been posted somewhere :

Some algae species has the capability to photosynthesis in a higher-rate  than any other plants in the world. It means that when these algae  photosynthesizing, they can turn much more CO2 into Hydrocarbon chain  that store solar energy, which would be harvested later as Biofuel.

The  idea is to create a small, rugged compartment to grow algae that is  compact enough to be attached into a motorcycle. This component is  called the Photo-Bioreactor. It looks like a clear tube contained water ,  algae and some nutrient.

Supplied with CO2 and sunlight, these  algae will grow and produced oxygen within the Photo-Bioreactor. The CO2  needed for the process will be supplied by the motorcycle's engine  exhaust. When the Photo-Bioreactor has enough Algae concentration, the  motorcycle owner could bring it to a biofuel producer to get "fresh"  Photo-Bioreactor as an exchange. "Fresh" Photo-Bioreactor means, a  Photo-Bioreactor with low algae concentration and more nutrient.

With  this technology, motorcycles would become carbon-neutral vehicle  because the CO2 produced by the engine's combustion are turned into O2  by the Algae's photosynthesis, and the biofuel producer got raw material  to process. So we will get double benefits: clean air and carbon neutral fuel.

Things still unclear is the effect of compartment to engine performance.