Solar irradiance is ~1kw/m^2. 1GW/km^2, then. It goes up to 1.3GW/km^2 if balloons at stratosphere are used.
2012/6/1 Chemical Engineer <cheme...@gmail.com> > Daniel, > > Double check your math...i get 38 sq km per gigawatt during daylight with > clean mirrors > > > On Friday, June 1, 2012, Daniel Rocha wrote: > >> Well, at 40% efficiency, you need 1.6Km^2 for every gigawatt, So, 30X30 >> km2 will do it. Maintenance is hard but in terms of area, it is not >> something spectacular. >> >> Consider the reservoirs of the 2 most powerful hydroelectric dams: >> >> Itaipu reservoir has 1350km^2 http://en.wikipedia.org/wiki/Itaipu_Dam >> >> Three Gorges Dam has has 1045km^2 >> http://en.wikipedia.org/wiki/Three_Gorges_Dam >> >> And new technologies are being developed for peaceful purposes. Not in >> stupid drones. >> >> >> 2012/6/1 Chemical Engineer <cheme...@gmail.com> >> >> Jed, >> >> Just a fact check. You don't know how many times I have heard that " a >> solar site 100 miles to the side in the Mohave could generate all of the >> power requirements for the US". >> >> Some numbers based upon most efficient claimed CSP plant: (approx 2 to 3 >> times more efficient than PV but much more expensive) >> >> 370 MW Nominal generation requires 3500 acreas (largest, most efficient >> claimed US solar thermal plant being constructed) >> 350,000 mirrors (assuming they are clean) >> Generates power ~10 hours/day >> >> To cover peak US demand of 768,000 MW you would need 781 MILLION mirrors >> that only cover you 10 hours per day. The 110Mile x 110Mile plot is idle >> at night. With thermal storage you would need to more than double the area >> if you wanted to store during the day and generate at night, taking up > >> 60% of the Mohave. >> >> You can double this area for utility scale PV which, although cheaper is >> ~ half the efficiency of CSP/acre, in which case you would need a larger >> Mohave. You also need to develop weather technology to keep all clouds out >> of the desert... >> >> Also, your "Robots" will need to clean 781 million mirrors per month >> (monthly cleaning cycle) in the heat and sand of the desert. Plus where >> will you get the water to clean them or power for your army of hundreds of >> thousands of robots? If you cannot clean 781 MILLION mirrors per month you >> will need more, less efficient dirty mirrors and more space >> >> You will also pay 4 times more for this electricity than you are paying >> now. >> >> Also, from a strategic defense standpoint, it would be very easy for an >> enemy to blast one large nuke off over the desert and shatter all of those >> mirrors. >> >> I am OK with distributed PV on rooftops but get the crap out of the >> desert and give the BILLIONS to homeowners to subsidize installations. >> Solar City has a much better business model. >> >> I admire your creativity and regurgitating green fluff but I think you >> are drinking your own bath water and they are WASTING OUR MONEY >> >> >> >> >> >> On Thu, May 31, 2012 at 3:55 PM, Jed Rothwell <jedrothw...@gmail.com>wrote: >> >> Chemical Engineer <cheme...@gmail.com> wrote: >> >> >> You mention projects that are advancing human civilization and many were >> great investments. Are you OK spending billions on green projects that >> have 1/100th or less the energy density/potential of existing fossil fuels >> . . . >> >> >> Which projects do you mean? I am not aware of anything like that. >> >> The energy density of uranium fission plants is not as good as existing >> fossil fuels, because uranium ore density is so low, but I still prefer >> uranium reactors to coal-fired plants. >> >> The power density of solar cells is low but as long as they are cheap it >> does not matter. (Energy density is meaningless in a solar cell or wind >> turbine; the energy will last for billions of years.) We are not running >> out of space on the roofs of houses, or in the deserts of the southwest. A >> solar array 100 miles to the side could generate all of energy in the U.S., >> and there are hundreds of miles of empty land in places like Arizona and >> North Africa. >> >> >> >> Are you OK filling up the deserts with solar panels full of dust?. >> >> >> Better than building more coal fired plants and filling people's lungs >> with dust. It is not problem keeping the panels clean with robots. It does >> not take much water or overhead. >> >> Wind now supplies 2% of electricity. It could be increased to 20% with >> today's distribution technology. That would displace half of coal fired >> electricity. In North America, it would be way cheaper than adding that >> >> -- >> Daniel Rocha - RJ >> danieldi...@gmail.com >> >> -- Daniel Rocha - RJ danieldi...@gmail.com
