Solar Power quote on Wiki...

rexxz · Tar Sands Joined: Jun 27, 2006 Posts: 29

Sorry if this has been addressed before, but I just wanted some clarification on this. I read this little bit on the wikipedia page, and I was wondering what it means exactly:

"Solar cells can presently convert around 15% of the energy of incident sunlight to electrical energy. If built out as solar collectors, 1% of the land today used for crops and pasture could supply the world's total energy consumption. A similar area is used today for hydropower, as the electricity yield per unit area of a solar collector is 50-100 times that of an average hydro scheme."

Now, especially the bolded part catches my attention. I'm not personally making any claims whatsoever on it, but does that mean what it implies?

Andy · Intermediate Crude Joined: May 16, 2004 Posts: 519

That statement is in fact corrrect. An area of approximately 200,000 or so square miles can theoretically supply all human energy needs. Scale of resource is not the issue with solar, it is speed of ramp up, cost, materials requirements and storage that are the issues.

Any one of these three diverse solar technologies on their own can theoretically supply human energy needs.
1. Solar thermal (electric and thermal)
2. Solar Photovoltaic
3. Wind

I could add Ocean thermal as well but that is really solar thermal electric by another name.

In fact, it has been calculated that the total land requirements of solar including mining, waste disposal facilities , fuel processing facilities and transportation infrastructure for fuels is on the same order of magnitude as that needed for coal, oil, nuclear etc.
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For ionizing radiation “…the human epidemiological evidence establishes—by any reasonable standard of proof—that there is no safe dose or dose-rate…the safe-dose hypothesis is not merely implausible—it is disproven.” Dr. J.W. Gofman 4

rexxz · Tar Sands Joined: Jun 27, 2006 Posts: 29

Hm. So how feasible is it to actually do much good for a large scale solar transition, and how much would be economically viable?

EndOfSewers · Heavy Crude Joined: Apr 20, 2006 Posts: 112

This has been touched on before, using one solar company's own figures in terms of cost/watt, it would take tens of trillions of dollars to build a system to supply the energy needs of just the US.

rexxz · Tar Sands Joined: Jun 27, 2006 Posts: 29

EndOfSewers · Heavy Crude Joined: Apr 20, 2006 Posts: 112

Pyron Solar

At the bottom of the main page they say $3-4/watt. Somewhere else on their website they say how many terawatts they need.

Kez · Posted: Tue Aug 22, 2006 12:15 pm Post subject: Re: Solar Power quote on Wiki...

The energy from the sun provide massive amounts of power, collecting it is the problem. In my study of photosynthesis, it appears to be around 1% effective of capturing that energy that we can later use in the form of calories.

Solar panels are around 15% now, but the problems are:

The energy isn't liquid, so you'd have to replace the entire car fleet/gasoline system.

You have to store the energy somehow (the sky does not remain free of clouds and rain 100% of the time). If you use portable hydrogen cells for example, then you lose 70% or so of the energy right off the bat converting the electricity to store that energy using hydrogen. If you use normal batteries, then they need to be replaced and maintained in mass every few years.

It is incredibly expensive because purifying the panel components has to be done at $100 million fabrication plants.

Good silicon is used for electronic parts. If the government suddenly decided to go nuts on solar panels, then there would be a mad rush on silicon which would likely double or triple the price. Just like the Boston big-dig, they would quote $2 trillion and it would end up being $10 trillion and only half as big as proposed.

There are not enough plants in the world to get that many panels up and running anytime soon, and it would take a few years to build new plants.

Still, with all the problems, it can be done, but I think rather than a few large complexes, that each city should have it's own local solar panels and start getting it up and running and expand on it in the future. However, I sure don't see my city or any city near me doing anything like this, or even thinking about it. Instead, they are expanding the roads near the new walmart and home depot that just moved in. Those bring them taxes, solar panels only bring them big deficits to their budgets.

Mrshaba · Coal Joined: Aug 25, 2006 Posts: 6

Arguments for Solar

I changed my mind about solar power when I noticed yearly production had passed the GW mark in 2004. Production in 2006 will come close to 2 GW. Despite a silicon shortage, production projections for 2010 are 5-10 GW. At some point the continued growth of solar photovoltaics is going to start changing peoples' opinons.

I recognize solar is currently expensive and is growing mainly because of subsidies. In regards to the future price of solar the thumbrule for historical cost reductions in the PV market is 20% price declines for every doubling of production. This learning curve is typical of many manufacturing processes. Currently, prices have reversed the downward trend due to a silicon shortage but competive forces will push prices down in the future. The price of a solar kilowatt hour is 25-50 cents today. If you assume a continued growth rate of 25% per year we will have about three doublings by 2015. If you assume a 15% price improvement per doubling then solar will cost 15-30 cents per kilowatt hour in 2015. I think these are reasonable predictions. I also think these predicted prices are clearly competitive in places like California, Hawaii and Japan. I'm open to counter arguments.

In regards to the diffused nature of solar I don't see a problem. At 100 square feet per KW there is more than enough room to power a properly designed home with rooftop mounted panels.

In regards to energy storage I don't see this as an immediate problem. Solar and the grid work together just fine. As far as long term solar fuel goes here's an idea.

Methanol can be produced from a chemical reaction between hydrogen and CO2. The CO2 can be captured from the atmosphere using technology at the proof of concept stage. Electrolysis can produce hydrogen at a rate of 1 kilogram per 50 kilowatt hours. Using these givens the potential output of a solar-methanol farm near Tucson would be around 35,000 gallons/acre/year using 13.5% efficient panels.

Just some thoughts.

Mrshaba · Coal Joined: Aug 25, 2006 Posts: 6

No opinions on solar economics eh? I thought that back of the envelope methanol farm idea was impressive. More productive than biofuels by an order of magnitude, doesn't require arable land, no fertilizers, CO2 neutrality and scalability. If you ballpark the numbers with a 18% efficient SunPower panel you get over 50,000 gal/acre/year and that's with the electrolysis middleman.

Is there a chemist around who can provide information concerning the electrocatalytic conversion of CO2 and H20 into methanol? What is the efficiency of this process? What are the pluses/minuses? Any good links out there?