The Azimuth Project
Carbon negative energy (Rev #3, changes)

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Carbon negative energy refers to any form of usable energy whose production reduces the amount of carbon dioxide in the Earth’s atmosphere.

Biochar Biofuel versus biochar

One Photosynthesis source can take carbon out of the atmosphere and provide useful fuel. If all the carbon negative taken energy out is returned to the atmosphere when this fuel is burnt, this process is roughly carbon-neutral. This is an oversimplification of the actual story. On the one hand, it takes energy to grow and process vegetation into usable fuel; if this energy comes from fossil fuels there may be a net gain of CObiochar2 : in the creation atmosphere. of On gas the from other wood, hand, leaving not behind all charcoal the which carbon can is be returned buried to sequester the carbon. atmosphere: some stays in the ground, at least for a while, in the form of roots, humus, etcetera.

We need detailed figures here! What is the overall carbon footprint of biofuels? People have done research on this already, and the results should probably go in a page on biofuel. — John Baez

Ignoring these subtleties, we may very roughly say that fossil fuels are carbon-positive while biofuels are, at best, approximately carbon-neutral. On the other hand, biochar offers the possibility of strongly carbon-negative energy production: significant long-term reduction in atmospheric CO2 combined with the production of significant amounts of energy. The idea here is to create some usable fuel from plant material, while also creating large amounts of charcoal which can be buried to sequester carbon. Unlike rotting vegetable matter, buried charcoal can sequester carbon for centuries or even millennia.

For more, see biochar.

If you can think of other sources of carbon negative energy, enter information about them here! — John Baez


Inasmuch as you can eat sugar, or presumably build a fuel cell to run on it, photosynthesis is one of the oldest carbon-neutral to carbon-negative energy production/storage methods in widespread use today. According to the fossil fuel hypothesis?, even petroleum- and coal-burning processes are powered by ancient deposits of photosynthetically-fixed carbon. More recently, it is also the primary source of raw materials for biochar energy production.

I suppose that may look annoyingly … something. One-up-you-ish? I think it’s good to remember, anyways. — Jesse McKeown