How do plants compare to solar cells when it comes to collecting solar energy?
This is a hard question to answer exactly because there are a lot of variables. However, here is one way to think about it: If you were to use an acre of ground to raise corn, and you then turned that corn into ethanol (alcohol), you could get a measurement of the energy that an acre of plants can capture from the sun. Then you compare that number with solar cells. In the United States, a typical acre of ground can produce about 100 bushels of corn. One bushel of corn can produce about 2.5 gallons (9.5 liters) of ethanol. A gallon of ethanol can produce about 80,000 Btu (British thermal units) of energy. According to How Horsepower Works, it takes 3.41 Btu to create 1 watt-hour of electricity. Putting all of this together, you can see that an acre of corn can produce 58.6-million watt-hours of energy. [Note that we are ignoring dozens of details to arrive at this number. For example, we are ignoring the energy cost to plow the land, produce the fertilizer a
