Pickin’ on the plan

Pickens’ natural gas plan makes no sense and will never happen

…So Pickens proposes to divert 6,869,624 million ft3 of NG (about 20 percent of NG usage in the U.S.) from generating electricity, and use it for transportation. In place of those NG power plants, Pickens proposes that we build wind turbines sufficient to generate at least 813 TWh/year. I say at least that much wind, because it is difficult for wind to substitute for NG electricity. NG power plants are often used to fill in gaps between supply and demand on the grid. Such “peakers” must quickly turn on and generate power whenever there is a mismatch. Wind on the other hand generates based upon weather, not the directives of grid engineers. Pickens does not spell out on his webpage how this mismatch is to be rectified. Nonetheless, let us proceed with a simple 813 TWh/year of wind.


We now compare how much of U.S. passenger vehicle travel can be powered by 813 TWh of electricity and by 6,869,624 million ft3 of NG. To estimate the latter, go to fueleconomy.org and click on first 2008, then Honda, then Civic CNG. You see 28 mpg, and a footnote:

Compressed Natural Gas (CNG) is normally dispensed in “equivalent gallons” where one “equivalent gallon” is equals to 121.5 cubic feet of CNG. The fuel economy for natural gas vehicles is shown in miles per gallon-equivalent.

So dividing 28 by 121.5 you get 0.23 miles per ft3. So if you take the Table ES1 NG quantity, and multiply by 0.23 you get 1,588 trillion miles. That is 57 percent of the 2.76 trillion passenger vehicle miles traveled in the U.S. in 2005. This is only for vehicles as small and aerodynamic as a Honda Civic; a smaller percentage of the U.S. fleet could be powered by CNG. The rest would be presumably powered by gasoline under the Pickens Plan.

Now let’s estimate miles that could be powered by electricity. A Lithium-Ion EV the size of the Honda Civic CNG should require at most 250 Watt hours per mile (Wh/mi) at the garage plug, probably less. At the power plant that is 270 Wh/mi. So take the 813 TWh, divide by 270 Wh/mi, and you get 3.01 trillion miles, which is 109 percent of the 2.76 trillion miles driven in the U.S. in 2005.

Which would you choose, 57 percent or 109 percent? It seems pretty straightforward that electric vehicles beat CNG vehicles almost 2:1, even using existing NG power plants. If the U.S. upgraded its NG power plants to be 60 percent efficient, instead of 39 percent efficient, we would have 54 percent more TWh, or even better, use less 35 percent less NG.

Grist