Friday, March 7, 2008

Another article about my PHEV/EV and water usage - unneccesarily alarmist

Another article, this time in New Scientist, has been written about my paper on "water of the plugged-in automotive economy". See a recent post on water used while driving on electric miles for my basic take on how to interpret the analysis.

Phil McKenna, the journalist and writer of the article, chose the title " 'Thirsty' electric cars threaten water resources". This is an unfortunately alarmist title. The article prompted some to blog on the New Scientist page that I was against plug-in hybrid electric vehicles (PHEV) or electric vehicles (EV). This is certainly not true. Some suggested I must be paid or work for some petroleum or natural gas company. This is also certainly not true.

I gave Phil information to present the scope and scale of electric driving upon the electricity grid and water resources, but he didn't mention this.

For example:
1 million PHEV40s (PHEVs that have a 40 mile range) would drive about 7.3 billion miles per year. This is about 0.3% of miles driven by light duty vehicles.

The resulting water consumption is 1.7 billion gallons, or ONLY 0.13% of water consumption already associated with power generation.

The resulting water withdrawal is 76 billion gallons, or ONLY 0.11% of water withdrawal already associated with power generation.

I, and my coauthor, chose to independently look at link between energy and water. This work is a first foray into this area, and we have also analyzed other fuels (biofuels, hydrogen, coal to liquids, etc.) that is in the review process for publishing.

So ... NO ALARM. We have time to plan for 10s of millions of PHEVs, let's get them on the road!


James Philippi said...

I've driven a PHEV for over a year. I get over 100mpg using Clean Domestic Wind Energy to offset the amount of Dirty Foreign Oil I use. On water is used to produce the electricity I put into my car.
I do have a question though, how many gallons of gas, and other energy, does it take to, locate, extract, ship, process, refine, transport, deliver, and pump just one gallon of gas to my car? I really would like to know because saving over $400 per month not buying all the gas I use to buy is not even the half of it.

James Philippi
Houston, TX
PHEV Owner and Driver

Carey King said...


Good question. The GREET model run by Argonne National Lab ( is basically for this purpose. The model calculates energy and emissions required over the operational life cycle of the vehicle. It is the most glorified Excel spreadsheet I've ever seen, but now has a GUI interface too.

See the GREET list of publications ( but in particular, this one ( is a pretty good starter document.

It shows many fuels and vehicles (including EVs) and how they compare on energy (Btu/mile) and emissions (per mile). See how EVs charged on the US grid consume about 3000 Btu/mile compared to a regular internal combustion engine on reformulated gasoline (it is a CA study) at abotu 5,200 Btu/mile. This example shows that only 58% as much energy is required for an EV over a gasoline vehicle.

Notice how this document assumes the US electricity mix, and how wind and PV solar can take the emissions practically to zero.

Thanks for the inquiry.