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Originally posted by twhiteheadI do use gas but I calculated how much electric I would use if I didn't and used all-electric heating instead. Part of the reason why solar energy won't be enough to meet all my demands in mid-winter is because that is when I use the most heating ( + much less solar energy at that time of year ). I guess a partial solution to that is to super-isolate my home but, again, I am confronted with unmanageable set-up costs.
I assume that doesn't include heating? Do you use gas?
I guess this is the kind of reason reason why the whole world isn't rushing to go 100% renewable any day soon; the problem isn't the long term economics as renewables can be made in most cases to pay for themselves in the long run, nor is it the physical feasibility; the main problem is the generally frightfully high initial set-up costs that seriously put governments and/or people off. Now, if only we can find a way to slash those initial set-up costs to something much less painful...
Originally posted by sonhouseThat would double all my estimates, so the UK is basically going to be at maximum sane capacity by 2020.
In space the amount of solar energy is 1355 watts per square meter. Maybe 1000 watts per square meter on the ground and then 20% of that, so about 200 watts per square meter out the door.
Originally posted by humyHeat pumps give you about three times the bang for the buck but of course that also is expensive. There is a solution calling for two 20,000 gallon pools of water, one being cooled in winter , the other warmed in summer and the warm water heating the house in winter and the cool water cooling it in summer. There is that tiny detail of building 2 underground well insulated 20,000 gallon pools however🙂 And the cost of super insulating your house which lowers the size needed for both pools.
I do use gas but I calculated how much electric I would use if I didn't and used all-electric heating instead. Part of the reason why solar energy won't be enough to meet all my demands in mid-winter is because that is when I use the most heating ( + much less solar energy at that time of year ). I guess a partial solution to that is to super-isolate my home bu ...[text shortened]... if only we can find a way to slash those initial set-up costs to something much less painful...
I guess the cheapest way is to build your house into a hillside where the mass of the hill keeps the house at a uniform temperature and you have well insulated windows in front. That pretty much takes care of everything.
Of course there are only a limited number of hills available for such construction.
The best solution, I think, is to bite the bullet and get the very best insulation you can get. That saves in both summer AND winter.
Originally posted by humyThen I am actually surprised that solar would be adequate in some other winter months. Most home solar setups do not cater for cooking or heating which are done via gas, and the geyser via a solar geyser system (with out electricity).
I do use gas but I calculated how much electric I would use if I didn't and used all-electric heating instead.
the main problem is the generally frightfully high initial set-up costs that seriously put governments and/or people off.
That may be a good argument for individuals, but not a good argument for governments, especially when it comes to new power stations. Governments and businesses routinely invest large amounts of money in power stations. Here in SA they are currently planning a number of new ones including nuclear, and a massive hydroelectric scheme in the Congo. But coal is probably also on the cards.
Now, if only we can find a way to slash those initial set-up costs to something much less painful...
Some places have schemes where a company invests and essentially rents the solar equipment to you. If done right, you end up paying a monthly bill lower than you currently do. I believe that is part of the reason for the success of solar in Germany.
Another way would be to include solar when building houses, that way its part of the mortgage.
I currently can't go solar because I am renting a flat, so there isn't the option.
Originally posted by SoothfastSolar could theoretically, supply all the worlds electricity demands, and possibly all the worlds energy demands. But it is simply not the most economical option, and there is no good reason for it to be the only source.
I think solar power can at best cover only 25% of global energy demand, unless world population is brought down considerably.
Solar has advantages in certain situations and not in others. If a home owner in a reasonably sunny part of the world wants to be more self sustainable, solar is pretty much the only option with wind being a possibility in some places. But for utility scale power, wind is one of the cheapest options right now, with hydroelectric, and others also being good options in suitable locations.
Originally posted by SoothfastHere's a some statistics from the Wikipedia page on renewable energy:
The solution can only be a combination of renewables: solar power, wind, tides, hydroelectric, geothermal, and the blubber in Rush Limbaugh's buttocks. I think solar power can at best cover only 25% of global energy demand, unless world population is brought down considerably.
Current total energy use: 16 TW = terrawatts
Available energy:
Non renewables, total reserves:
Coal: 900 TW years
Uranium: 90 - 300 TW years
Oil: 240 TW years
Natural gas: 215 TW years
Renewables:
Tidal: 0.3 TW
Waves: 0.2 - 2 TW
Geothermal: 0.3 - 2 TW
Hydro: 3 - 4 TW
Biomass: 2 - 6 TW
Wind: 25 - 70 TW
Solar: 23 PW (peta-watts)
Solar appears to beat everything else put together by 3 orders of magnitude. I don't know if that figure just takes total insolation and multiplies it by the area of the world, or is a little more sophisticated and only includes realistic coverage with current available technology.
The catch is that there's a life-cycle carbon price with both wind and solar power. Although for solar it's about 1/10th of the carbon use of burning coal. In fact I'd imagine that it's entirely because the energy used to make the solar cells comes from non-renewables so the more renewables are used the more that figure will fall.
It appears from this that solar can supply all our energy needs a thousand times over.
[1] http://en.wikipedia.org/wiki/Renewable_energy
Diagram in section Overview:
http://en.wikipedia.org/wiki/Renewable_energy#/media/File:Global_energy_potential_perez_2009_en.svg
It seems to be someone's pet project and could easily be the work of an undergraduate, so these figures should be taken with a pinch of salt.
The blubber in Rush Limbaugh's buttocks will only last another 20 to 25 years.
I did a quick handwavy calculation. I assumed that total insolation is 1000 W/m² [1]. The total area of the Earth getting sun is πr² where r is the radius of the earth - this is the cross-sectional area facing, not the actual area, and deals with curvature effects, nighttime and so forth. The amount of land is 28.2% of the earth's surface. I assumed solar cell efficiencies of 25% [2].
Total area facing = 1.275 E+14 m²
Total average insolation of land = 35.96 Petawatts
Total recoverable solar energy = 8.99 Petawatts (note he's over this by a factor of 3)
Assume 0.1% coverage of all land with solar panels.
total solar energy generation using 0.1% of all land = 8.99 TW.
I think the figure from the Wikipedia page makes the dubious assumption that the entire earths land surface would be covered in solar panels. It also uses a theoretical peak efficiency of 75% for PV cells. I used the figure for best commercially available cells.
Nevertheless, if there are no clouds solar power could be the major source of energy, with other sources there to cope with absence of sun.
[1] http://en.wikipedia.org/wiki/Insolation
[2] http://en.wikipedia.org/wiki/Solar_cell#Efficiency
Originally posted by DeepThoughtIt is not intended to be an estimate of what we would actually use, but rather of total potential. I think the key point is that its better (or even necessary) in the long term to exploit sunlight directly rather than use the same sun light to create biomass, or other secondary products.
I think the figure from the Wikipedia page makes the dubious assumption that the entire earths land surface would be covered in solar panels.
I don't know why the restriction to land surface is in place. If we ever go that far, it makes more sense to put vast solar farms at sea rather than fill the land with solar panels then move all farms to the sea. (although fish farming is likely to become a greater percentage of our farming in the future, it doesn't require much space.)
Originally posted by twhiteheadWhat I am personally hoping is solar, wind, wave, geo-thermal and such are stopgap measures till we figure out fusion economically. ITER is one step along that road but it might take till the year 2100 before fusion gets economically available. I just hope all the other non-fossil sources of energy keeps us going till then.
It is not intended to be an estimate of what we would actually use, but rather of total potential. I think the key point is that its better (or even necessary) in the long term to exploit sunlight directly rather than use the same sun light to create biomass, or other secondary products.
I don't know why the restriction to land surface is in place. If we ...[text shortened]... ely to become a greater percentage of our farming in the future, it doesn't require much space.)
I think eventually fusion reactions will be small enough to power cars, aircraft and spacecraft.
Originally posted by sonhouseWhy? Because its a romantic concept to an engineer? There are no real reasons why fusion power should be the best option, and unless you are right that very small power plants can be built, it will always be worse than solar socially. The great thing about solar is that to a large extent it can be owned by individuals thus reducing the effect of energy politics that currently plagues society. Fusion power at least initially would be similar to nuclear power - high investment, corruption prone government /mega corporation run nightmares.
What I am personally hoping is solar, wind, wave, geo-thermal and such are stopgap measures till we figure out fusion economically.
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Originally posted by twhiteheadfusion power is probably way off into the future anyway:
Why? Because its a romantic concept to an engineer? There are no real reasons why fusion power should be the best option, and unless you are right that very small power plants can be built, it will always be worse than solar socially. The great thing about solar is that to a large extent it can be owned by individuals thus reducing the effect of energy po ...[text shortened]... o nuclear power - high investment, corruption prone government /mega corporation run nightmares.
http://www.newstatesman.com/sci-tech/2014/11/forever-20-years-away-will-we-ever-have-working-nuclear-fusion-reactor
I guess that, by the time we have decent and economic fusion power plants, renewables would be so well developed and advanced ( + possibly of-the-grid storage + supergrid ) that there simply wouldn't be any incentive or point at all to go mostly fusion power -and there never will be, at least on Earth. But if we ever have colonies on the moons of the outer planets where there is very little solar or wind energy, just perhaps we might have mostly fusion power there. I think it would be pretty stupid to put human colonies there but I am thinking in terms of AI robot colonies to do research and/or industrial work.
Originally posted by twhiteheadThe problem is the 23 Petawatts figure is completely misleading, there is no way more than a tiny fraction of that could be accessed. Besides, if you think about it the figure for wind energy must include some of that solar energy. I'm wondering what he's done with the other figures.
It is not intended to be an estimate of what we would actually use, but rather of total potential. I think the key point is that its better (or even necessary) in the long term to exploit sunlight directly rather than use the same sun light to create biomass, or other secondary products.
I don't know why the restriction to land surface is in place. If we ...[text shortened]... ely to become a greater percentage of our farming in the future, it doesn't require much space.)
Blocking the sun out with huge arrays of solar panels is not going to be great for marine habitats. Also fish farming is not an ecologically neutral activity.
Originally posted by DeepThoughtI agree. But he did state what the figure referred to. However, I doubt he equally calculated the maximum theoretically possible wind energy, but rather the reasonably harvestable wind resources, and he should have attempted the same for solar.
The problem is the 23 Petawatts figure is completely misleading, there is no way more than a tiny fraction of that could be accessed.
Once could for example build a massive lake at the top of some of the best rain fed mountains (or even artificial mountains) and go all out hydroelectric, but instead, he will have calculated the reasonably utilizable rivers.
Blocking the sun out with huge arrays of solar panels is not going to be great for marine habitats.
Most of the ocean doesn't have too much 'marine habitats' that we need to worry about.
Also fish farming is not an ecologically neutral activity.
I never suggested it was. Nor is any farming for that matter. I merely believe that we are likely to obtain a larger proportion of our protein from marine farms in the future. Properly managed they can be less ecologically harmful than farming on land. (not that I am claiming they will be properly managed).