Regarding Brahama D. Sharma's letter (June 2-9), "Biodiesel still requires combustion":

Yes, it does. And so do almost all forms of vehicle transportation, excepting an electric car plugged into an all-solar home, or perhaps nuclear power. Mr. Sharma fails to note that while burning biodiesel does produce carbon emissions, the carbon produced is contained within a closed circle. That is, biodiesel is made from plant-based oils. These plants, as do all plants, absorb CO2 as a part of their energy cycle. When the oil is burned, the CO2 released is equal to the CO2 that is used by a growing crop of plants to be used for production of the same amount of biodiesel. Nothing left over. Petroleum takes millions of years to turn plants into a usable, carbon-based fuel source. When burned, this carbon would take millions of years to return to being a plant-based petroleum source. This circle takes too long to get back to its starting point, hence the rising levels of CO2 present today.

Biodiesel can be produced locally, it is nontoxic, it provides a true, valuable market for crops that traditionally have been heavily subsidized, and it literally cleans one's engine. That is not to say that biodiesel answers all our energy problems; far from it. We could all do a lot by the three R's: reducing, reusing, recycling, and, while biodiesel fits well into this idea, petroleum never will. Yes, biodiesel fuels egos too, and it's okay to feel good about doing something that makes a measurable, smellable, difference.

Josh Laufer

Los Osos