13 votes

Are fuel cell electricity generators a sustainable way of making electricity?

No. There is no readily available supply of net-positive-energy hydrogen on Earth, where most human power usage takes place. Hydrogen fuel cells may be a useful component of a total energy system ...
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10 votes
Accepted

Is electricity used at night more likely to be renewable?

In Ireland, electricity is equally likely to be from renewable sources during the day as during the night ENTSO-E, the European Network of Transmission System Operators for Electricity, provides a ...
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  • 11.3k
9 votes

Is it possible to convert rain drops to energy?

It's possible, but the best way to do it was devised over a century ago: hydro power. Let the high land collect and channel lots of rain, and then put a turbine on the channel. The problem is that ...
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  • 14.6k
5 votes

grid-based gravity assist power generaiton

I think you have exactly the right term already. The Institute of Electrical Engineers use "gravity energy storage" and wikipedia has a Gravity Battery page. The main issue is that pumping ...
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  • 3,755
5 votes

What's the average efficiency of pumped hydroelectric energy storage facilities?

In this question about rooftop hydro I covered the efficiency question almost as an aside. I can't find an actual plant with efficiency over 80%, only claims that that might be possible. The average ...
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  • 3,755
3 votes

What's the average efficiency of pumped hydroelectric energy storage facilities?

Energy Storage Association cites round trip efficiencies above 80% http://energystorage.org/energy-storage/technologies/pumped-hydroelectric-storage As for the evaporation question. I don't know of ...
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3 votes

How much electricity does 1,000 liters of water per meter of height fallen generate in various hydro generator arrangements?

The potential energy of anything falling from a height is given by U = mgh, where: U is the potential energy in joules m is the mass in kilograms h is the height in meters Now, 1000 liters of water ...
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  • 3,207
2 votes

Could multiple ram pumps be used to fill a watertower for a pico hydroelectric system?

Every time water flows through a ram pump it loses energy (slows down). That means there is less energy available (in the water) for the next ram pump, which will make its yield (the amount of water ...
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  • 2,744
2 votes

Are fuel cell electricity generators a sustainable way of making electricity?

So, are fuel cell generators sustainable? Yes. The hydrogen will be generated using spare electricity when wind and/or sunshine are plentiful. It will be stored, and used later to create electricity ...
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  • 3,025
2 votes

Are fuel cell electricity generators a sustainable way of making electricity?

The focus on electricity is probably secondary: Any energy source can be converted into electric energy. The focus on fuel cells is probably secondary, too: Hydrogen can simply drive combustion ...
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1 vote

grid-based gravity assist power generaiton

The industry term is "pumped storage" and it's used all over the place at a large scale. Some systems, like Oroville Dam, reverse their turbine-generators to be "motor-pumps", ...
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1 vote

Is hydrogen a good way of storing energy from excess hydroelectric generation?

No, it is too tricky to handle for the general public. When it leaks ( not -if it leaks) , it will rise in a storage area and may reach explosive conditions. I once saw a brick wall blown out of a ...
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1 vote

How can I build an ecologically conscious dam on a small brook?

Currently, if I understand correctly, the pool overflows into the brook with sufficient flow for fish to escape and to maintain water quality in the pond. Raising the level of the pond will only ...
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1 vote

Is it possible to convert rain drops to energy?

Would it be possible to convert water drops into energy using a dynamo? A heating mechanism could then be used to transform the water back to a vapor to start the cycle again. Any rainfall can be ...
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1 vote

What's the average efficiency of pumped hydroelectric energy storage facilities?

As a Mechanical Engineer, I know the efficiency of the pump(s) and generator will be a function of the head or the height difference between the upper and lower reservoirs. Also, the line losses will ...
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