cundall where ‘shower towers‘ were used to generate airflow into a building through creating an evaporatively cooled downdraught (no fans), in principle they work but the practical reality of sticking them in building is a bit tricky. There is also the impact of using water in drought stricken areas to generate cooling when air conditioning can possibly do it in a more environmentally friendly way.
Now imagine trying to use the same technology to generate energy from wind turbines at the bottom of the tower.
This is exactly what is being proposed by a US firm Clean Wind Energy. Unfortunately I found this on treehugger.com, I’d hoped they would vet their coverage a bit more.
Now the article is titled “Using Solar Energy to Create Wind Power”, solar has nothing to do with the physical process that is happening within the tower but calling it “Using Water to Create Wind Power” would have sounded a bit daft!
The website doesn’t have any dimensions but it looks to be about 200m across, and has a stated velocity of 50mph at the bottom of the shaft. So assuming a 30degC 30%RH day, water is used to evaporatively cool the air so that it falls through buoyancy to the bottom of the tower. The air then forces its way through the turbines. 200m diameter and 50mph through the turbines gives a certain air volume, assuming the air would have increased to 80%RH due to the water added allows us to calculate how much water would be lost through evaporation. By my rough calculations this is the equivalent to an olympic size swimming pool of water lost every hour. Now this is water lost through evaporation, non of it can be recycled – one olympic sized pool of water every hour. No wonder it needs 17% of its 700 megawatt hours to pump water to the top of the tower.
So what would you rather do with the water – produce energy that could be produced more efficiently offshore or irrigate 200,000m2 of land to grow food for our growing population?