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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 but they are not a source of generation capacity. Hydrogen is more like a battery than a supply of energy. Hydrogen can be liberated from water by using energy. ...


9

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 transparency platform where you can see the hourly actual generation per production type for Ireland: It's hard to pick out a trend just by looking at a day ...


9

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 raindrops, as they fall, have very little energy - very little mass, and pretty low velocity too. Once they've fallen on high land, they've still got a lot of ...


5

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 efficiency will be much lower than the peak, as a lot of plants are old and have efficiencies around 60% (although some have been refitted to boost efficiency). ...


4

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 and storing huge amounts of water is a mature technology - people have been doing that for ages. And since gravity isn't very energy dense storing decent amounts ...


3

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 any specific data on it, but would expect it to be minimal if you charge the reservoir during off-peak (cheaper) hours and discharge it during the morning ramp. ...


3

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 has a mass 1000 kg and the value of g is 9.8 m/s^2. The amount of energy 1000 L of water would have after falling 20 m is, U = 1000(20)9.8 = 196,000 J Given ...


2

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 it can lift to a higher elevation) smaller. Eventually you reach the point where the water is moving so slowly that it doesn't contain enough energy to operate ...


2

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 when there is no wind and sunshine. The key here is that the hydrogen is generated in a sustainable manner: using renewables, not from steam reforming of ...


2

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 engines as well; if the hydrogen and oxygen sources are sustainable, then the combustion engine will be as sustainable as the fuel cell (minus potential efficiency ...


1

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", pumping water from the bottom of the dam to the top*. The Niagara Falls installation sits well above the Falls, and has separate pumps: they pump from the high ...


1

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 dedicated hydrogen bottle store-room( many 5 ft tall steel bottles); fortunately no bottles were damaged. I also had a lab where we used bottled hydrogen for ...


1

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 affect that outflow during the time required to fill to the desired level. Once achieved the original outflow volume will need to be maintained. Whether this is ...


1

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 used to supply energy but the energy available for typical volumes and "heads" is so small as to make the exercise not worthwhile. An exception is if you are in ...


1

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 increase with distance. Finally, an uncovered reservoir in an arid climate will suffer evaporation losses. Therefore, there isn't a single answer to this ...


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