Carcano said:
Much better reference. Thanks. My impression is that
relatively local use of (rice?) straw is both economically sound and environmentally beneficial. That is in your reference, the distance it is transported (24Km =15miles) to the small village (24,000 people) and used for district heating system is what makes this true. I doubt if it can scale up by even a factor of 4 (Transport 60 miles and small city, still less than 100 thousand people). I.e. I doubt it can still remain economically viable, but its environmental benefits would remain and perhaps justify some subsidy to make it viable for small cities.
For modest and large cities, coal fired district heating is a good idea, widely used in Sweden and some other northern European countries, including part of Germany. It is little used in the USA, and when it is, it is usually the very local distribution of the "spent steam" exhaust of a electric power plant. Hot water district heating can serve a wider area.
I know a little about all this because for a couple of years I lead a study team investigating CASES, Community Annual Storage Energy System. (CASES, used ice making machines to economically extract heat from water in winter during peak heating requirements and the surplus heat of the larger buildings of the community* and stored the ice (or chilled water produced from it in local aquifer if available, and more economical) for cooling need the next summer. Large, efficient, ice machine making flake ice, not cubes, can have a COP = 4. I.e. get four times as much heat out as electric power in but the real saving is the reduction of electric power consumption in summer air conditioning requirements. Can think of their winter heating as free.)
The idea of annual storage is now being used in some places, but mainly in colder locations with two aquifers, and no ice machines. One aquifer is warmed by the heat removed from buildings in summer and the other naturally chilled in winter, perhaps by spraying its water into the cold air and reinjection into the aquifer at a different, but not too distant location. (Not very efficient the first year or two as the ground mass of aqufer is being charged with "cold.")
Unfortunately, the psychological orientation of most Americans against anything that resembles "socialism" or "community cooperative systems" is too strong for these more efficient systems to be accepted.
When oil is too expensive for them to use for heating their home and they are sitting in cold houses under blankets, perhaps they will think differently.
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*Few realize that modest and large cities typically produce net surplus heat in their larger buildings, even on cold winter days, than the city requires. (Cold outside is taken in and the heat is just dumped to the environment - why city air is warmer than the suburban air.) This heat is too low a quality (temperature) to be used directly but if feed to locally distributed ice making machines or other heat pumps serving individual homes, it is a much better heat source than the cold winter air that the typical home heating heat pump extracts heat from. I.e. with it, their COP can be much higher, reducing electricity requirements for the same heating.
I think conversion of soybean fields to cane, where US does not compete, and global demand for both sugar and alcohol is rising rapidly is more likely true than the "official reason." Fact that Brazilian Real is very strong, is making prices in dollars convert to less profit for farmers paying help in Real etc, but sugar/alcohol and OJ prices are increasing more rapidly than grain prices, so this also drives conversion of soy fields to cane, but few will cut down orange trees in the short term, so OJ production should remain high.
