Also keep in mind that, whatever carbon waste source we would use to feed algae whether it is CO2 from dirty fossil fuel plants, or Methane from animal agriculture, what we would essentially be doing is only temporarily absorbing carbon that is being unnecessarily produced in the first place, (when we should instead be using true renewables, and eating much more vegetarian oriented diets in order to -not- generate that excess carbon). We would only be temporarily taking unnecessary waste carbon, turning it into algae, processing the algae into fuel, and then releasing that very same excess carbon into the atmosphere anyway, when we burn the algae fuel. This is absurd. All it does is delay the release of the pollution by storing it a bunch of algae for a while... Even in the case of methane from waste dumps, we need to reduce the capacity of the dump to produce so much methane in the first place, and whatever methane is left after this reduction, figure out the best way to split it into hydrogen in order to keep -that- carbon source -out- of the atmosphere, instead of just temporarily processing it through the tiny bodies of algae, only to later release it again as biofuel carbon combustion waste. Combustion fuel, no matter its source, must go. Algae is not an answer. And to speak to an earlier point, we need to stop flying around in airplanes and develop very high speed ground trains instead. There is no reason renewable electric powered mag lev trains can't get us around just as quickly, or even more quickly, than airplanes. cheers Eric