# Is Clean Coal on a very small scale possible? **URL:** \ **Category:** Factual Questions\ **Created:** [September 11, 2016, 4:07pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666 "2016-09-11T16:07:16Z")\ **Posts on this page:** 6\ **Page:** 3
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [September 12, 2016, 6:09pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/41 "2016-09-12T18:09:55Z")
> [@am77494](#): > > 2\> Pyrolysis of wood produces a lot of carcinogens - like phenol, formaldehyde, etc. In an Industrial setting, proper air control and temperatures keep these to a minimum - however in small furnace like the OP’s these cannot be effectively controlled especially if the wood is wet or when she/he is starting up or shutting down. Agreed. > [@](#): > > 3\> The ash (or rather the mineral matter) of wood has a very low fusion point compared to the ash in coal. You will have clinkers in the furnace bottoms and ash/resin (from pyrolysis) deposits all over the place. it depends on the coal and depends on the wood. In general, you are correct, but not universally. > [@](#): > > 4\> Disposing the ash from the furnace will be another concern - wood ash is alkaline with a lot of Sodium, Potassium and Calcium It depends on the coal and depends on the wood. PRB coal ash is highly alkaline, for example, although not likely to be burned in a pizza oven, for many reasons. > [@](#): > > 5\> For the same amount of net heat, you will produce more CO2 with wood than with coal. Because 1. Coal burns hotter (higher cal/kg) and 2. Wood has a lot of moisture in it (even when it appears dry) and much of the heat of burning goes towards vaporizing the moisture. True (for most coals and wood…), but the hope is that some portion of the CO2 from the wood is carbon-neutral (that portion may be small to nonexistent, depending on how the wood is grown, harvested, prepared, and transported). ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [September 12, 2016, 7:14pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/42 "2016-09-12T19:14:10Z")
> [@am77494](#): > > I don’t agree with you. Coal used in an IGCC plant is the cleanest fossil fuel - even cleaner than Natural Gas in terms of particulates and SOx. Everything is cleaner than something else in terms of cherry-picked parameters, but the fact remains that anything that relies on coal as its energy source is going to suffer from the previously cited CO2 emission problems, barring the use of large-scale and unproven sequestration technologies. For this reason, political initiatives have arisen to [restrict IGCC plants](https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle#IGCC_emission_controversy) along with all other forms of coal-fired generation. Indeed the Province of Ontario demolished the last of its coal-fired power plants some years ago, for good reason, and now relies primarily on nuclear, hydro, and increasing amounts of solar and wind for power generation. > [@am77494](#): > > For the OP’s application, Coal is the best for the following reasons : > > 1\> The high temperatures and heat fluxes required for cooking is best provided by coal. Ask anyone who has used a gas grill versus charcoal grill. My argument is not a culinary one, although I have to say personally I haven’t found this. If I preheat my gas barbecue on medium-high more than about ten or fifteen minutes, the thermometer goes right off the scale and it gets hot enough to sear the living daylights out of anything I put on it! > [@am77494](#): > > 2\> Pyrolysis of wood produces a lot of carcinogens - like phenol, formaldehyde, etc. In an Industrial setting, proper air control and temperatures keep these to a minimum - however in small furnace like the OP’s these cannot be effectively controlled especially if the wood is wet or when she/he is starting up or shutting down. I believe this is true but (a) coal (depending on type) produces its own noxious emissions, notably SO2, NOx, and others, and (b) wood is not a candidate for a general-purpose mass-market fossil fuel, while coal and coal derivatives have been, in many cases remain so (mainly in power generation), and the industry is pushing for an expanded role. > [@am77494](#): > > 3\> The ash (or rather the mineral matter) of wood has a very low fusion point compared to the ash in coal. You will have clinkers in the furnace bottoms and ash/resin (from pyrolysis) deposits all over the place. I don’t see the relevance of this. > [@am77494](#): > > 4\> Disposing the ash from the furnace will be another concern - wood ash is alkaline with a lot of Sodium, Potassium and Calcium Except that wood ash is a well-recognized commonly used fertilizer, specifically because of the potassium and other useful nutrients, and the alkalinity and other side effects are dealt with through appropriately measured use and/or composting the ash. [Coal ash, not so much](http://www.scientificamerican.com/article/coal-ash-in-soil/), in part because of toxins like arsenic, mercury, lead, and other heavy metals, and also because of elevated radioactivity as previously mentioned. > [@am77494](#): > > 5\> For the same amount of net heat, you will produce more CO2 with wood than with coal. Because 1. Coal burns hotter (higher cal/kg) and 2. Wood has a lot of moisture in it (even when it appears dry) and much of the heat of burning goes towards vaporizing the moisture. Did you understand my point about wood (and biomass in general) essentially recirculating CO2 from the existing carbon cycle, while coal releases net new CO2 from millions of years ago? ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [September 12, 2016, 8:43pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/43 "2016-09-12T20:43:45Z")
> [@Una\_Persson](#): > > What are you basing this on? Most biomass fuels I work with are between 1-5% ash, whereas coal is almost always from 5-20% ash in the US, and in India and places which burn high-ash lignite, as much as 40-50% ash. Some biomass fuels need fluxant to control the Ash Fusion Temperature - maybe that is why he is seeing increased ash. You don’t need to add fluxant if you are blending if the proper ash chemistry can be achieved. India’s lignite has lot of extraneous mineral matter (dirt) mixed into it. We did some project where washing the coal brought the mineral matter to a much lower level. But generally, lower the rank of coal (lignite is low rank) lesser the ash and lesser the ash fusion temperature. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [September 12, 2016, 9:10pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/44 "2016-09-12T21:10:52Z")
> [@wolfpup](#): > > Everything is cleaner than something else in terms of cherry-picked parameters, but the fact remains that anything that relies on coal as its energy source is going to suffer from the previously cited CO2 emission problems, barring the use of large-scale and unproven sequestration technologies. For this reason, political initiatives have arisen to [restrict IGCC plants](https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle#IGCC_emission_controversy) along with all other forms of coal-fired generation. Indeed the Province of Ontario demolished the last of its coal-fired power plants some years ago, for good reason, and That goes both way. Cherry picking parameters to prove a coal fired cooking furnace is worse than a wood fired one is still doing the same thing. And IGCC is not for sequestration - it is just a way of making clean power from coal.[cite](https://www.wired.com/2016/07/charcoal-grilling-tastes-better-gas-just-science/) > [@wolfpup](#): > > …now relies primarily on nuclear, hydro, and increasing amounts of solar and wind for power generation. Again you are cherry picking Nuclear power plants have an efficiency of 30 to 35 % . All the waste heat of the nuclear plant goes to the water bodies near it and has really created environmental problems. Hydro is bad for fish - the US has recently demolished many dams to restore fish populations. Wind has a low capacity factor - you have to build other power production infrastructure to offset. The lowest winds are during mid-day and usually power demands peak mid-day. > [@wolfpup](#): > > .My argument is not a culinary one, although I have to say personally I haven’t found this. If I preheat my gas barbecue on medium-high more than about ten or fifteen minutes, the thermometer goes right off the scale and it gets hot enough to sear the living daylights out of anything I put on it! [Charcoal Grilling Tastes Better Than Gas. It’s Just Science](https://www.wired.com/2016/07/charcoal-grilling-tastes-better-gas-just-science/) > [@wolfpup](#): > > I believe this is true but (a) coal (depending on type) produces its own noxious emissions, notably SO2, NOx, and others, Again, looks like you are not reading what is being said. Read - Una’s note - NOx is not a result of fuel but a result of Flame temperature and Excess Oxygen. In fact, the Ammonia in coal helps in reducing NOx by reacting with it. > [@wolfpup](#): > > I don’t see the relevance of this. The relevance to help the OP make the choice between wood and coal. > [@wolfpup](#): > > Except that wood ash is a well-recognized commonly used fertilizer, specifically … Did you read that my bullet points were for : “For the OP’s application, Coal is the best for the following reasons :” > [@wolfpup](#): > > Did you understand my point about wood (and biomass in general) essentially recirculating CO2 from the existing carbon cycle, while coal releases net new CO2 from millions of years ago? Do you understand the context of my post ? BTW - by the time you figure in the fossil fuels used in cutting down, sizing, drying and transporting the wood from the forest to the OP, all those CO2 carbon cycle benefits are lost. In fact, I wont be surprised if the net CO2 emissions are higher ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [September 12, 2016, 9:12pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/45 "2016-09-12T21:12:33Z")
> [@Una\_Persson](#): > > True (for most coals and wood…), but the hope is that some portion of the CO2 from the wood is carbon-neutral (that portion may be small to nonexistent, depending on how the wood is grown, harvested, prepared, and transported). Exactly this. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [September 12, 2016, 10:32pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/46 "2016-09-12T22:32:27Z")
> [@am77494](#): > > Exactly this. That’s fine, but it seems to be skirting the actual question. There is some emissions burden associated with the production of all fuels, but the apples-to-apples comparison is the _ **intrinsic** _ emissions accruing to the fuel itself. In this respect the CO2 from burning wood and the CO2 from coal are fundamentally different, wood essentially recirculating the CO2 in the contemporary carbon cycle, while coal produces net new CO2 emissions. That is a huge, huge difference, and the core problem with ALL fossil fuels. [Previous page](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666.md?page=2)