$49.95 to offset 20,000 lbs of Co2 soulds like a bargin to me.

What are the CO2 outputs of various vehicles ie hybrid, mini-van ave car ave light truck etc.

What is the resulting lbs CO2 reduction per $ of vehcile A vs vehicle B if either vehicle can perform the required tasks.

ie a 2 seater insite is not a sutiable replacement for a 15 passenger van if you need to move more than 2 people, but diesel van could take the place of a gasoline modle.

Likewise a hybrid car could replace a non-hybrid modle provided they have the same seating capacity, if towing capacity, or 0-60 performance is a requirement that too would be a consideration.

So out of this...
Can you get the same or C02 reduction per $ spent as you would buying a hybrid / vehicle A by buying vehicle B and purchasing C02 credits to make up the difference between the two vehicles?

It will be a while before there is enough ethenol or biodiesel to justify making all their engines capable of running on them.

Oh, I get it. The dollars you spend on the Terrapass provides the extra mile to make the projects viable. Your dollars aren't really saving all that carbon your car admits, but, theoretically, they are making a marginal project possible so that the whole project will offset your car's emissions.

I bought a Terrapass, but I remain just a bit skeptical.

To be safe, I would buy the most efficient car I could find, drive as little as possible and buy a Terrapass.

After all, we really need to cut our carbon emissions by 75% to even come close to eventually slowing down global warming.

I'm loaded up with shares in alternative energy companies, but the stock market is a secondary market, so I think that's only helping indirectly.

Kyle,

there are still concerns about the net energy output of ethanoland the practicality of having all of the vehicles in the US running on it. there is a nice wiki article you might enjoy.

biodiesel, on the other hand, seems like an idea solution for the US. some parts of the country may require heated fuel tanks to prevent clogged filters, though.

the processing required fomr biodiesel is much simpler than ethanol and diesel engines are inherently more efficient, so biodiesel is a naturally easier solution.

In the 15th century, the catholic church sold indulgences to finance the construction of St. Peters in Rome. Pay-as-you-sin eventually led to Martin Luther and 250 years of religious wars.

So instead of buying a gas guzzler + TerraPass, just buy a more fuel-efficient vehicle. Ford has a few models by way of its Mazda subsidiary, and will build more if there is demand for them. Other manufacturers also offer plenty of choices.

Btw, E85 and B100 in just a few cars will make their owners feel oh-so-green but have little impact on overall GHG emissions or dependence on foreign oil. Better to blend in low fractions into ALL fuel sold nationwide, this also eliminates the need for a new distribution infrastructure etc. Blending is less sexy, less individual, but on aggregate, far more effective.

The link below is to a Tech Talk given recently by a person in the know, at a place of business you might have heard of. He talks about Brazil, what it took, how they did it, why it won't work quite the same way here. What we can do to help. energy input/output balances, carbon balances, emmission issues. It will take 1 hour of your time and is quite informative. I recommend it.
http://video.google.com/videoplay?docid=-570288889128950913&pl=true&q=biofuels