gizmag.com — Is solar a viable alternative energy source on a mass scale? Spain's opening of a commercial solar power plant and a test facility with another plant due to open this month. Powering 5000 homes from its 11 megawatt production.
Sep 14, 2007 View in Crawl 4
grumpyrainSep 15, 2007
Solar power is primarily limited by the amount of energy that actually makes it through our atmosphere to the ground. If you take a look at this radiation map from the bureau of meteorology ( <a class="user" href="http://www.bom.gov.au/sat/solrad.shtml">http://www.bom.gov.au/sat/solrad.shtml</a> ), you will see that areas of the top end would receive about 26 MJ per square metre per day. This is about 7.2 KWhr per square metre per day. Remember that this is the theoretical LIMIT, not what is achievable with todays technology. The best demonstrated cells are about 40% efficient give or take, and those cells are frightfully expensive stuff that you need a budget like NASA to even look at. You are looking at 20% or lower for cheaper cells, but lets say you have the quantum dot-modified photovoltaics MEG cells with 42% efficiency in labs for your entire 10km square. The maximum collectable power is then 7.2KW/hr/m^2 * 42% = 3KW/hr/m^2Collected power = 3000Whr * 10000 * 10000 = 300GWhr per day = 109.5 TWhr per year but with more common technology you are looking at about 30TWhr per year.So while this may be enough energy to replace all the energy used by the world, we do not have the infrastructure to transport that sort of energy. Your physics teacher would hopefully have explained why we build coal power plants close to populations and not in the middle of nowhere despite the associated health problems. The further you transport electricity, the worse the transmission losses. By definition, solar plants can only be built in certain areas where you have much sun and enough room to actually build a plant. The only major Australian city you could even build a plant near is Brisbane (or Darwin if you want to count that as major).
obxjdtSep 15, 2007
easy there Capt'n Photo shop....
fgsfdsSep 15, 2007
Global energy consumption averaged over 16TW a few years back. Not TWhr, but TW. If that common technology installation could provide all it's power over the year in one chunk, it would sate the world's power needs for less than two hours.Checking your units kills all kinds of easy solutions. :/Also, transmission losses are actually in the ballpark of 1%, which isn't all that bad if you factor in that some areas have a difference in solar radiation of FAR more than even 10%.
arpadSep 15, 2007
And let us not forget that the simple areal calculation is misleading. You need access, which increases the required area. You'll need power conditioning equipment and installations, i.e. transformers in transformer yards. More land area. Then there's electrical storage which is a whole 'nother issue since getting electricity 24/7 requires A) two or three times the area (or more) of solar cells as you'd need at high noon on a cloudless day and B) lots of additional money since power storage isn't, like sunlight and wind, free. Oh, and that power storage will require some land area dependent on the storage technology that's chosen. The cost of transporting the electricity has to be added. Line losses, as grumpyrain point out, mean more electricity in to get the necessary amount, out. Since this is giga- or tera-watts of electricity it'll cost quite a bit to move from the middle of the desert, which is where everyone puts this stuff, to where people live. Trouble is, sticking 'em in a desert will be tougher then anyone lets on. As soon as you've got a surveying crew checking out a location you'll have some enviro-wackos who would simply die if their particular bit of God-forsaken desert was besmirched by hundreds of square miles of artificial solar cells. Oh why can't everyone live simply, close to nature and leave a light footprint on the planet? And get that f-ing solar power array out of my pristine, beautiful-in-its-starkness landscape. Any of you who are love-smitten by the idea of a solar-powered future care to contend with the folks who want not a blade of grass crushed under the heavy foot of industrial civilization? Probably you'd end up ranting into a mirror seeing as how the people who're enraptured by a solar-powered humanity are the same folks who'd like to see 90% of the human race vanish.