

Five Energy Technologies with big potential - brkumar
http://online.wsj.com/article/SB10001424052748703746604574461342682276898.html

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envitar
RE: Five Technologies That Could Change Everything Monday, October 19, 2009
7:09 PM From: "Totty, Michael" <Michael.Totty@wsj.com> To: envitar

Sir,

Thanks for your note. Space limitations prevented me from mentioning Tesla,
which indeed gets considerably more miles on a charge than a Volt. As I
understand it, it does this by using some sophisticated electronic controls
and a huge array of batteries, both of which help account for the Tesla
roadster’s steep price tag. The point I should have made more clearly is that,
when cost and weight are considered, lithium-ion batteries in production
vehicles are going to continue have a much smaller range than comparable
gasoline-powered vehicles. Not to suggest that makes them impractical – some
80% of all car trips are less than the Volt’s 40 mile range. But the grail
remains something with even a higher power density than lithium ion.

You’re also correct about flywheels – they’re useful for a number of critical
grid applications, mainly in maintaining power during brief outages. Most of
the experts I talked with, though, didn’t include them as a solution for
larger storage needs, or to handle storage for variable power sources like
wind. Still, there’s a lot of interest in flywheels, and they probably merit a
closer look in the reports.

I appreciate your writing.

Best regards,

Michael

Michael Totty

News editor/Journal Reports

The Wall Street Journal

