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Hydro Electric Power As a Viable Alternative?
Hi Linda,
I hate to dampen your entheusiasm, but there is not a lot of energy in the rainwater even from the top of the roof...
The potential energy is given by the equation Ep = MGH. So to light a 100W lightbulb you'd need 100J / second
we'll solve for water flow... M = Ep/GH
Ep = 100J/sec (where J = kg*m)
H = 10 meters or 30 ft (the peak of a 2 story colonial)
G = 9.8m/sec^2 (we'll say 10)
M = 1.02 kg/sec (~> 1 liter/second or 16.1 gal/min)
16 gal/min falling from the rooftop... that's a lot of water for just one 100W lightbulb! That's why dams are as tall as they are, and the pipes are tens of feet in diameter...
Now if you get a tiny little "grain of wheat" or even smaller "grain of rice" lightbulb, or an even more efficient LED, you can probably do a nice demonstration for the science fair. Or you can drive a "solar" electric motor...
Good luck with tyour project! It's great that you're teaching some of the real principles of energy at such a young age. :-) So many kids are completely ignorant to the reality... They've never hauled firewood, never seen a gas stove, barely see the heating elements in an electric, and the microwave is just a magic box with a pushbutton.
Excellent work! I am thrilled to see this kind of idea is being considered.
I too had the same idea and unfoutunately came to the same conclusion. This type of system is not feasible for residential applications.. HOWEVER.
I took this to the next step. I looked at skyscrapers. Given that you can double the energy for each each meter of height I thought that perhaps this could provide a decent ROI. Conclusion: Yes and No. Only in cases where the building has sufficient height, sufficient roof top collection area and is located in an area with sufficient rainfall. There are in fact many cities in the world with buildings that meet this criteria.
Further to that I began to ponder...where do we have existing infrastructure with a massive amount of surface collection area combined with significant height. (i.e. more than 15 meters)...the answer BRIDGES.
Bridges located in areas with high average annual rainfall already have the piping in place to vent rainfall from the road area into storm sewers or other bodies of water. Additionally they have the height required to make 15 meter or more drop to supply a multiple that can provide a decent ROI.
I live in vancouver BC where we have one bridge in particular that covers 8000m2 of surface area with a max height of 24.7 meters. Combine that with 43 inches of average annual rainfall and you get roughly 1.6 billion gallons of water per year. (0.6 gallons per sqft per inch of rain)
Using a collection efficiency of 80%, a 10 meter drop to a turbine with an efficiency of 93% and you get roughly 189.5mwh per year.
I'm still finalizing the designs along with cost and ROI but I hope to bring this to the working prototype stage in 2009.
Any thoughts, comments or questions would be very welcome.
Thanks for your reply!
We live in a 2 bedroom apartment in downtown vancouver and consumed 4.015mwh last year. At that rate the single bridge could power 46 apartment (homes) per year.
There are 11 bridges that I've calculated to be feasible so in practice it could generate a significant amount of power.
You're right in that I will have a hard time getting all parties on board. It's going to be all about convincing the right people that we need to not only conserve power but generate it from waste (water).
Another key point will be designing and engineering a system that can be built at low cost (relative) and low maintenance. The electric company here will pay from $84 to $112 per mwh from independant power producers, depending on the time of year. It just so happens that the most rain falls during the peak demand period here. so potentially 16k dollars per year in energy sales. Money tends to grease the wheels a bit when trying to push these ideas.
I'm not ready to give up! I'm going to try my best to get this on the right people's desks. If all that comes of it is getting more people to think this way then I will be half satisfied.
Cheers.
Hi trendsetter,
I know this seems petty, but watch your units! megawatt-hours is MWh (yes case matters) because if we ignore the "W" you said about 4 milliwatt-hours, which is 1 billion times less. It would be the energy needed to lift a can of coffee onto a shelf, not the energy to run an apartment for a year.
I hope everyone takes notice of this... ;^)
The Light is Green!
Hi!
I was working with my daughter (8 years old) in building a generator, that would light up at least a bulb, in showing we could make electricity with water in the household. We wanted to use the engineering principles of hydroelectric power plants. After two weeks of testing we came up with a model that would feed on running water. Of course, the basic observations expressed frustration since keeping running water from the faucet in to the turbine would turn out as a non cost effective way of creating electricity. Then, my daughter reacted. What if we could make a reservoir of water, like hydroelectric plants do?
In the conclusions, we suggested the use of rain as water source. To make it short the rain would be captured in the house roof. This storage would have a system that would move the water inside a draining tube (a running stream) captured by a turbine. The turbine of the generator would make the rotor spin thus creating electricity to power a home. If I am not mistaken roof reservoirs already exist, they are used to spray plants, discharge toilets and for car wash.
Also just look at Seattle Washington. It gets over 84% of it's power from hydro. They have some of the lowest electric rates in the country. You can charge as many electric vehicles and plug-in hybrids as you could fit in the state off peak and still have extra energy, and all clean.
Just imagine if we all used the best resources we have in our state like Texas with wind, Arizona with Solar and Washington state with hydro. If only we could harness the hot air in Wash DC !
as a small grower in northern new mexico, i (and most of my neighbors) get to take advantage of one of the most reliable of energy sources - gravity. our irregation system of over 1000 acequias (remember roman aquaducts ?) brings us water from high elevation snow melt. without getting into the particulars of our 300 year old system - i'll just say that many of us are looking for small generators we could use to power our farms and ranches by taking advantage of water flowing over short vertical drops in the system. it would translate into cleaner air, food and yes water as well as inspiration to keep people producing food locally. now the big question - are such hydro-generators available?
bob lesch
The first two questions are how big are the vertical drops, and how much water falls over them? That'll tell you how much evergy is available.
The third question is how much energy do you consume? With those answered you can compute whether or not the project makes economic sense to undertake.
If the idea appeals to you as a hobby or just plain fun then the ROI could be measured in centuries, and I'd still say have a good time. Kinda like asking what's the ROI on a ski trip, or a concert??? Well it's negative of course, but we still do those things for the fun it.
To determine is there's a solution available, you have to see a ROI that's measurable in years or months, then someone might be doing it for real.
I just read a very good book from the library. It was (The Citizen-Powered Energy handbook) . There were many good facts in it. The most amazing one I read was there are over 80,000 hydro dams in the USA but only 2,400 are used for power. Why not start using more of them for power. It seems many used to produce power but large utilities didn't want to be bothered with the small ones.
I wonder if they would lease them to some smaller enterprising companies that may want to bother. I'd love to have a home near one of these too small to bother with locations. Maybe it could only provide energy for a few hundred homes. That could be very green and pay for itself.
the solar stacks
I forgot to mention all the small hydro in Europe. They are very smart and can use the same water over and over as it travels down a large mountain. That sure seems smarter than just climbing the mountain with support people and leaving trash behind like many climbers do. We just have to be smarter.
solar stacks
Just check out Arizona Falls, sure it's not Niagara Falls but it does make clean energy in a desert. Also check out Roosevelt dam , lake Suarguro and many other hydro sources in AZ. If AZ can do it anyone can.
For small home hydro all you need is a small stream. Read home power and see many examples of people who use it and companies that make small hydro systems.
solar stacks
Remember chap that you don't have to have Niagra falls in your backyard to take advantage of water power. Yes, if you live in urban society then your choices will be severely limited. If you are out in the country and have a stream source near you then you can definitely take advantage. Here's an example that I found which illustrates using water power nicely:
Thought this might be of interest
http://www.youtube.com/watch?v=z900AKfwC5Y
I watched the video - that is very cool! I would love to know if there is a commercial product out there that would be simlar to the Vertile wind turbine that is advertised on the site - if not, probably would be a good idea as the video reveals, not a lot of water is need to generate enough power to turn some gears - probably more power than in a sustained wind of 10mpg... Just a thought.
Aloha!
Kona
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Hi Guys,
Nice to find a gem out there on the web such as you guys. I was wondering if anyone out there is using hydro electric power, or has heard of anyone using hydro electric power for consumer use? I understand the concept for dams and other major construction initiatives, but I was wondering if anything exists on a smaller scale that can be used for consumers? I assume that you'd have to have your own major source of running water, but perhaps there's a way to leverage hydro power more economically and more towards the individual or home use.
Thanks,
Jonathan