Sample Calculation for a High School Course on Sustainability
Cost of Wind Energy for 10% of US Energy Consumption
We calculate on the basis of 10% of US consumption because that is high enough to be very useful and low enough that we could possibly achieve it. One hundred quads production is almost certainly unachievable.
Currently the US is using about 100 quadrillion btus of energy (quads) every year so 10 quads=10%. We must use a conversion factor to convert btus to kwhrs. Since it takes about 10,000 btus of fossil energy to create one kwhr, 10,000 btus=one kwhr is the best conversion factor. To convert 10% of US consumption to kwhrs we divide 10*10^15 (ten quads) by 10,000 to get10^12 kwhrs(one trillion) needed for 10% of US total energy consumption.
Recent figures about new windfarms say 48 Million cost for 30 megawatts peak output. This gives us a cost figure of $1.6 per peak watt. In order to get total cost for producing 10% of US consumption we must know what percentage of the time the wind is blowing. This can vary from 20% to 60%. We chose 40% as the most common.
The hours in one year are 365* 24= 8760. In a year's time, one peak watt produces 8760* .4 =3504 watt hrs= or 3.504 kwhrs. Then the cost for 10% of US energy using wind=(1*10^12)/3.504=$456 billion up front investment capital. Since this is a very approximate calculation you might as well say that it takes $.5 trillion in investment in wind energy to supply 10% of US consumption.
This result shows how great the energy problem is. It shows the stupid inadequacy of George Bush's $5 billion fund for hydrogen, or Senator Liebermans "$25 billion to free us from foreign oil." Wind energy, unlike solar, is almost cost effective. It is the likeliest form of alternate energy, yet the investment costs are high.
I am not telling you not to build windmills. I am trying to tell you how formidable the job is. The children must learn about this problem and how to cope with it. We must spend the money on alternate energy or our children will die. We can reduce energy consumption by about 70% by building big energy saving apartments. That will cost at least $15 trillion. Then we must spend about $5 trillion on wind, solar, and biomass to avert a national catastrophe. We must do this for the children.
Kermit Schlansker PE