Monday, May 18, 2009

Real Energy Numbers For a Change

Here are a few basic energy numbers from David MacKay. As the importance of moving away from dictator-controlled energy grows more apparent, we will need to pay more attention to the underlying numerical comparisons between various energy loads and energy supplies. We will need to become more literate in the mathematics of energy.
One kilowatt-hour (kWh) is the energy used by leaving a 40-watt bulb on for 24 hours. The chemical energy in the food we eat to stay alive amounts to about 3 kWh per day. Taking one hot bath uses about 5 kWh of heat. Driving an average European car 100 kilometers (roughly 62 miles) uses 80 kWh of fuel....

To supply 42 kWh per day per person from solar power requires roughly 80 square meters per person of solar panels.

To deliver 42 kWh per day per person from wind for everyone in the United States would require wind farms with a total area roughly equal to the area of California, a 200-fold increase in United States wind power.

To get 42 kWh per day per person from nuclear power would require 525 one-gigawatt nuclear power stations, a roughly five-fold increase over today's levels....

Most prototype hydrogen-powered vehicles use more energy than the fossil-fuel vehicles they replace. The BMW Hydrogen 7, for example, uses 254 kWh per 100 km, but the average fossil car in Europe uses 80 kWh per 100 km.

.....The problem with hydrogen is that both the creation and the use of hydrogen are energy-inefficient steps. Adopting hydrogen as a transport fuel would increase our energy demand. And, as I hope the numbers above have shown, supplying energy to match our demand is not going to be easy. _CNN
H/T Ron Rupper

For a genuine education in the numbers of energy, go to David MacKay's website.



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