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Solar & Thermal Systems, Inc. |
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The Light is Green |
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Neutral |
Between Clean and Dirty are Carbon Neutral formsThis is a very long list of variations on a few basic themes; all of these are forms of stored solar energy. 1) Agriculture -- food for humans and animals, ag-waste returned to fields or burned as fuel, grain for Ethanol C2H5OH (EtOH) and other alcohols, esters, etc., oilseeds for cooking and bio-diesel and bio-plastics. 2) Forestry -- lumber, paper, lignin, chips, firewood, etc., although lumber and furniture may take a little longer before retuning the carbon to the atmosphere. 3) Landfills -- all are sources of methane whether we use it or not. Probably the last step for organic matter from Agriculture and paper that doesn't wind up in the sewer system. Synthetic Fuels -- Anywhere From Clean to DirtyWhen synthetic fuels (synfuel for short) are clean they are not energy sources, and when they are energy sources that are not as clean. Synfuels can be a complex mix of fossil fuels, clean energy and carbon neutral feed stocks. When viewed rationally like this they represent the energy from the primary energy sources stored in a new form more suitable for commercial application than the original form. The Great Plains Synfuels(TM) plant in North Dakota, where I was during construction at back in '83, converted lignite or brown coal into Synthetic Natural Gas (SNG), was not originally carbon neutral, but the SNG was more valuable than the coal. The SNG captured ~40% of the energy of the primary coal if memory serves. When a synfuel is derived from a fossil fuel the only possibility for it to be clean is it the CO2 released by the burning of the original fossil fuel is sequestered. When we hear about Clean Coal today this is what they are referring to. In the grand scheme it is important to note that cleaning fossil fuels represents a loss of a significant fraction of the primary energy contained in the raw fuel. This does not come without significant additional costs. Synfuels can also be made from carbon neutral feed stocks, and even incorporate low energy materials like metal ores and water. It's even possible to add energy from the true clean sources and make lots of synfuels. But the energy still came from the primary source. The synfuels are simply the meant to transport the energy to where it's needed. The products range from Hydrogen for fuel cells to metals for batteries like lithium, and reactive chemicals like nitric acid and hydrazine for rocket motors. None or there are energy sources! Let me say that again, none of the synthetic fuels are energy *sources*; that's not to say they are not valuable, they are products that compete for primary energy. |
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