Tuesday, December 27, 2011

Energy Density of Automotive Fuels: Electricity Trails Badly

Exxon Mobil via New Energy and Fuel

The most striking thing about the graphic above is the poor performance by today's automotive electrical storage devices. Liquid fuels far outperform electrical storage in terms of energy density -- range of travel between refuelings. Until better electrical storage devices are developed and delivered -- which may take decades -- liquid fuels will be demanded by discriminating drivers.
...contrast the 300 to 400 miles that a gasoline vehicle can take you with what it would take to do the same in an electric vehicle. Electric vehicle batteries have just a fraction of the energy density of gasoline, meaning they would have to be charged multiple times during a 400-mile trip. There’s currently no major infrastructure for charging electric vehicles on the road, and it can take hours for an electric vehicle battery to charge.

Consumers at times may take for granted the convenience and time-savings offered by the existing fuel station network. The technological processes that recover crude oil from the earth, transport it to refineries, refine it into gasoline and diesel, transport it to fuel stations and store it over time are so incredibly advanced that consumers can fill up with gasoline 24 hours a day, seven days a week, in as many quantities as necessary. That’s a convenience that does not currently exist with other transportation fuels.

...One of our top scientists uses the analogy of backpacking when talking about the importance of energy density: You want to buy the lightest, most easily carried food for backpacking, but it also needs to contain a lot of energy to keep you going. Likewise, gasoline and diesel are the lightest and most energy-dense fuels to carry for transportation. A typical car’s gasoline tank contains less than 100 pounds of gasoline but can power a 3,000 pound car for 400 miles at 60 miles per hour. This performance sets a high standard, and there are few transportation fuels currently on the market that are as light, energy dense and portable as gasoline or diesel. _EMblog via Brian Westenhaus

In the future, the development of lightweight advanced fuel cells running on liquid fuels will shift the equation toward the use of electric motors. But liquid fuels will still be valued for their high energy density, compared to electrical storage.

Super-hybrid vehicles utilising fuel cells, supercapacitors, and chemical storage batteries are likely to play a part in the future vehicular mix. All of those components will be necessary just to match the performance of the internal combustion engine running on liquid fuels.

But with far fewer moving mechanical parts, once such systems are perfected they should have fewer maintenance problems, and may have longer useful lifetimes.

Labels: ,


Post a Comment

Subscribe to Post Comments [Atom]

<< Home

Newer Posts Older Posts