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Posted By: tonyWhat are our options for fuels in the future?
Posted By: tonyWhat are our options for fuels in the future?My list1) Solar2) Electricity3)Electricity from Nuclear4) Solar PV5) Electricity from Tidal, Hydro, Geothermal, small ammount of wind and wave
Posted By: fostertomLow grade (i.e. no higher grade than it needs to be, for the intended use) means effortless, maybe lo-tech, but very efficient collection/conversion of incident radiation.
Posted By: fostertomAs it can't be sold/transmitted, it's not a market commodity, so its 'price' won't be dragged up (regardless of 'real' cost) by substitutability with other, increasingly scarce energy sources.
Posted By: SteamyTeaBugger, going to have to do it now
Posted By: tonynon polluting
Posted By: SteamyTeaMy energy use is about 4.5 MWh/year (16200 MJ)1 kg of timber has about 16.2 MJ/kgSo I would need 1 tonne of timber (assuming all efficiencies are equal which they are not, hard to run my computer on wood).Growth of timber is around 7.5 kg per tree per year (for the first ten years).So I would need 133 trees.Tree density, for managed woodland, is 2500 trees per hectare or 4 m^2 per tree.So I would need at least 532 m^2.That would allow me to go for ten years without powering the house (while the trees grow) and then on the 11th year have it powered, which would be a nonsense. So realistically I would need 10 times that land area, 5320 m^2 (about half a hectare).This does not allow for any sequestration (so not improving the atmospheric CO2 levels, need another 2000 m^2 for that).Now lets us take a stab at efficiencies. Direct space heating and DHW could be pretty high at 70 to 80%. Electricity pretty low, probably around 20 to 30%. I estimate that I need 1000 kWh of electricity a year, leaving 3500 kWh a year for heating and water.So that is about 4000 kWh for electricity and 4500 kWh for heating, a total of 8500 kWh (30600 MJ). This boils down to 1900 kg of timber or 252 trees per year (tenth of a hectare @2500 trees per hectare).So on the rolling ten year timescale my house, with two occupants will need 1 hectare of wood land (10,000 m^2).Now if England has a surface area of 25000000 Hectares and assuming that half of it can be used to grow trees, then it can support 12.5 million houses like mine (25 million people). So about half of what we are at the moment.And that is just domestic use, take in the rest of the countries infrastructure and you are into probably a quarter of that at best.Even solar, with storage, will struggle.
Posted By: tonyAndrew, the problem with wood is that there is nowhere enough of it for everyone if they wanted to use it now so we would finish up with total deforestation and no wood for anyone even if we could live through the smoke and smog.
Posted By: renewablejohnYour making the classic error of starting with an annual fuel consumption and then trying to fulfill that consumption with a single fuel in this case wood
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