On 28 June 2014 04:31, Richard R. Pope wrote: > You can't do it that way. Your numbers are about 50 percent too > high. No. His numbers were about 100% too low. ie doubling them would give the amount of energy per area available from solar in the short to medium term. One would need to look into the assumptions made when arriving at the figures quoted, but if utilising solar immediately in the vicinity of the pV panels, then power output of around 200 W/ m^2 of actual panel will be the norm in the next few years. Average daily insolation for various locations can be found on a number of sites. One goodone is www.gaisma.com eg here is the page for Houston, Texas http://www.gaisma.com/en/location/houston-texas.html The kWh/m^2/day for a typical day by month for Houston is Variable III IIIIV VVI VIIVIII IXX XIXII Insolation, kWh/m=B2/day2.51 3.13 4.13 5.175.52 5.745.98 5.614.94 3.992.84 2.34 This is real world data that can be expected to be typical of what you would really see after having taken real world factors into account. Worst case is about 2.3 equivalent full sun hours in December and best is just under 6 hours in July. The average is about 4.4 "sunshine hours" per day annually. Real world delivered energy from PV is rising steadily and module outputs of 20% plus will become the norm within 5 years. So 4.4 hours x 1 kWh/m^2/hr x 20% =3D 880 Watt hours or 2.3 x higher than the figure Kerry supplied. Actual will vary with circumstance, and Houston is not meant to be representative - just an example. You have to allow for cloudy days. Calm days. The short days and > long days up north. Gaisma contains enough information to allow you to do this easily. > Remember the massive storage plant to offset this. > Well you are going to have high losses in these storage plants that have > to be accounted for. And where are you going to put the storage plants > since the solar power plants are using up all of the available land. > Storage is a separate issue as is matching solar peak to national demand peaks. The above 20% is for domestic PV to mains AC. (Modern inverters achieve an awesome 98% + efficiency so DC and AC energy levels are very similar). Dometic thermal solar is 30% - 60% efficient if well designed and implemented. New storage technologies are fighting their way to the surface and the ongoing search is liable to turn up a solution superior to current best practice "some time". eg a recently announced organic 'flow battery' may do just that - or more likely will prove to be one more step on the journey. Hot water heating is a highly efficient means of energy storage and addresses the biggest single domestic energy use. Take your numbers and cut them in half. In fact you may find that that > is even too high by a factor of two. You will be a lot closer to the > real amount of power that is available from geothermal, wind, and solar. > See above > Also remember that at best you are only going to recover ten > percent of the solar energy that actually reaches the surface. 20% + see above. Wind only > recovers 2-3 percent of the available energy and wind farms have huge > maintenance requirements. Where are you going to put the shops. > Wind costings are well enough known. Whether a system is expensive in maintenance or capital or operation of staff or remediation or ... is not very important in these calculations. What matters when looking at economics is the IRR or the genuine cost per unit of energy produced. Wind is NOT currently competitive with traditional sources but is getting increasingly good. Geothermal is 70 to 80 percent efficient but the maintenance issue is > even larger. Irrelevant. See above. > This is the trap that the solar and wind people fall in to. > The do their calculations at 100 percent efficiency. It just isn't so. > No. Anyone who has any clue at all in the industry has access to good data and uses it appropriately. There will always be starry eyed dreamers who have not a clue, but that does not mean that there are not a majhority who understand the business. > The true efficiency is only about 8 percent of the total available > energy if you can get the best balance of geo, wind, and solar. % of actual is irrelevant - EXCEPT if you can make money on it and get only 8% of the available energy then that is marvellous as it will be increasingly possible to up percentage efficiencies. Getting > this balance is extremely difficult and in our political climate it is > impossible. No energy source is properly costed without distortions. Nuclear most certainly isn't. > What are your numbers at 8 percent? > Irrelevant (and a wrong percentage). > Remember if you use the land for one type of power generation it is > no longer available for another type of power generation or for a > storage plant. Hardly a universal truth. If I put eg enough solar thermal collectors on my roof o supply ALL my hot ater I'd have no problem storing the heated water in the house under the collectors. > You have to have fission and coal. It is the only way to > get the power densities necessary to generate the huge amounts of energy > necessary to run a country the size of the US. For some values of "necessary". > This is true for any > advanced civilization. For some values of "advanced". > Sorry for the wake up call. > .... Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .