9 months ago
Friday, October 7, 2011
It takes a lot of coal to make gasoline
BP Oil refinery in Long Beach California
Quick draw critics of the electric car often (miss their target) criticize EV’s because in their words “Electric cars simply replace a tail pipe with a smokestack” The gist of their argument is that the emissions still occur, not at the tail pipe but at the electric power plant. That great observation is usually followed by the statement that 45% of our grid electricity is coal and coal is dirty thus the EV provides no net gain.
The critics may want to look in the mirror…..or in their garage.
In California, refineries are the second largest users of electricity. Moving water around the state via water authorities is the single largest user of electricity. You guessed it, refining crude also takes a tremendous amount of water!
It is a simple fact that just the refining of gasoline requires approximately 6 kwh of electricity per gallon of gasoline. In fact electricity and natural gas cost are estimated to be 43% of the US oil refineries total expenses. If you tack on the energy required to extract and transport the oil to the refinery and then to the gas stations as well as the energy cost of the gas station, I’m sure that number jumps a few more kwh per gallon.
So let’s be conservative and cut the oil guys a break and say it takes 8kwh to extract, ship, refine and transport each gallon of gas.
What’s good for the goose is good for the gander. Drum roll…….
It takes more electricity to drive the average gasoline car 100 miles, than it does to drive an electric car 100 miles. A gas car at the US fleet average of 21mpg will consume approximately five gallons of gasoline which took 40kwh (5 times 8)of electricity to make, to drive 100 miles. An electric car will use approximately 30 kwh of electricity (3.3 miles per kwh) to drive the same 100 miles.
Gas cars use more electricity than EV’s, thus polluting at the smokestack, They burn that refined gasoline in a very inefficient engine, thus polluting at the tailpipe. In our large urban cities in the US, the emissions caused by our transportation fleet accounts for 70% or greater of our man made emissions and visible particulate matter (smog) and related health care cost. Think of that as smoking two packs of cigs.
Electric cars run on electricity created by a mixture of energy sources. Many electric car drivers like myself quickly discover that making your own via solar PV is the best and cheapest way to fuel (about $0.40 per gallon of gas equivalent) Think of that cleaning up the air in our major cities, saving money and as not smoking,
Mini-E #183, 33,000 solar powered miles
Source material below.
The United States uses more petroleum than any other energy source. Petroleum provides the U.S. with about 37 percent of the energy we use each year. Petroleum can’t be used as it comes out of the ground. It must be refined before it can be used.
Oil refineries use a lot of energy to convert crude oil into gasoline, diesel fuel, heating oil, chemicals, and other products. Almost half of a refinery’s operating costs (43 percent) is for energy. (US Energy Information Administration)
In a 2008 report, Argonne National Lab estimated that the efficiency for producing gasoline of an “average” U.S. petroleum refinery is between 84% and 88% (Wang, 2008), and Oak Ridge National Lab reports that the net energy content of oil is approximately 132,000 Btu per gallon (Davis, 2009). It is commonly known that a barrel of crude oil generate approximately 45 gallons of refined product (refer to NAS, 2009, Table 3-4 for a publication stating so). Thus, using an 85% refinery efficiency and the aforementioned conversion factors, it can be estimated that about 21,000 Btu—the equivalent of 6 kWh—of energy are used per gallon of gasoline refined:
The documents referenced are as follows:
US Energy Information Administration
Wang, M. (2008), “Estimation of Energy Efficiencies of U.S. Petroleum Refineries,” Center for Transportation Research, Argonne National Laboratory, www.transportation.anl.gov/modeling_simulation/GREET/pdfs/energy_eff_petroleum_refineries-03-08.pdf
Davis, S., Susan W. Diegel, and Robert G. Boundy (2009), Transportation Energy Data Book, edition 28, National Transportation Research Center, Oak Ridge National Laboratory, cta.ornl.gov/data/
NAS (2009), Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use, The National Academies Press, www.nap.edu/openbook.php?record_id=12794&page=1