Hmm could be that the way is co2->algea->hydrocarbon->H2 and carbon as a byproduct. Still I dont think its Carbon negativ because they rather make hydrocarbons

Hmm could be that the way is co2->algea->hydrocarbon->H2 and carbon as a byproduct. Still I dont think its Carbon negativ because they rather make hydrocarbons out of it and the production uses energy plus. Only wanted to state the possibility of Carbon negativ as real.