Building Integrated Hydro Power

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A reader asks:

My question is, can you develop any significant electrical power by diverting roof rain water down narrow riser pipes through mini-turbines? I have seen some mini-turbines on websites (advancedpower, etc.), so it seems that there is potential, but you would probably have a better knowledge of this.

An additional question would be, can fuel cells be used to store the energy that these turbines produce (sort of like an elec car battery)? It seems that all the fuel cells coming to the market today are energy producing, and not storage related.

Last question is, a lot of energy and space in hi-rise building is dedicated to elevators. Although the energy to provide up-lift may not be able to be reduced, I am wondering if energy can be obtained from the car lowering (again, stored in a fuel cell/ battery)?

-- chris schaffner (chris@greenengineer.com), October 01, 2003

Answers

Question 1 - I don't see why this wouldn't work, in principal. I doubt the economics are good, as you'd only generate power in the rain. I think typically you would need a steady source of flow (like a stream) to make this work.

Question 2 - Fuel Cells are not like rechargable batteries - they generate electricity in a one way chemical reaction. Commercially available fuel cells run on natural gas, so unless you've got a way to make natural gas, you wont be able to use these as a storage device. A better bet would be to capture the potential energy of the water, by storing at the top of the building, until you need the power. That being said, I doubt that youd ever need to store the energy from your rain-hydro system - probably the power available doesn't cover the base load.

Question 3 - Elevators are usually counterbalanced, so the energy for uplift and descent are roughly equal, and are limited to overcoming the friction in the system. There's no source of energy there. Of course, I suppose high speed elevators could use regenerative braking, to capture the kinetic energy as the car stops, a la hybrid cars.

-- chris schaffner (chris@greenengineer.com), October 01, 2003.


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