Originally Posted by
Bill Dufour
What about the theory of Hydrogen made for renewable power? How will that get shipped through non existent pipes?
I will also add they are not considering the carbon impact of replacing a electric heat pump every few decades. My floor furnace was made in 1948 and still works fine. of course the efficiency is no as high as newer models that require electricity. In Berkeley no homes have air conditioning just furnaces.
Bill D.
Hydrogen has a number of issues, one of which is efficiency of conversions.
Let's start with 100 units of electric power, produced by some renewable means (solar, wind, etc.) and use that to do electrolysis of water. The energy contained in the hydrogen you get from that electrolysis is about 70% of the input energy, so now you have 70 units of energy.
Then, you get to one of the major problems - how to transport the hydrogen. You either have to have a way of producing hydrogen close to where it's going to be consumed or you have to compress it and transport it. Pipeline is the cheapest but there not much hydrogen pipeline. Compressing it and transporting it by truck is expensive. Hydrogen has the lowest amount of energy per volume of fuels. But let's be generous and assume that it takes 10% of the energy to compress and transport it. That gets us to 67.5 units of energy.
Then, the hydrogen is put into a fuel cell which is about 60% efficient, and that gets us 40.5 units of energy to go into the motors on the car. The motors are about 90% so we get to use about 34.5% of the energy we started with.
Looking at an electric battery car, let's start with the same 100 units of electric power, produced from renewable sources.
Transporting that energy to the charging station uses about 5% of the energy, which gets us to 95 units of energy.
A battery is about 90% efficient so the power to the electric motors is 85.5 units of energy.
The motors are about 90% efficient so the power we get from that 100 original units of energy is about 77 units.
Due to the losses in producing and using the energy from hydrogen, hydrogen is likely to be an expensive fuel if not heavily subsidized.
Mike
[One other thing is that a battery powered car can recover some of the expended energy when the car slows down, or the car is going downhill. There's no reasonable way to recover that energy when a fuel cell is used.]
Last edited by Mike Henderson; 08-29-2019 at 3:43 PM.
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