F.A. Farm

  (Ferndale, Washington)
Postmodern Agriculture - Food With Full Attention
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Something Simple to Think About

There have been several comments on how much energy is in a litre of petrol since I first questioned Rob Hopkins’ comparison of 1 litre of petrol to 35 days of hard human manual labor. It is amazing to me how many people still confuse input with output. Allow me to make a few simple points.

  • It takes energy to do anything.
  • When you use energy, you generate heat and waste products.
  • An engine is regarded as efficient if it produces work output equal to 20% of its work input. This is the standard for the internal combustion engine.
  • Since the internal combustion engine only gives back 20% of the energy it consumes, 80% of the energy is wasted as heat and gases.
  • These gases go into the atmosphere. The heat does too.
  • This warms up the planet.
  • For every bit of work you are doing with an internal combustion engine, you are wasting 4 times as much energy that is going into the atmosphere.
  • A power plant produces energy equal to 30% of its input as a rule.
  • The electrical power grid has an efficiency rating of 40%, so the actual power that gets to you is only 12% of the energy you use to fire up the power plant.
  • When you use an internal combustion engine you waste 80% of the energy. When you use electric power to toast your bagel in the morning, you are wasting 88% of the energy.
  • All discussion about how the output is used to do work is irrelevant because of the GIGANTIC waste of energy when using fossil fuels as an energy source.
  • What you do with the output is your business. What you do with the 80-88% waste is everyone’s business.
  • All discussions about fitness levels and who can pedal a generator faster or for how much longer are irrelevant to the energy content of a litre of petrol.
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