theWatt Podcast 74

Submitted by ben on Sun, 03/02/2008 - 23:22.

download:

tWP74: The Zero-Carbon Car (30MB, 1.5hrs)

Bill Kemp is on the show discussing his new book "The Zero-Carbon Car" - a plug-in biodiesel hybrid car which he built. We talk about personal transportation issues and how he built his car.

Some show notes:

AzText Press - publisher of The Zero Carbon Car
Zero Carbon Car details:
Range:
Electricity: 12.4 miles to 80% depth of discharge
Energy Consumption: 387 Wh per mile
Biodiesel: ~ 990 miles per tank
Consumption: 0.058 gallons per kWh
Google Plug-In Hybrid Program
Previous podcasts featuring Bill Kemp: tWP63 (off-grid living), tWP60 (biodiesel)

A quick note on hydrogen

Submitted by ben on Tue, 03/04/2008 - 03:44.

I just have to make a comment on what Bill said about hydrogen at the 9min 39sec mark:

a hydrogen powered vehicle that is powered by hydrogen that comes from natural gas which, is where 99% of the hydrogen comes from on earth now, actually produces about 6-8 times more CO2 than does burning gasoline in a regular vehicle now

By my calculations, this isn't true.

To make 1kg of hydrogen from natural gas by steam reforming produces roughly 5.5kg CO2:

(2kg) CH4 + (4.5kg) 2H2O <=> (1kg) 4H2 + (5.5kg) CO2

The fuel efficiency of a hydrogen car is hard to come by but from this review of the Honda FCX, the hydrogen fuel cell car goes 190 miles on 3.8kg hydrogen. The target efficiency set by the Department of Energy for a hydrogen fuel cell car is roughly 300 miles per 5kg H2. This means that to drive 300miles in the Honda FCX today using hydrogen produced from natural gas steam reforming will emit 32kg of CO2, worst case. With the DOE target efficiency, a hydrogen car with hydrogen produced from natural gas would produce 28 kg CO2.

Gasoline has a CO2 content of 8.9kg CO2/gallon. So, let's just say we have a car that has a fuel efficiency of 30 miles per gallon. Then the total CO2 produced by that 30mpg car driving 300 miles is 89kg CO2 (2.8 times higher than hydrogen fuel cell car today). In order for a gasoline powered car to produce the same amount of CO2 as a hydrogen fuel cell car, the gasoline car must have a fuel efficiency of 83 miles per gallon.

Note that in this analysis, for both hydrogen and gasoline cars, I only considered tank-wheel CO2 emissions, not well to wheel which would make both cases look slightly worse.

So, in conclusion, a fuel cell car today powered by hydrogen from natural gas will produce less CO2 than your most efficient car available today. I'll make this the topic of an upcoming column. Battery cars are more efficient than hydrogen fuel cell cars though and the future must be efficient.

reply
link

Re: theWatt Podcast 74

Submitted by SoCalBen on Sat, 03/08/2008 - 07:45.

after listening to this weeks pod cast few comments about the tesla, each one of the 6000 plus batteries has the form factor of a AA battery, they have a dog and pony show the general pubic can go on if ya show up at their office in San Carlos, CA.

Asked some of the engineers when I took a tour last year, and they mentioned that monitoring the status of the batteries was akin to the same kind of engineering needed to monitor the batteries of a lap top (just scaled up), the big teething problem with the tesla from what I gathered is the transmission (making sure it works for the long haul).