Solar Energy and Hydrogen

There is often the question why not build solar powerplants out in the desert ? Well, solar panels require surface area and they require
sunlight with both things being available in the desert. I suppose the answer is that while alternating-current can be transmitted long distances, the distances are probably held to about 200 miles.
But Los Angeles and surrounding metros are near to the desert and sure enough there is a 354 MW solar powerplant in the Mojave Desert. Now these large solar powerplants don't use solar panels to produce electricity but use solar mirrors to heat water, make steam, turn turbines, and then produce electricity.
But here's an idea or question:
Why not use solar mirror powerplants in the desert to make hydrogen from pumped water and then send the hydrogen further distances in pipelines than electricity could be transmitted on power lines ?
Well, I'll answer my own question and say that likely there is more power to be had from the steam than from the hydrogen production.
But don't forget, there are solar powerplants in the desert.
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And solar panels in the desert would not require any water while solar mirrors making steam would require water. It's a strange combination of fundamentals but there are solar mirror powerplants in the desert.
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200 miles is nothing for a large transmission line with very littel in losses, especially DC lines (Tesla had limited foresite)
We prefer to get over 40% of our generatef energy to be **NOT*** lost. Hydrogen ranges about 3% delivery rate, according to experts. It's a waste.
And solar panels in the desert would not require any water while solar mirrors making steam would require water. It's a strange combination of fundamentals but there are solar mirror powerplants in the desert.
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Dear PolicySpy:

We'd sure love the jobs...

No issues with that. Any well-defined problem has a solution. Microwave beams, superconductive buried power lines.

Yes. Solar cell panels (so far) barely make up the energy cost to form them, in their service life. Additionally, they are toxic, so potentially difficult to dispose of at the end of that life. Lawyers like deserts too.

Or better still, just pump water. Fluid power systems can be very energy efficient.

It is beast we know and can deal with. Loss of hydrogen, embrittlement problems and such, are major issues.

No. First of all, most powerplants end up using steam, and the steam can be operated in a closed loop, requiring no makeup. Second of all, some solar power plants use other fluids for carrying solar energy from place to place, like molten sodium...

I repeat myself, when under stress. I repeat myself, when under stress. I repeat myself, when under stress.
David A. Smith
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What about the waste heat rejected to condense the steam at the outlet of the last turbine?
If you're near a river or ocean then you have a convenient large heat sink, if you don't have a large body of water then evaporative cooling towers are the next choice. I haven't run any numbers, but I would argue it's a substantial use of water.
Lance *****
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Dear Lance:

Here in Arridzona, we use grey water, which everyone is afraid to drink.
David A. Smith
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That might explain why they're made in China.
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The loss of investment income, or the cost of loan interest, on the solar PV installation usually exceeds the payback rate of income from solar PV installations, on home systems.
The manufacturers aren't usually losing money of the ones that haven't gone bankrupt or live on Gov. grants trying to produce a product.
dlzc wrote: I keep seeing this claim,but have a question. How can it be that solar cells "barely make up the energy cost to form them"? If this is true, wouldn't the manufacturers be losing money selling them? They have to pay for every unit of energy they use to make them. And energy can't be the only cost to manufacture them

.
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You're not up to date on solar cells:
from Wikipedia:
"...Energy payback time and energy returned on energy invested
The energy payback time is the time required to produce an amount of energy as great as what was consumed during production. The energy payback time is determined from a life cycle analysis of energy. The energy needed to produce solar panels is paid back in the first few years of use.[76]
Another key indicator of environmental performance, tightly related to the energy payback time, is the ratio of electricity generated divided by the energy required to build and maintain the equipment. This ratio is called the energy returned on energy invested (EROEI). This should not be confused with the economic return on investment, which varies according to local energy prices, subsidies available and metering techniques.
Life-cycle analyses show that the energy intensity of typical solar photovoltaic technologies is rapidly evolving. In 2000 the energy payback time was estimated as 8 to 11 years[77], but more recent studies suggest that technological progress has reduced this to 1.5 to 3.5 years for crystalline silicon PV systems[71].
Thin film technologies now have energy pay-back times in the range of 1-1.5 years (S.Europe).[71] With lifetimes of such systems of at least 30 years[citation needed], the EROEI is in the range of 10 to 30. They thus generate enough energy over their lifetimes to reproduce themselves many times (6-31 reproductions, the EROEI is a bit lower) depending on what type of material, balance of system (or BOS), and the geographic location of the system.[78]..."
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Your first paragraph indicates the rest is all a big exageration also. Your wikipedia article is incorrect.

You're not up to date on solar cells:
from Wikipedia:
"...Energy payback time and energy returned on energy invested
The energy payback time is the time required to produce an amount of energy as great as what was consumed during production. The energy payback time is determined from a life cycle analysis of energy. The energy needed to produce solar panels is paid back in the first few years of use.[76]
Another key indicator of environmental performance, tightly related to the energy payback time, is the ratio of electricity generated divided by the energy required to build and maintain the equipment. This ratio is called the energy returned on energy invested (EROEI). This should not be confused with the economic return on investment, which varies according to local energy prices, subsidies available and metering techniques.
Life-cycle analyses show that the energy intensity of typical solar photovoltaic technologies is rapidly evolving. In 2000 the energy payback time was estimated as 8 to 11 years[77], but more recent studies suggest that technological progress has reduced this to 1.5 to 3.5 years for crystalline silicon PV systems[71].
Thin film technologies now have energy pay-back times in the range of 1-1.5 years (S.Europe).[71] With lifetimes of such systems of at least 30 years[citation needed], the EROEI is in the range of 10 to 30. They thus generate enough energy over their lifetimes to reproduce themselves many times (6-31 reproductions, the EROEI is a bit lower) depending on what type of material, balance of system (or BOS), and the geographic location of the system.[78]..."
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Try backing up you unsupported statement.
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Simple math if you can multiple more than two figures together.

Try backing up you unsupported statement.
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I don't really believe that hydrogen produced from water is commerically viable...but wanted to think about hydrogen production.
But think about North Africa near the Mediterranean Sea. A solar powerplant could make electricity but where would the demand for the electricity be ? So the solar powerplant could take the electricity, make hydrogen, and pump the hydrogen to the nearest port. At the port hydrogen could be liquefied and loaded onto tankers for export.
Now a solar powerplant that uses mirrors to heat water for steam must have a source of water. Well, the Mojave Desert has the Mojave River. It's just a situation of a desert next to mountains and the river flows out of the mountains. Obviously, the desert is only irrigated at the river. Now I don't know if the solar powerplants in the Mojave Desert get their water from the Mojave River or elsewhere but wanted to explain water in the desert.
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Well, I can take a quick look at web sources on hydrogen-from-water.
The energy efficiency of producing hydrogen from water with electricity could be 50% to 80%. But that doesn't include the energy lost in making the electricity. However, there is a High Temperature Electrolysis that uses both steam and electricity and that would seem to fit well with a solar mirror powerplant.
I suppose it would be a rare situation of some location that could build a solar powerplant but not need the electricity.
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I forgot to mention another point:
Hydrogen for fuel cells should come from electrolysis so as to have the required purity.
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Dear PolicySpy:

Your choices are to have a thermal neutron source and wait for them to decay into hydrogen, or chemically strip the hydrogen from some other molecule. Currently, hydrogen is removed form fossil fuels.

Could just pressurize water, and use the pressurized fluid stream to act as the "energy carrier".

Snicker...
Elsewhere.
Wells.
David A. Smith
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It appears that hydrogen for fuel cells must be made by electrolysis for purity.

The idea is to export hydrogen from locations where solar mirror powerplants are effective.
Hydrogen can be pumped to ports, liquefied, and loaded onto tankers.
Finally, there is a high-temperature electrolysis that seems to be a good fit with solar mirror powerplants.
I suppose the bottom line is how long it takes to pay for the plant.
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Let me add a calculation...

...
Lets say you wanted to deliver a terawatt, and lets say you pumped the pressure on the water to in excess of 60,000 psi (so that biogrowth was not possible)
60,000 psi = 4,137 bar http://en.wikipedia.org/wiki/Hydraulic_machinery#Basic_calculations 1,000,000 kW * 600 / 4,137 = 145,000 liters/min This is a large force main (55 mgd), and some big thick-walled pipe to go 250 miles, and you'd want probably at least three pipes, and some sequencing of which was under max pressure (to keep all pipes sterilized in turn).
But energy delivery could be on the order of 90-95%, rather than 20-30% by making hydrogen first.
David A. Smith
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dlzc wrote:

To keep fluid friction losses down and control erosion inside piping, you typically have to keep the velocity under 10 ft/s (3 m/s). So to get your 145,000 liters/min you need a pipe diameter of just about 1 m.
To contain those kinds of pressures, you're talking a pipe wall on the order of 15 inches thick of high grade steel (39-inch pipe @ 60,000 psi =>2.4e6 lbf retained by two pipe walls of 100ksi steel plus safety margin). What is 250 miles of such pipe going to cost you?
I don't have my Crane book with me, but if I remember tomorrow at work I'll run an estimate of the losses in 250 miles of extremely smooth pipe 39 inch diameter with 10 ft/s water flow. I can tell you this much, it won't be pretty.
And how much are the losses in pressurizing this water? Even if the pipe itself is perfectly leak-tight, the pumps to reach those sorts of pressures are not 'off-the-shelf'. Positive displacement pumps have seal-losses and at high head situations a phenomenon where the small compressibility of the water itself causes another form of loss pump.
If hydrogen is a non-starter, this is worse from a practical engineering standpoint.
daestrom (posted from alt.solar.thermal)
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Dear daestrom:

Let's assume 0.1 ft/s, since we have to go so far, and want to minimize losses. Also, water hammer won't be such a problem, which will allow for a smaller factor of safety.

Figure 300 of them then. 100 outbound, and 200 inbound.

You'd only have to buy it once. This is not too different from the drill pipe the ocean platforms use. And figure expansion joints

Pressure losses will consume all power delivered, or more, at that speed.

... by the way, you leak check this pipe the same way you check for high pressure steam leaks... where the bristles of a broom fall off by being severed by the inaudible jet, is where the leak is.

They are, but not at these displacements.

Engineering can fix it, if it were financially desirable. Engineering cannot fix hydrogen.
You don't need to put any more effort into this. The OP does not seem at all concerned with this notion.
David A. Smith
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