# Solar power...how much and how much? **URL:** \ **Category:** Great Debates\ **Created:** [March 3, 2009, 6:08pm UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170 "2009-03-03T18:08:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [March 3, 2009, 6:08pm UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/1 "2009-03-03T18:08:16Z")
Since I didn’t think we should continue to hijack the Nuclear thread I figured I’d move the question here instead and get people’s thoughts on solar and it’s potential, costs, drawbacks and benefits. In the other thread mention was made of the claim that all of American’s energy needs could be met by 100 sq miles of solar panels in Nevada. From [here](http://www1.eere.energy.gov/solar/myths.html): > [@](#): > > Myth 1: Solar electricity cannot serve any significant fraction of U.S. or world electricity needs. > > PV technology can meet electricity demand on any scale. The solar energy resource in a 100-mile-square area of Nevada could supply the United States with all its electricity (about 800 gigawatts) using modestly efficient (10%) commercial PV modules. > > A more realistic scenario involves distributing these same PV systems throughout the 50 states. Currently available sites—such as vacant land, parking lots, and rooftops—could be used. The land requirement to produce 800 gigawatts would average out to be about 17 x 17 miles per state. Alternatively, PV systems built in the “brownfields”—the estimated 5 million acres of abandoned industrial sites in our nation’s cities—could supply 90% of America’s current electricity. > > These hypothetical cases emphasize that PV is not “area-impaired” in delivering electricity. The critical point is that PV does not have to compete with baseload power. Its strength is in providing electricity when and where energy is most limited and most expensive. It does not simply replace some fraction of generation. Rather, it displaces the right portion of the load, shaving peak demand during periods when energy is most constrained and expensive. > > In the long run, the U.S. PV Industry Roadmap does expect PV to provide a “significant fraction of U.S. electricity needs.” This adds up to at least 15% of new added electricity capacity in 2020, and then 10 years later, at least 10% of the nation’s total electricity (PDF 674 KB). Download Adobe Reader Though I see no citations to back that up, let’s assume that is true for a moment (feel free to provide data either for or against the assertion if you like). What would this cost and how long would it take to build? I found this on [Scientific America](http://www.sciam.com/article.cfm?id=a-solar-grand-plan): > [@](#): > > ``` > * A massive switch from coal, oil, natural gas and nuclear power plants to solar power plants could supply 69 percent of the U.S.’s electricity and 35 percent of its total energy by 2050. > * A vast area of photovoltaic cells would have to be erected in the Southwest. Excess daytime energy would be stored as compressed air in underground caverns to be tapped during nighttime hours. > * Large solar concentrator power plants would be built as well. > * A new direct-current power transmission backbone would deliver solar electricity across the country. > * But $420 billion in subsidies from 2011 to 2050 would be required to fund the infrastructure and make it cost-competitive. > > ``` > [@](#): > > Solar energy’s potential is off the chart. The energy in sunlight striking the earth for 40 minutes is equivalent to global energy consumption for a year. The U.S. is lucky to be endowed with a vast resource; at least 250,000 square miles of land in the Southwest alone are suitable for constructing solar power plants, and that land receives more than 4,500 quadrillion British thermal units (Btu) of solar radiation a year. Converting only 2.5 percent of that radiation into electricity would match the nation’s total energy consumption in 2006. > [@](#): > > The technology is ready. On the following pages we present a grand plan that could provide 69 percent of the U.S.’s electricity and 35 percent of its total energy (which includes transportation) with solar power by 2050. We project that this energy could be sold to consumers at rates equivalent to today’s rates for conventional power sources, about five cents per kilowatt-hour (kWh). If wind, biomass and geothermal sources were also developed, renewable energy could provide 100 percent of the nation’s electricity and 90 percent of its energy by 2100. This sounds great. However: > [@](#): > > The federal government would have to invest more than $400 billion over the next 40 years to complete the 2050 plan. That investment is substantial, but the payoff is greater. Solar plants consume little or no fuel, saving billions of dollars year after year. The infrastructure would displace 300 large coal-fired power plants and 300 more large natural gas plants and all the fuels they consume. The plan would effectively eliminate all imported oil, fundamentally cutting U.S. trade deficits and easing political tension in the Middle East and elsewhere. Because solar technologies are almost pollution-free, the plan would also reduce greenhouse gas emissions from power plants by 1.7 billion tons a year, and another 1.9 billion tons from gasoline vehicles would be displaced by plug-in hybrids refueled by the solar power grid. In 2050 U.S. carbon dioxide emissions would be 62 percent below 2005 levels, putting a major brake on global warming. So, for debate…where are we with solar and how would we get to a large percentage of our energy needs being met by solar? How quickly (realistically) could we get there and how much (realistically) would it cost? Based on current technology and where the technology is going in, say, the next 10 years, how would it most likely be deployed and how much area might it take up? What are the potential environmental impacts? What are the potential maintenance impacts? I’ll be mostly away for the next several days until I fly home Friday, but will try and keep up at least at night from my hotel room. I’m really interested in seeing what folks here on the 'dope think of the potential and realities of solar today. -XT ---
**Author:** ![ITR\_champion](https://avatars.discourse-cdn.com/v4/letter/i/c67d28/32.png) [@ITR\_champion](https://boards.straightdope.com/u/ITR_champion)\ **Post date:** [March 3, 2009, 6:24pm UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/2 "2009-03-03T18:24:03Z")
There is, of course, the annoying fact that some parts of the country aren’t sunny all the time, as the desert southwest (almost) is. Nevertheless, solar could provide a substantial part of our nation’s energy needs right now, if only we had the political will to make it happen. We’re making substantial [advances in solar technology](http://www.businessgreen.com/business-green/news/2236140/irish-firm-launches-efficient) all the time, and there’s every reason to believe that with the right incentive, companies could accelerate the paces of their research quite a bit. Here’s what I would recommend. The federal government should make an announce that as soon as someone makes a 25% efficient solar panel beneath a certain cost, they will purchase 10 billion dollars worth of those panels. Basically like the X-prize, only multiplied by a factor of 1,000. That would get some serious interest from the major energy companies. ---
**Author:** ![E-Sabbath](https://avatars.discourse-cdn.com/v4/letter/e/e19adc/32.png) [@E-Sabbath](https://boards.straightdope.com/u/E-Sabbath)\ **Post date:** [March 3, 2009, 6:29pm UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/3 "2009-03-03T18:29:34Z")
I think orbital solar power has _way_ better potential, here, and I believe Obama’s mentioned something about funding it. ---
**Author:** ![elucidator](https://avatars.discourse-cdn.com/v4/letter/e/8edcca/32.png) [@elucidator](https://boards.straightdope.com/u/elucidator)\ **Post date:** [March 3, 2009, 6:58pm UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/4 "2009-03-03T18:58:41Z")
We are in a very peculiar position: we have trouble accessing energy, and we are awash in it, its like a fish who is thirsty. I don’t think solar power is quite ready for prime time yet, but its well on its way. Clearly, it can be a major factor in those areas where sunlight is so consistent and abundant, not so much in Portland. But I look to research in solar power more for its synergistic effect that for direct, practical application. The guys who invented the transistor did not realize they were inventing the personal computer, the guys who invented radar did not realize they were inventing microwavable popcorn. Most of our really big strides come less for “Eureka!” moments than from some tinkerer putting together two disparate discoveries to create a third. If we research solar power, we research transmission efficiency (from Phoenix to Portland, say). Research in the photo-electric effect is research into the very fundamentals of what energy is. The only real reason we haven’t had this breakthrough already is that energy has been relatively cheap, albeit self-destructive, for so very long. We are just really starting something that, had it been started 40 years ago when we dirty fucking hippies started bitching about it, might be already realized. We will almost certainly abandon our first efforts to practicalize solar energy, because we will discover something better in the process. That may seem like a waste of effort and money, but only if you forget that the effort and money is necessary for us to get the point where we can make such instructive mistakes. Cheap clean energy is just beyond our reach, tantalizing us. And if we can reach it, and I believe that we can, and we will…we will begin a golden age unlike any currently dreamed of. Even the poorest subsistence farmer will be blessed with mechanical energy far beyond any that he can bring to bear from his own muscles or from beasts of burden. On Spaceship Earth, energy is the only currency of any real value. Cheap clean energy can make the chasm between the haves and have-nots trivial and inconsequential. We’re the Americans. If not us, who? If not now, when? ---
**Author:** ![Strassia](https://avatars.discourse-cdn.com/v4/letter/s/e8c25b/32.png) [@Strassia](https://boards.straightdope.com/u/Strassia)\ **Post date:** [March 3, 2009, 7:05pm UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/5 "2009-03-03T19:05:02Z")
> [@E-Sabbath](#): > > I think orbital solar power has _way_ better potential, here, and I believe Obama’s mentioned something about funding it. What will be the transmission medium? ---
**Author:** ![E-Sabbath](https://avatars.discourse-cdn.com/v4/letter/e/e19adc/32.png) [@E-Sabbath](https://boards.straightdope.com/u/E-Sabbath)\ **Post date:** [March 4, 2009, 12:51am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/6 "2009-03-04T00:51:36Z")
I believe microwaves. Why? > **[Obama Transition Team Examining Space Solar Power - Slashdot](https://science.slashdot.org/story/08/12/20/219209/obama-transition-team-examining-space-solar-power)** > > DynaSoar writes "President-elect Obama's transition team has published for public comment a white paper entitled Space Solar Power (SSP) — A Solution for Energy Independence & Climate Change. The paper was prepared and submitted by the Space... The white paper linked here seems to cover quite a bit. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [March 4, 2009, 1:00am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/7 "2009-03-04T01:00:59Z")
> [@E-Sabbath](#): > > I think orbital solar power has _way_ better potential, here, and I believe Obama’s mentioned something about funding it. Assume you need a 10,000 square miles of the stuff orbiting the earth. Or some other reasonable number. Assume a weight for it. Find out what it cost to put a pound of something in orbit. Don’t faint when you see all those zero’s on the price tag. ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [March 4, 2009, 1:41am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/8 "2009-03-04T01:41:13Z")
Unfortunately, the costs are not magically vanished here on Earth, either. Those costs for mere earthly structuring, IMHO, are exceedingly optimistic. I’m not saying no one will use solar poewr. But solar is a support-item. It’s not the main show and probably can’t be. 25% power efficiency may not even be possible, at least one earth. > [@](#): > > Most of our really big strides come less for “Eureka!” moments than from some tinkerer putting together two disparate discoveries to create a third. If we research solar power, we research transmission efficiency (from Phoenix to Portland, say). Research in the photo-electric effect is research into the very fundamentals of what energy is. This is not impossible, but it is impractical, which is almost worse. Impossible ight be fixed, but impractical… yeesh. What you’re asking is not really humanly doable. You just can’t run transmission lines that long effectively. Or rather you can, but the requirements are obscene. You can even build it right now, but actually keeping the thing running would keep all the eingeers in America in coffee and nightmares for the rest of their lives. ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [March 4, 2009, 1:50am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/9 "2009-03-04T01:50:03Z")
> [@elucidator](#): > > We will almost certainly abandon our first efforts to practicalize solar energy, because we will discover something better in the process. That may seem like a waste of effort and money, but only if you forget that the effort and money is necessary for us to get the point where we can make such instructive mistakes. That’s a great point. Think back on home computers (hell, they weren’t even called “personal computers” back then!). My parents dropped around $3000 for an Apple IIe in the 1980s. We didn’t do much beyond playing games with it for the first few years. Eventually, when I got to high school, I used it to type papers. Getting closer to useful. Worth $3000? Probably not. Then you had Apple’s LISA, which was the first Mac-like GUI computer. $10,000. Did anyone do anything really important with it? No. But it paved the way for everything that followed. Now I can buy a comparatively superhumanly powerful Mac for $1000, or a PC for $200 or $300. And I can run my entire business on them. (My current Mac laptop, which runs my entire livelihood, cost around $1300 a couple of years ago.) The first cars were not the solution to massive transportation needs or transcontinental freight shipping. But they made later advances possible. ---
**Author:** ![Phlosphr](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Phlosphr](https://boards.straightdope.com/u/Phlosphr)\ **Post date:** [March 4, 2009, 1:55am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/10 "2009-03-04T01:55:53Z")
> [@xtisme](#): > > So, for debate…where are we with solar and how would we get to a large percentage of our energy needs being met by solar? How quickly (realistically) could we get there and how much (realistically) would it cost? Based on current technology and where the technology is going in, say, the next 10 years, how would it most likely be deployed and how much area might it take up? What are the potential environmental impacts? What are the potential maintenance impacts? > > I’ll be mostly away for the next several days until I fly home Friday, but will try and keep up at least at night from my hotel room. I’m really interested in seeing what folks here on the 'dope think of the potential and realities of solar today. > > -XT So many things need to be in place before these questions can be accurately answered. But before we get one enormous singular machine to power the nation, there are many smaller things that need to be in place. One not-so-small thing is there needs to be a paradigm change in order to get the money necessary to fund the infrastructure for a project that would fuel the nation. I think in the short term, state governments are going to run their own programs, continue to fund the ones in their states. This is already happening across the country. To give you an idea of how much the current administration wants to put towards alternative fuels, the state of Rhode Island got almost [50 Million](http://reed.senate.gov/newsroom/details.cfm?id=308340)for energy efficiency needs. This is huge for this small a state and it will go to fund infrastructure for alternative fuels. Solar power has come leaps and bounds in terms of technology, what we have to do is institute price reduction programs in more communities and really build it from the bottom up. Luckily for us this movement has been going on for quite a while and much of the infrastructure is already in place. Companies are growing and merging to form larger conglomerates, these are bringing the prices down somewhat… Companies like [Solar Wrights](http://www.alterisinc.com/index.php)in New England merged with a larger competitor and became Alteris. I think this is a move in the right direction, as more and more communities and states do this the more people will see it as mainstream. I think that may answer part of the OPs question. ---
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [March 4, 2009, 2:00am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/11 "2009-03-04T02:00:24Z")
My first reaction is that covering 100 square miles of desert with solar panels is going to cost way, way more than 400 billion. Also, how do you get all that energy from the Southwest to the places where people actually use the most energy, two thousand miles away? ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [March 4, 2009, 2:10am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/12 "2009-03-04T02:10:12Z")
A long time ago it cost more than $10,000 per pound to put things into orbit. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [March 4, 2009, 2:24am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/13 "2009-03-04T02:24:44Z")
> [@E-Sabbath](#): > > I think orbital solar power has _way_ better potential, here, and I believe Obama’s mentioned something about funding it. Think about it this way. You want the equivalent of 400! give or take power plants in orbit. Lets assume the power producing part wieghs or costs nothing. You are still proposing that you either use lasers or microwave generators/transmitters that can “process” a power level equivalent to a power station. How much would just that weigh? Its have to be the size of house! And something like thats never been built. Much less a bunch of em. And you are talking about putting hundreds, even thousands into orbit! Now you can just reflect the light down to an earth bound solar collector, but even those numbers are gonna be scary. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [March 4, 2009, 2:45am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/14 "2009-03-04T02:45:52Z")
Take [this](http://news.cnet.com/8301-11128_3-10170650-54.html) FWIW: > [@](#): > > Photon Consulting, which advises solar companies, this week released a summary of a study that predicts that a number of solar companies will hit a long-pursued industry target of $1 per watt by 2012. … “With $1/W for modules and $1/W for BOS (balance of system), solar electricity in sunnier areas will be (less than) $0.10/kWh by 2012, creating a large addressable market that is the grand prize in solar’s race to $1/W,” according to the report summary. > > The average retail price for electricity in the United States over the 12 months ending in November was 11.26 cents per kilowatt-hour for consumers and 10.24 cents per kilowatt-hour for businesses, according to the U.S. Energy Information Agency. Prices vary significantly within the country, ranging from below 5 cents per kilowatt-hour in Idaho to 15 cents per kilowatt-hour in New York, for example. > > Costs of solar electricity are falling through a combination of factors including better cell efficiency and improvements in solar manufacturing. Also, financing contracts where customers, usually a business, purchase electricity generated by rooftop panels over 20 or 25 years can result in a predictable and lower cost, according to analysts. … "Even at $0.15/kWh, the cost of solar power will be below grid parity for more than half of residential customers and 10% of commercial customers in the OECD (Organization for Economic Development countries), as long as grid electricity prices do not decrease through 2010. … And of course this does not take into account the incentives that may come as carbon is actually priced and paid for. In certain locations grid parity or better has already been achieved without even pricing the carbon. Hawaii for example - sunny and expensive to bring in coal or natural gas. (Although I wonder about using [geothermal there](http://www.punageothermalventure.com/About-Geothermal-Energy/13/geothermal-in-hawaii)!) And [First Solar in sunny Nevada](http://www.pv-tech.org/news/_a/has_first_solar_achieved_grid_parity_report_claims_the_numbers_add_up/) is reportedly producing power for less than traditional sources can. Solar will be a better choice for some parts of the country/world than others, just like wind is a better resource some places than others. But in those areas it can be rolled out very quickly as these smaller companies can ramp up production quickly. The limiting factor will be the supply of silicon feedstock (for photvoltaic systems) more than any thing else. A way around that feedstock limitation is being played with in [Israel.](http://www.theregister.co.uk/2008/01/25/faiman_negev_solar_plan/) > [@](#): > > the Negev plant uses large curved glass mirrors to focus sunlight onto a 10cm x 10cm area of cells. … the dish approach could be applied cost-effectively to large scale power plants, up to and including 10 per cent of the Sahara. “We’re effectively reducing the cost of photovoltaic by a factor of 1,000,” says Faiman. … Faiman explains how solar could fix Israel’s power requirements in 1 Gigawatt units. A single 1GW solar plant would be comparable in output to a large conventional power station, and would cost €1 billion to build. One plant would produce 2 Terawatt Hours of electricity every year, which would be enough to cover annual growth in Israel’s power demand. With each plant producing the equivalent of €200 million, the first five plants pay for the sixth. Assuming a 30 year lifespan for each plant, in year 29 you have to start building two per year (unless, presumably, you think you’ve got enough electricity by then, or you’ve run out of customers and/or desert). > > “This works after a fashion anywhere except Antarctica,” says Faiman. > > The amount of space the plants take up will depend on the efficiency of the cells - Faiman sees cells of 60 per cent efficiency being feasible, and it ultimately being possible to build 1GW plants on 5 km. sq. apiece. > > Gotchas? Solar doesn’t work at night, and Faiman concedes that storage of energy is therefore an issue. But if, say, you had a country that was switching over to electric cars, then much of the power for transportation would effectively be stored in batteries. Faiman also suggests that solar power could be used to split seawater into oxygen and hydrogen, giving you a supply of clean and portable fuel. ---
**Author:** ![elucidator](https://avatars.discourse-cdn.com/v4/letter/e/8edcca/32.png) [@elucidator](https://boards.straightdope.com/u/elucidator)\ **Post date:** [March 4, 2009, 3:19am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/15 "2009-03-04T03:19:54Z")
I think the wonder of the thing has us stymied, mentally stalled. Its too good, therefore it cannot happen. Of course its impractical, we haven’t done it yet! Fund lots of research, most of it small, some of it crackpot. Don’t try to put together the puzzle, concentrate on finding out the size and shapes of the pieces, get enough of _that_ knowledge and a tinkering, semi-intuitive mind is likely to throw a few of those pieces together, and run naked through the streets screaming in Greek. But I’d want to hedge my bets. I’d want to research alcohol more extensively than I have, jigger around with the innards of yeast and animals that can digest cellulose, for instance. Work on producing a small but strong, durable, and easily repaired engine than runs on alcohol, one cheap enough to be distributed to subsistence farmers world wide. Give Famine a bloody nose. Stuff like that. And, God? That’s why I should win the lottery. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [March 4, 2009, 3:40am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/16 "2009-03-04T03:40:50Z")
> [@xtisme](#): > > In the other thread mention was made of the claim that all of American’s energy needs could be met by 100 sq miles of solar panels in Nevada. Your site doesn’t say 100 square miles, but rather “a 100-mile-square area”, or 10,000 square miles. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [March 4, 2009, 3:42am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/17 "2009-03-04T03:42:26Z")
**'luci** , You mean an engine like [this](http://www.greencarcongress.com/2009/02/lotus-engineeri.html)? > [@](#): > > The Omnivore was designed in collaboration with Queen’s University Belfast and Orbital Corporation Limited Australia for high thermal efficiency when fueled on any alcohol-based fuel or gasoline. … The engine concept features a monoblock construction that blends the cylinder head and block together eliminating the need for a cylinder head gasket, improving durability and reducing weight. In this case, the application of a monoblock is facilitated by the absence of the requirement for poppet valves. … And yeast jiggering [like this](http://www.greencarcongress.com/2009/02/genetically-mod.html)? > [@](#): > > Professor Eckhard Boles at the Goethe-University Frankfurt, Germany and his colleagues have genetically modified the yeast Saccharomyces cerevisiae to express a newly identified enzyme to enable the fermentation of xylose (a 5-carbon sugar) as well 6-carbon sugars (e.g., glucose). A paper on their work appeared online 13 February in the journal Applied Environmental Microbiology. > > Cellulosic biomass, when treated, releases a mixture of hexose (6-carbon) and pentose (5-carbon) sugars, including glucose, galactose, mannose, D-xylose and L-arabinose. S. cerevisiae, the standard industrial yeast, offer fast sugar consumption, high yields and ethanol tolerance&mash;but is unable to ferment pentose sugars. … Others dream similar dreams … 🙂 ---
**Author:** ![lee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lee/32/7455_2.png) [@lee](https://boards.straightdope.com/u/lee)\ **Post date:** [March 4, 2009, 4:05am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/18 "2009-03-04T04:05:33Z")
My understanding is that photovoltaics are just not practical currently or in the foreseeable future. They are expensive to manufacture, manufacture results in toxic pollution, cells are delicate, etc. However, Using aimed flat mirrors in an array to reflect sunlight in order to heat salt until it is molten and then using that heat to generate power does have potential. The individual components are not prohibitively expensive to manufacture, they do not require rare elements, an excess of water is not used in the process, and once a facility is set up it keeps going for a long time with out much additional expense. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [March 4, 2009, 4:26am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/19 "2009-03-04T04:26:06Z")
**lee** my cites contradict your too expensive claim, the pollution is an issue but no different of one than for electronics, and the newer cells are not so delicate. But the [molten salt plan](http://www.sciam.com/article.cfm?id=how-to-use-solar-energy-at-night) is a valuable means of thermal solar that also can shift the power to night-time as needed. It’s getting closer to parity too. > [@](#): > > Near Granada, Spain, more than 28,000 metric tons of salt is now coursing through pipes at the Andasol 1 power plant. … Part of a so-called parabolic trough solar-thermal power plant, the salts will soon help the facility light up the night—literally. Because most salts only melt at high temperatures (table salt, for example, melts at around 1472 degrees Fahrenheit, or 800 degrees Celsius) and do not turn to vapor until they get considerably hotter—they can be used to store a lot of the sun’s energy as heat. Simply use the sunlight to heat up the salts and put those molten salts in proximity to water via a heat exchanger. Hot steam can then be made to turn turbines without losing too much of the original absorbed solar energy. … Melting salts at temperatures above 435 degrees Fahrenheit (224 degrees Celsius), however, can deliver back as much as 93 percent of the energy … Electricity from a solar-thermal power plant costs roughly 13 cents a kilowatt-hour, according to Glatzmaier, both with and without molten salt storage systems. > > That price is still nearly twice as much as electricity from a coal-fired power plant—the current cheapest generation option if environmental costs are not taken into account. … Ultimately, it will come down to how much value policymakers and consumers put on electricity that is renewable and emissions-free. “If we start valuing carbon and force a coal plant to go carbon-free via sequestration then we’re at or over 10 cents per kilowatt-hour from coal,” Mancini says. “Any of these technologies can get to that same 10 cents level with [molten salt] storage. Then the market will make the call.” ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [March 4, 2009, 5:05am UTC](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170/20 "2009-03-04T05:05:53Z")
[QUOTE=ZenBeam] Your site doesn’t say 100 square miles, but rather “a 100-mile-square area”, or 10,000 square miles. [/QUOTE] Yes, I realized that earlier but it was too late to correct. -XT [Next page](https://boards.straightdope.com/t/solar-power-how-much-and-how-much/488170.md?page=2)