When I was looking for options to offset our airmiles I noted and commented on a significant difference between the carbon production estimates, and the cost to offset it, from NativeEnergy and Carbonfund.org.
I remarked on this in the comments box when placing my order with NativeEnergy and today received the following response from Lauren Aldrich at NativeEnergy, which she has said I’m welcome to post here:
Thank you for asking about the CO2 emissions and price discrepancies between NativeEnergy and Carbonfund. It’s important to us that our customers understand why these differences exist, because there are good reasons.
Regarding CO2 emissions from air travel: Carbonfund assumes a conservative emissions scenario, using a rate of 0.6393 lbs of CO2 per passenger mile. This industry-accepted rate describes the emissions caused by ‘short haul’ flights – flights up to 281 miles long – that are energy intensive because of the amount of altitude gained compared to the cross-country distance. NativeEnergy allows customers to place their flight mileage into the ‘short haul’, ‘medium haul’, or ‘long haul’ categories. It seems that you placed your miles in the ‘long haul’ category – for flights greater than 994 mi long – and our calculator applied the correct emissions factor of 0.3903 lbs of CO2 per passenger mile. Long distance travel is less energy intensive per mile than short haul travel. This explains why your NativeEnergy travel footprint was almost half of what Carbonfund calculated. (Note also that Carbonfund footprints are given in metric tons, while NativeEnergy uses short tons. 1 metric ton = 1.1023 short tons).
Regarding the price difference: Carbonfund buys low-cost offsets from existing renewable energy projects and from the Chicago Climate Exchange, a carbon trading super-market. On occasion we purchase offsets from existing projects, and offer them at rates comparable to and often lower than Carbonfund. In the normal course, however, we choose what we and our customers believe are much higher value offsets, for which we pay a much higher price, and so must charge a higher price. So when you buy offsets from NativeEnergy, you do pay more, but you also get more — instead of just subsidizing existing projects owned and operated by large corporations, you get to help a Native American tribe or a family farm to build a truly new renewable energy project, creating environmental benefits while helping build sustainable economies in communities in need. We are proud that our customers value the difference.
I hope I have answered your questions sufficiently, and again, thanks for asking.