Dear Ron
Trying to keep up – time is tight:
RWL: I think we all can guess that coal is the cheapest - but can you
give some idea of price variations - especially for those involving coking.
When someone else does the coking are those pyrolysis gases used productively?
We are not sure. I have not yet seen an actual coking plant. I suspect it will
not in the smaller ones. I worry about the liquid fractions. If there is enough
it can be sold as a mineral input for making all sorts of things. This will
probably be done on a large scale. One of the power plants is being taken out
of service and converted to this purpose.
>Could one family coke for another (the idea that brought me into TLUD design
>for wood in 1995).
We need far more than that. The inputs would be about 1 million tons a year.
There is no reason for one person to make coke. It would just increase their
fuel purchases. If they got their hands on it they would burn it (raw coal).
>I'd rather do away with coal (and charcoal not put in the ground) altogether -
>but I hate to think that the coke being used in UB was made badly.]
The present stove makes coke in the early phase of the fire then burns it
immediately afterwards. The smoke is from the ignition process. The combustion
during coking is quite good. There is a lot of misunderstanding where the smoke
comes from. Most NGO’s think it comes from coal during all portions of the fire.
[RWL: In a TLUD, startup smoke doesn't seem all that horrendous, although
definitely gets better with time. If one had a TLUD with wood and/or charcoal
as the starter and a fan to provide just the right amount of air, with coal
below - intended to turn into coke for re-sale - what do you predict for
start-up and operational particulate release?
Fans are an option. At the moment there is no decent facility to determine the
emissions at all. The technology used HAS to be refuelable on a continuous
basis.
>I have no experience with BLDD, but would guess the same should prevail - with
>the added advantage you can keep it going.]
Exactly.
[RWL: I am trying to determine if BLDD and TLUD are different during
start-up. Wood and "extremely dense smoke" sure don't have to go together.
I was r eferring to a conventional ignition. A wood fire is started then coal
is placen on it. That puts out the flame for some time, basically.
>I have gathered from the comments of John Davies, that coal was always pretty
>bad until one had turned the coal to coke.
Quite incorrect. The cleanliness of the burn depends heavily on the
availability of Hydrogen in the early fire. Later, retained heat can be used to
keep the coke burning.
>My hope is that with a controllable fan, one could start the wood fires more
>readily. Even for a family without electricity, I would guess that a
>PV-powered fan/blower system would prove cost-effective.]
A chimney is a fan without power. All it requires is some imaginative stove
development. In June during training we made very clean starting side draft
stoves which are almost as good as TLUD and can be refuelled at any time.
[RWL: Below you include TLUDs in a similar list. Have they been tried and do
you believe they would have same 98% factor?
Yes. Usually better than 98% reduction but we were only able to confirm CO
because of a lack of ability to measure condensed particulates (which is most
of the problem). We were stuck with the CO as a proxy.
>I have come to believe that the radically different World Stove design
>(sometime called TLOD) is the cleanest of them all. If Nathaniel is listening
>- have you ever tried coal? ]
It may or may not work. I have not seen one that could hold 8-10 kg of coal.
Coal going in is cold and that is a major issue. Then it gives off huge amounts
of volatiles if it is heated rapidly. Then the characteristics of the fuel
composition change dramatically. It is unlikely that a heated batch will be
manageable. The sidedraft stoves overcome all these problems.
[RWL: Not being familiar with this term, I found something at:
http://www.dme.gov.za/pdfs/energy/coal/basa_njengo_tembisa.pdf
and
http://cef.org.za.www29b.your-server.co.za/index.php?view=article&id=40%3Arollout-of-the-basa-njengo-magogo-programme&option=com_content&Itemid=17
It sure sounds like a TLUD to me (BLDD for you).
It is TLUD. The SeTAR Centre has been testing and quantifying emissions for the
technique. It is likely to be over a 90% reduction compared with bottom
lighting (BLUD). It turns out the air holes in the 25 litre tin have a large
effect on combustion quality. We found really bad ones!!
I wonder if any of these folks are controlling primary air as well? It look
slike they haven't learned about secondary air and chimney effect yet.
They use the number of holes for air control. There is a temporary chimney used
during ignition. Secondary air is provided by a set of holes above the grate so
I guess the answer is ‘Yes’.
[RWL: I hope we can have a response from such a stove exhaust system
installer. I don't think they have a problem with draw. They use ceramic
rather than metal "piping" - and I don't believe they have corrosion problems.
OK. Well…..think a total system cost of $50.
[RWL: Then, I gather that the whole concept of energy efficiency and
passive solar is being scrapped for lack of a small stove? Weird reasoning.
Obviously not. Solar was promoted and it is expensive. People earn about $250 a
year. People already have stoves when they pull into town on their yak carts.
Straw bale houses have been promoted and they work quite well. The programme
may have been mismanaged and the technology given a bad name. It is a dead duck
now.
[ RWL: Still wondering about the number of stoves - sounds like it might
be about 100k?
It is about 150,000. If someone wants to rock up and start promoting a stove
please investigate the years of disaster caused by people doing exactly that.
Investigate the cooking demands and the heating cycle, the fuels available and
done mess with market. It is grim reading.
>The Chinese (relatively nearby) have installed I think 70% of all the solar
>hot water systems in the world.
Water heating is not a big need compared with keeping the cold out of the tent
at -35 C.
>I see that Mongolia gets its rain in the summer - so Ulaan Baatar (world's
>coldest capital) might be world's best place for solar heating.
Not if you can’t see 100 metres through the thick coal smoke! Little light
reaches the ground in many places in Nov-Dec.
Regards
Crispin
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