The USA generates about 20% of its electricity from natural gas; 699.6 billion kWh  were produced from gas in 2004. This consumed 6,020,335 million ft^3 of gas  (roughly 6.2 quads) of our total consumption. The net efficiency was roughly 39%; the other 61% of the energy turned into heat. Only 31% of this gas-fired generation was in combined heat and power plants; the heat from the other 69% was discarded.
The 60.5 million households using natural gas for heating in 2001 used a total of 3.32 quadrillion BTU of gas for heating , or roughly 55 million BTU each. The 8.5 million households heating with fuel oil  used 0.58 quads, or 68 million BTU each. The 6.6 million households heating with LPG used 0.28 quads, or 42 million BTU each. Together, these 75.6 million households used a total of 4.18 quads of heating fuel in 2001, averaging 55 million BTU each.
Commercial buildings are similar. In 1999, commercial space used 1.76 quads of natural gas and .17 quads of fuel oil  for heating. Together, the fuel used for heating residential and commercial real estate came to 6.1 quads. This is nearly the same amount of energy as all the natural gas used for electric generation, and most of it is consumed during the half-year of the heating season.
Home-heating oil is almost the same as diesel fuel, and both LPG and natural gas are high-octane motor fuels; every home and business which has heating fuel delivered in tanks or pipes could run a generator to provide its electricity too. The generator converts part of the fuel's energy to electricity and the rest to heat. Creating the heat where heat is needed is better than making it where it has to be discarded.
Cogenerating electricity with heat creates large efficiencies and could have eliminated the prospect of a natural gas shortage this winter... if we had done it. How much? Here's an example:
Suppose the typical house uses 55 million BTU of gas for space heat over the heating season (average 367,000 BTU/day over 150 days) and consumes 15 kWh/day of electricity over the same interval (2250 kWh total). If the electricity was generated in a 39%-efficient gas-fired plant, it would require 19.7 million BTU of gas. The total for heat and electricity would be 74.7 million BTU of gas. If 63 million BTU of gas was burned in a generator at 12.2% electric efficiency and 95% overall efficiency, it would make 7.68 million BTU of electricity (2250 kWh) and 52.2 million BTU of space heat (what a 95%-efficient furnace would deliver from 55 million BTU of gas). This would both heat and power the house on about 15% less fuel. This could easily make the difference between a crisis and a yawn.
12.2% is a rather low efficiency for a generator; small diesel engines can reach 30% without undue difficulty. Suppose that the houses heated by natural gas and LPG use generators getting 25% electric efficiency (95% overall), and the ones heating with oil get 28%/95% out of theirs. These houses would burn some extra fuel but generate large excesses of electricity. This electricity could run electric vehicles (displacing motor fuel and making it available for home-heating oil), heat pumps (cutting total fuel demand further), or go for other purposes.
A cogenerator running at 30% electric efficiency and 95% overall efficiency would burn about 46% more fuel than a furnace for the same amount of heat, but it would have an electric output of 46% of its heat output. If this electricity ran a heat pump with a typical 3:1 coefficient of performance (3 BTU of heat out for each BTU of electricity in), the total heat available from the fuel would be 238% as much as the original demand (100% from the cogenerator and 138% from the heat pump). The net heating efficiency would be 155% (65% cogenerator, 30%*3 = 90% heat pump), squeezing 63% more heat out of each unit of fuel. Again, this is enough to turn a fuel crisis into a yawn.
It's gotten warm in Michigan this past week, but people are either looking at their heating bills from the previous cold snap or are waiting in uneasy anticipation thereof. The US chemical and fertilizer industries are dying because of sky-high natural gas prices. Cogeneration could have made things a lot better. Our current situation is entirely due to our own refusal to be ready for the future that's coming at us - ready or not.
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