[Stoves] News: Methanol cooking fuel for india...

[Crispin Pemberton-Pigott]

Dear Nikhil

1. Do efficiency and CO emission rates vary with power, given a particular stove and alcohol or for that matter any fuel?

Yes, and it is important that a standard seeking to protect consumers has to require the stove be tested across a range of power, and it is likewise necessary to include tests at different altitudes of the country (supposing it is a national standard) where there is a difference of say, 3000 ft.  Non-pressurised stoves are far more impacted by altitude than pressure stoves. Think: kerosene wick stoves and pressure stoves.

I can generalise and say that most ethanol stoves are very clean-burning at low power and not good at high power due to poor air-fuel mixing. In the case of one stove I have seen that was optimised to pass a national standard that only tested at high power, it was very good for CO at full blast, but if turned down, it was pretty dreadful. It would have failed a test with a 2% CO/CO2 ratio below half-power if that was included in the test sequence.

2. With a ventilated environment or outdoor cooking, do CO emission rates from stoves risk high enough dose to cause headaches, fainting, or death?

No, I believe they would not, depending on what you mean by “ventilated”.  The problem is, because of all the claims that some “fuels are clean” people take that at the word of the claimant and assume they can use it in a closed kitchen, keeping out the weather, for example.  After all, if it is a “clean fuel”, then logically it must be safe to burn indoors.  It is false advertising with potentially deadly consequences.  If that happens, they should sue those responsible for making the claim about the fuel being “clean”.

>What plays in Stuttgart and Serengeti might be entirely different things. Many poor people use fuels and stoves “beyond design basis”.

Correct. If these fuels were not advertised as “clean” the risk would be diminished.

>That limits the reach of better stove design and “scientific” lab testing.

That is I think, an overgeneralisation. If an ethanol or methanol stove burns properly across altitudes and power settings, then it is safe enough to be used indoors, in the same way people live indoors with all the doors and windows shut.  Homes have to have a certain air turnover to be safe. Having another person in the home does not make it dangerous. If a stove is very clean it is no different from having a few visitors.

>Hence the practicality of “clean fuels.”

Well, the practicality is for clean stove+fuel+operating conditions it results in low emissions.

>Dumb doesn’t necessarily mean stupid.

Quite.

Crispin
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