Crispin and stoves list:
Thanks - good response Few more comments added below in bold. ----- Original Message ----- From: "Crispin Pemberton-Pigott" <[email protected]> To: "Discussion of biomass cooking stoves" <[email protected]> Cc: "Ron Larson" <[email protected]> Sent: Sunday, August 1, 2010 6:31:17 PM Subject: RE: [Stoves] Stove Testing Lab in UB !! Dear Ron I will give it a quick shot: 1. Is the lab pretty much going to be reserved for coal-burning stoves? Anything people burn we will test: coal, wood, wood briquettes, oil, rubber, coked fuels, anthracite, semi-coked coal briquettes, raw coal briquettes with many of them being in the semi-coked categories. 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? Could one family coke for another (the idea that brought me into TLUD design for wood in 1995). 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. ] 2. I gather that particulate emission is particularly bad with coal in UB - or is it just as bad from most wood burning stoves in other parts of the world? The local inversion conditions in winter are particularly disadvantageous. Wood, though forming a small portion of the total energy generated, is a significant polluter on a per kg basis. It is used to ignite coal. [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? I have no experience with BLDD, but would guess the same should prevail - with the added advantage you can keep it going.] 3. Re this sentence: "The total range of the particulate concentration from a bad stove during ignition to a good stove during flaming pyrolysis is 10,000:1." a. Do you feel this is true of wood burning stoves as well? It is true of wood burned under a pile of coal early in the ignition phase. The lower the volatile content of the fuel, the more wood needed to light it (so far, anyway). Wood gives off extremely dense smoke at time and is very clean burning at others. In general it never burns as hot as coal on its own so it might put out PM emissions that are always higher than a hot, clean coal fire. [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. Your use of "migh" and "always" in last sentence need further comment. I have gathered from the comments of John Davies, that coal was always pretty bad until one had turned the coal to coke. 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.] b. <snip> c. Is your statement about 98% relief related to a conversion to BLDD (Bottom Lit Down Draft) I have seen three completely different stove types that are at least 98% lower in CO emissions during ignition. At this time the PM roughly correlate with PM. We are on the verge of being able to say this definitively. The three are the crossdraft stove described here recently, the bottom-lit downdraft and the end-lit cross-draft. [RWL: Below you include TLUDs in a similar list. Have they been tried and do you believe they would have same 98% factor? 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? ] d, e. <snip> f. Does "flaming pyrolysis" imply testing of both DD and UD (with appropriate BL and TL modifiers?) Yes. To date, much against expectation, I can achieve greater emission reductions by changing the lighting and operating procedure than has been achieved by any ‘improved stove’ that made it to market in the past 10 years. Extensive work by the WB and ADB and others shows that actual saving of fuel between a traditional and improved stove (which everyone has related to emissions with little evidence at all) is about 10%. Adopting the Basenjengo Magogo lighting technique adapted to the stove clearly reduces emissions dramatically and increases thermal efficiency. I will put a figure on that within a couple of weeks. [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). 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. 4. <snip> 5. The standard (?) heating stove in many nordic and slavic countries has a single ignition each day with the chimney having a long tortuous path to the roof - in order to capture and store the energy. Would that work in UB? The problem with that is that the efficiency would rise to the point that the exit temperature would be well below the point at which H2S would condense and eat the pipes. At this time getting the heat has not been an issue. The thermal efficiency of a traditional stove is about 65%. This can be raised to 80%. Above that the draft reduces dangerously unless the power level is perhaps in the 12 kW range. [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. 6. Is there a role for more energy efficiency (bigger wall/ceiling R-values) and solar space heating (both active and passive)? Randy at U of Waterloo has modelled the building with a general case spreadsheet and it includes the solar input. Maybe, the answer to your question. We can model the influence. I hope so. Insulating the gers (yurts) is very effective however it also raises the CO because the stoves are leaky. Well sealed, people may be badly affected. We have to change the stoves and reduce their heat output which is quite hard to do below 5 kW. Reducing the size of a semi-coke briquette fire is quite difficult. Only 600 or 700 g per hour would be needed. There is no practical stove in that category. The fuels are speculative at best and the housing improvement people are not really talking to the stove people about what the heat demand is. There are no stoves suited to a really well insulated small house. [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. I built house 5 years ago with 10 inch walls and wish now I had followed EU practice of even thicker, higher R-values. Your clients should be alerted to the fact that they could probably recoup a wall - ceiling revamp in just a few years by saving 3/4 of their present fuel bill (using your numbers) 7. You cite 400,000 ignitions per day. What is the total number of stoves in UB? What is the relationship between space-heating and cooking? Same stove? Started sometimes for cooking only? Heating and cooking is done on the same stove. When it is not all that cold, people light the stove 3 or 4 times a day. In mid-winter it is running most of the time and the air is much cleaner. This winter it was 12 C below normal and the coming one looks like it will be as bad or worse. Because of this, most people kept their stoves going and the air was unusually clear in Jan-Fed. [ RWL: Still wondering about the number of stoves - sounds like it might be about 100k? Just alerting small stove entrepreneurs - willing to work with solar hot water companies (in Sweden you can but wood furnaces that are already designed to be used with your solar collectors. The Chinese (relatively nearby) have installed I think 70% of all the solar hot water systems in the world. 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. They can dispense with most of the large hot water storage tank I have (another way to cut down on number of fire-starts). ] 8. [RWL < snip rest - Thanks again> .
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