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!

Water for Transportation - publication on "electric miles"

A paper of mine has been published online today in the journal Environmental Science and Technology. The paper describes how much water is used, that means consumed and withdrawn (which are two different concepts) for driving a vehicle on electricity as "fuel". This pertains to electric vehicles (EV) or plug-in hybrid electric vehicles (PHEV) while they travel on battery power alone.

First, two basic definitions:

water withdrawal is that water which is taken from a source, run through a process, and returned to the source or some other source.

water consumption is water that is withdrawn but not returned to the source due to evaporation (for example - in cooling processes for steam power plants) or evapotranspiration (evaporation from through plants).

Due to water consumed and withdrawn for cooling steam electric power plants (coal, nuclear, geothermal, solar concentrated power, and most natural gas), we can associate that water usage with the electricity generated from the plant. Assuming that an EV or PHEV is charged with electricity from the generic U.S. grid, each mile driven by a average light duty vehicle (a car, pickup truck, or SUV) will consume 0.2-0.3 gallons of water and withdraw 8 gallons of water. This is approximately 2-3X more water consumption and 12X more water withdrawal than when driving a light duty vehicle on petroleum gasoline.

Does this mean we should not pursue EV and PHEV technology? ABSOLUTELY NOT.

There are many benefits to the integration of EV/PHEV vehicles which include the ability to use a diversity of fuels sources - anything that can end up generating electricity (burning stuff to produce steam, nuclear power, wind power, photovoltaic solar, etc.). The ability to use a variety of transportation fuels by way of the electric grid is very powerful and important.

While the water consumption and withdrawal is higher than using petroleum gasoline, we can easily plan and accommodate for the increase in water usage per mile. The use of EV/PHEVs will occur gradually, and water resources will not be the limiting factor for their adoption. Full speed ahead for electric cars.

Pros and Cons of Wind Energy

Here is a link to another article in an ever increasing list of discussions about wind power and its pros and cons. More and more negative or problematic points about wind energy are surfacing, and it is mostly because wind energy is starting to have a measurable impact instead of just being 'in the noise' of the electricity generation mix.

Essentially, because utility and grid operators don't know exactly when wind power will be getting generated due to the unpredictability in wind speed, there are additional actions that need to be taken in operating a reliable electric grid. As the amount of installed wind capacity (the MegaWatts installed if all wind generators were operating at maximum power) gets to over 10% of the entire grid capacity (wind, nuclear, coal, natural gas, hydroelectric, etc.), the other electrical generators are required to operate to account for the increased wind capacity. This assumes, of course, that you are going to allow the full available wind power onto the grid at any given time.

A study by GE (see http://www.ercot.com/meetings/ros/keydocs/2007/1022/Variablity_and_Predictability_draft_dlvd_2a.zip, or link on page http://www.ercot.com/calendar/2007/10/20071022-ROSWIND.html), done for the Electric Reliability Council of Texas (ERCOT)
shows that the dispatchable generators (those that can be turned on at any time) have to be able to ramp up and down faster the more that wind is integrated into the grid. Interestingly, the predictability of the total load that needs to be served by the dispatchable generators stayed about the same as without wind. This is because there is already enough uncertainty in the electricity demand throughout the day such that the added uncertainty of wind generation was not incredibly influential.

Basically, with more wind, we are deciding how many other additional aspects (higher generation ramp rates, more transmission lines, etc.) we are willing to deal with to have a clean source of electricity. The fact that wind energy is getting questioned for its newly-perceived (though not new at all) drawbacks is a testament to the wind industry already solving many problems to become a mainstream source of electricity.