Solar panel farms

[madd1]

A few questions if you please:
With the flat sunny terrain of the Western deserts, why have we not built massive solar power farms? Is the technology just not available yet? Would 100 square miles of solar panels not provide enough energy? For that matter, how much energy would a farm of that size create? How big would one have to be to power Los Angeles?

Thank you.

[Whack-a-Mole]

I can't answer most of your questions but I did hear recently on NPR that solar power still doesn't money out compared to fossil fuel (coal & oil). Solar cells are actually pretty inefficient even when located in perpetually sunny places (remember they only produce electricity for 8 or so hours a day).

As teh cost of electricity rises these sorts of methods come closer to being viable but oil and coal (and maybe nuclear) will reign as the energy of choice for many years to come unless someone envents a very high efficiency solar cell.

[Phobos]

I don't have the numbers, but my impression is that it's still too expensive compared to other types of power generation. Solar collectors are not the most efficient things. So far, it seems like the technology is best suited to powering mobile units or remote locations. But I too would like this tech to be better developed.

countdown to the appearance of Anthracite and Sailor to give us the facts on (and probably against :) ) solar power

Just imagine the Environmental Impact Report you would have to write to build a 100 sq mi. solar panel farm! :eek:

[tracer]

madd1 wrote:

How big would one have to be to power Los Angeles?
During the day, the amount of solar energy that reaches the surface of the Earth is about 900 Watts per square meter -- assuming your collecting surface is aimed straight at the sun. At midwestern latitudes, on average, the sun is above the horizon about 10 hours per day.

The City of Los Angeles has a population of over 3 million. If we assume 1 household per every 3 people, and an average power usage of 1 kiloWatt per household, then Los Angeles pulls down an average of around a billion Watts. I don't know if this guess is anywhere near close to being accurate.

So: 1 billion Watts, divided by 900 Watts per square meter, divided by the fraction of time the solar panels can produce power (10/24ths), is: 2.6 million square meters. (Assuming 100% efficient solar panels.) This would be 2.6 square kilometers.

[gazpacho]

One big reason against massive solar power projects is that there is not a good cheap way of storing electricity.

http://www.caiso.com/SystemStatus.html

The link shows the california electricity useage. Notice that the load is close to peak well after the sun has gone down. As other people have indicated the cost of a power plant is higher for solar than say gas or nucular so much so that the fact that you get free fuel does not make them cost effective yet.

Tracers calculations are extremly optimistic. You will not be able to extract 900 Watts per square meter when the sun is directly over head. You will not get 10 hours of sun a day. 1 kW per house is somewhat low. Very low if you have an air conditioner. I know they were just a wag to get an idea of how big the plants how have to be.

[Chronos]

The main problem with solar panels is that they have a very long payback time: It takes a lot of energy to make them in the first place, and a typical solar panel will take about ten years to collect that much energy (if it even lasts that long). Ten years to pay back your capital is a pretty bad investment, in either money or energy. It's possible that someday panels will be invented which are cheap and efficient enough to be practical, but it looks like that's a long ways away.

[tracer]

gazpacho wrote:

Tracers calculations are extremly optimistic.
What, you mean we don't have 100% efficient solar panels? ;)

[Sam Stone]

Right now Solar is very inefficent and expensive. If we ever do go with Solar energy, it may not be photovoltaic cells as being discussed here. Rather, we'll use large collectors to heat water and drive turbines. Or something similar.

I've often wondered about hybrid power sources. One of the problems with solar and wind is that it's unreliable and unresponsive to peak loads. But what about a hybrid solar/nuclear plant? One that shares the same turbines, but has an automatic exchanger that selects either nuclear or solar heating. As the sun goes down (or it gets cloudy), nuclear starts to take over the chore of heating the water.

My thinking is that the nuclear plant could operate on a much lower duty cycle, thus creating much less waste.

Of course, you wouldn't have to use nuclear. You could do the same thing with other types of plants.

Anthracite, if you're out there do you have any thoughts on this concept?

[Una Persson]

Sorry guys, been out of town a bit to Poland, working with those other power plants - the ones that burn coal.

[countrygirl]

I don't have the numbers, but my impression is that it's still too expensive compared to other types of power generation. Solar collectors are not the most efficient things. So far, it seems like the technology is best suited to powering mobile units or remote locations. But I too would like this tech to be better developed.

countdown to the appearance of Anthracite and Sailor to give us the facts on (and probably against :) ) solar power

Just imagine the Environmental Impact Report you would have to write to build a 100 sq mi. solar panel farm! :eek:

Could you give me more info


could you give me more info on this subject? We have a large solar panel farm moveing into our area and am looking for lots of info?

[campp]

The storage of power (batteries of any sort) continues to be one of our toughest technological hurdles. If we can get a good handle on storage, then things like solar become more attractive.

[Reply]

Right now Solar is very inefficent and expensive. If we ever do go with Solar energy, it may not be photovoltaic cells as being discussed here. Rather, we'll use large collectors to heat water and drive turbines. Or something similar.

I've often wondered about hybrid power sources. One of the problems with solar and wind is that it's unreliable and unresponsive to peak loads. But what about a hybrid solar/nuclear plant? One that shares the same turbines, but has an automatic exchanger that selects either nuclear or solar heating. As the sun goes down (or it gets cloudy), nuclear starts to take over the chore of heating the water.

My thinking is that the nuclear plant could operate on a much lower duty cycle, thus creating much less waste.

Of course, you wouldn't have to use nuclear. You could do the same thing with other types of plants.

Anthracite, if you're out there do you have any thoughts on this concept?

What would be the advantage of having them at the same geographical location rather than just being tied into the same grid?

Are the best sites for solar power typically the best (or even compatible) with nuclear/wind/hydroelectric/coal/etc.?


So: 1 billion Watts, divided by 900 Watts per square meter, divided by the fraction of time the solar panels can produce power (10/24ths), is: 2.6 million square meters. (Assuming 100% efficient solar panels.) This would be 2.6 square kilometers.

Wouldn't 100% efficient panels be a few lightyears ahead of where we are now? I thought the typical efficiency was more like 10%-20%?

[Exapno Mapcase]

The other huge problem is distribution and transmission. Here in the east it is almost impossible to get the rights to build new high-powered transmission lines. Even in the west I would imagine that the rights are just as difficult and the costs soar when you can closer to built-up areas.

[Chronos]

The storage of power (batteries of any sort) continues to be one of our toughest technological hurdles. If we can get a good handle on storage, then things like solar become more attractive. Even with good storage, solar still isn't ready for prime time (though good storage would certainly help wind). On the other hand, the way to get better solar energy is for government and/or big businesses to subsidize a few farms right now, at a loss, in order to develop the technologies to make it cheaper or more efficient. Just because it's not practical right now doesn't mean it'll never be.

[Enginerd]

A few questions if you please:
With the flat sunny terrain of the Western deserts, why have we not built massive solar power farms? Is the technology just not available yet? Would 100 square miles of solar panels not provide enough energy? For that matter, how much energy would a farm of that size create? How big would one have to be to power Los Angeles?

Thank you.

One of the problems that's specific to the area you're asking about is cooling processes. Water cooling is the most efficient method, but water's a scarce resource in the desert southwest, and even the vast empty basins tend to be fully allocated. Air cooled systems take a big hit on efficiency, especially during the hottest time of day (which happens to correspond to the peak demand time). Even with air cooled generation, water is still needed to maintain regular plant operations and to keep the collectors clean.

With an air-cooled system, you need 1000 acres (~1.56 square miles) of solar collectors and 100 acre-feet of water per year (around 32 million gallons) per MW of usable power (numbers from a presentation I attended a couple of weeks ago, focused on solar power generation in the Amargosa desert). 100 square miles of solar collectors would provide around 64 MW. As a guess, I'd say that the power demand from LA is measured in thousands of MW.

[Magiver]

A real world example is an array they just built in my area.
It cost $5 million dollars and it produces 1.1 megawatts which serves 150 homes. That is $33,000 per home. Solar cells are notorious for poor performance at night so unless they are built to North Korean standards they require another power source for 14 + hours of the day or the addition of more than double the number of cells plus a storage medium.

What is probably more useful on a dollar/watt basis (out west) are solar thermal generators and they slowly building more of them but the big hurdle associated with that is the distance involved in transmission. You have to take losses into consideration. Great for places like Phoenix but not so much for far away cities.

Solar cells are not space limited, it's the cost involved.

[levdrakon]

I've often wondered about hybrid power sources. One of the problems with solar and wind is that it's unreliable and unresponsive to peak loads. But what about a hybrid solar/nuclear plant? One that shares the same turbines, but has an automatic exchanger that selects either nuclear or solar heating. As the sun goes down (or it gets cloudy), nuclear starts to take over the chore of heating the water.Wind, solar (more or less) and nuclear are all good for base load power, but not peak load or load following. For now, that's coal or gas or if you're lucky, hydro.

[Gangster Octopus]

All of these answers about cost and storage are great, but another major reason they have not been built is because the desert is not a wasteland that you can just go ahead and build on willy nilly. It is a wilderness environment that has many environmental hurdles to overcome. Another problem is that the land is not unowned land. Much of it is owned by private trusts, individuals, the military, the Bureau of Land Management, etc.

[Crafter_Man]

The problem with PV power is that it's not fuel; it is an energy vessel. It does not generate net energy. In essence, it destroys oil that could otherwise be used for positive net energy production.

[Chronos]

The problem with PV power is that it's not fuel; it is an energy vessel. It does not generate net energy. In essence, it destroys oil that could otherwise be used for positive net energy production. I understand what you're saying, there, and there's a lot of truth to it with current technology, but it's not inherently true for solar the way it is for, say, hydrogen. With current technology, it takes a lot of energy to make a solar cell, and a lot of time for that cell to pay that energy back. So you put in a lot of energy at the start, and then gradually get energy out of it over time. This is practical for a pocket calculator or a satellite, but not energy-efficient. However, it's reasonable to suppose that, at some point in the future, the technology will have improved to where solar panels can actually be a practical net energy source.

I will nitpick, though, that solar panels even now can generate net energy; it just takes an impractically long time. And the energy used to make them in the first place is more likely to have come from coal, not oil.

[Santos L Halper]

Could you give me more info


could you give me more info on this subject? We have a large solar panel farm moveing into our area and am looking for lots of info?

Since Phobos hasn't been on the board in over six years, he most likely can't give you more info... :)

[Enginerd]

The problem with PV power is that it's not fuel; it is an energy vessel. It does not generate net energy. In essence, it destroys oil that could otherwise be used for positive net energy production.

In addition to Chronos's post, I'd note that most of the production-scale solar developments in the works today aren't photovoltaic (PV) cells. Rather, they're concentrating solar collectors (http://en.wikipedia.org/wiki/Concentrating_solar_power) that focus the sun's energy on a heat transfer fluid and use the thermal energy of the fluid to drive electrical production.

[johnpost]

i agree that solar thermal makes some sense for solar intensive areas.

[beowulff]

I understand what you're saying, there, and there's a lot of truth to it with current technology, but it's not inherently true for solar the way it is for, say, hydrogen. With current technology, it takes a lot of energy to make a solar cell, and a lot of time for that cell to pay that energy back. So you put in a lot of energy at the start, and then gradually get energy out of it over time. This is practical for a pocket calculator or a satellite, but not energy-efficient. However, it's reasonable to suppose that, at some point in the future, the technology will have improved to where solar panels can actually be a practical net energy source.

I will nitpick, though, that solar panels even now can generate net energy; it just takes an impractically long time. And the energy used to make them in the first place is more likely to have come from coal, not oil.

Five years ago the energy payback time for a solar panel was only 2 years - it has to be even better now. 2 years in "impractically long?"
What is the energy payback time of a 1GW Nuclear generator?

[Chronos]

I hadn't hears about panels with a payback time that short. Are they in mass production?

[Rhythmdvl]

Just imagine the Environmental Impact Report you would have to write to build a 100 sq mi. solar panel farm! :eek:

Could you give me more info


could you give me more info on this subject? We have a large solar panel farm moveing into our area and am looking for lots of info?

I don't think their granting categorical exclusions (releases from having to do an environmental impact statement) for projects that risk zombie apocalypses.

[beowulff]

I hadn't hears about panels with a payback time that short. Are they in mass production?

This was based on a study that one of the writers for Home Power did awhile back.
A Goolge search turns up this quote:
We just discovered a recent, very detailed study about solar panel energy payback time in the January 2001 issue of Home Power magazine. This study, by Karl Knapp, PhD, and Teresa Jester, finds payback time for a standard module to be about 3.3 years, and 1.8 years on a thin-film panel. The study factors in energy costs for ALL parts of the panel and manufacturing process
So, it was even longer ago than I remembered.

[Gangster Octopus]

In addition to Chronos's post, I'd note that most of the production-scale solar developments in the works today aren't photovoltaic (PV) cells. Rather, they're concentrating solar collectors (http://en.wikipedia.org/wiki/Concentrating_solar_power) that focus the sun's energy on a heat transfer fluid and use the thermal energy of the fluid to drive electrical production.

Actually this is not true, most production-scale (assuming you mean utility scale) solar devlopments are indeed now Solar PV. At least in California I know this to be the case.