Microwave Pyrolysis Claims Challenged
UK-based Carbonscape and its founder Chris Turney were recently profiled in the Guardian UK regarding its nascent “Black Phantom” microwave pyrolyzer. Based on limited information, it appears the Black Phantom uses heat from microwaves to dry and eventually pyrolyze wood and other biomass. According to the article:
Turney’s idea to use a microwave, which he found could lock away up to 50% of the wood’s mass, came from a cooking accident when he was a teenager, in which he mistakenly microwaved a potato for 40 minutes and found that the vegetable had turned into charcoal.
The article goes on to state that Carbonscape can produce biochar for $65/ton in the UK, making the technology economically viable under a carbon credit scheme.
However, some have questioned the accuracy of these claims. Members of the Biochar Listserv have noted that an average microwave is typically only 64% efficient, compared to an electric heater which is generally 100% efficient at converting electricity to heat. Furthermore, list members have noted that Carbonscape is not clear on whether they have taken into account the carbon footprint (and cost) of powering such a large microwave. We support innovation in the low-cost pyrolyzer technology space, and hope that Carbonscape will answer these very valid concerns.
Graham Knight
April 9th, 2009 at 4:19 am
Although I share the doubts of many that microwaving can be viable for making biochar I must correct an erroneous statement above.
While it may be true that, “…an average microwave is typically only 64% efficient, compared to an electric heater which is generally 100% efficient at converting electricity to heat”, that is not a fair comparison.
The energy of a microwave is concentrated inside the vessel while heat placed under a vessel (or your saucepan) is mostly lost!
But the original energy usually comes from a fossil fuel and has lost 70% of its energy on the way – as electricity.