Sunday, August 16, 2015

Carbon free renewable energy…revisited...

The Intergovernmental Panel on Climate Change (IPCC) now says we must actively remove carbon from the atmosphere to mitigate the full climate effects of the carbon we've already put out. In other words, there's enough carbon in the air now to warm the planet from 2.5 to 8 degrees Fahrenheit. To not exceed those temperatures, we must have a net carbon emission of zero. To mitigate the damage of those temperatures, we must pull carbon out of the air.

I had previously suggested that offshore energy collectors (any combination of solar/ wind/ wave collectors) could generate hydrogen by electrolysis from sea water. But Elon Musk has said hydrogen is a terrible and inefficient way to store energy. Taking him at his word (knowing very little about the topic), this means we need a better storage mechanism for our putative offshore energy collectors... and it happens that the US Navy has developed a way to synthesize hydrocarbons from carbon in sea water. This means it might be possible to convert the energy collected by floating ocean based energy collectors into hydrocarbon fuels for use on land. Because the ocean is such an efficient carbon sink, this would be a very good indirect method to extract carbon from the atmosphere.

To be clear: synthetic hydrocarbon fuels are net neutral in terms of atmospheric carbon because they release carbon back into the air when used. To get a net negative atmospheric carbon reduction, carbon needs to be sequestered in biomass (grow lots of vegetation in native ecosystems).

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