# 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:** 20\ **Page:** 2
**Author:** ![Clark\_Cello](https://avatars.discourse-cdn.com/v4/letter/c/58f4c7/32.png) [@Clark\_Cello](https://boards.straightdope.com/u/Clark_Cello)\ **Post date:** [September 12, 2016, 11:45am UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/21 "2016-09-12T11:45:39Z")
> [@bob\_2](#): > > Maybe I am a philistine, but for me it’s just a gimmick. On a barbeque the smoke alters the taste of whatever is being cooked. In an oven, there is only heat - how that heat is achieved is surely incidental to the taste and quality of the final product. If one pizza chain makes better pizza, it is surely more to do with preparation and recipe than the source of the heat. I think the magnitude of heat is the point, which is related to the source. For some types of pizza, you want to oven very, very hot, which is easier to do with coal. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [September 12, 2016, 11:48am UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/22 "2016-09-12T11:48:35Z")
> [@kanicbird](#): > > IDK if they could be done to the standards that powerplants can, but certainly some aspects could be implemented such as particle capture, perhaps a liquid spray like used in diesel vehicles. However I don’t know if scaling down powerplant tech is the best solution instead of redesigning it for the application mentioned here. On diesel-engine vehicles, the liquid spray you are referring to is [diesel exhaust fluid, or DEF.](https://en.wikipedia.org/wiki/Diesel_exhaust_fluid) It contains urea, which breaks down into ammonia in the hot exhaust. This sounds bad, but in conjunction with a special catalytic converter in the exhaust system, it breaks down the nitrogen oxides. Injected in the proper amounts, you don’t end up with ammonia coming out of the tailpipe, and you get rid of most of the NO[sub]x[/sub]. soot is captured (and intermittently burned off) by a [diesel particulate filter (DPF),](https://en.wikipedia.org/wiki/Diesel_particulate_filter) which is positioned upstream of the SCR described in the previous paragraph. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [September 12, 2016, 1:11pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/23 "2016-09-12T13:11:33Z")
I’m with the Philistine here … coal is a major hassle to haul in, store, shovel into the firebox, haul away ashes … with natural gas we just use the atmosphere for our sewer, easy as pizza pie. ---
**Author:** ![Duke\_of\_Rat](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@Duke\_of\_Rat](https://boards.straightdope.com/u/Duke_of_Rat)\ **Post date:** [September 12, 2016, 1:24pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/24 "2016-09-12T13:24:04Z")
> [@TriPolar](#): > > Sooner or later we’re going to have to choose our poison, there won’t be any truly clean efficient source of energy until 10-20 years from now when the fusion plants go online. And that ‘now’ will be valid for at least 10-20 more years from now. Are there even any fusion pilot reactors in operation? Has anybody even produced a sustainable fusion reaction (power plant type, not a bomb)? I imagine it’d take 10 years to get the permits and construct the plant if we had a viable pilot reactor that could be scaled up right now. To think that there will be commercial power plant sized fusion reactors in 10 years is a bit of a stretch, and I wouldn’t put money on 20 years. As for the pizza oven - coal has got such a bad rap from power plant use that now we are worried about emissions from a pizza oven? ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [September 12, 2016, 1:38pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/25 "2016-09-12T13:38:52Z")
> [@Duke\_of\_Rat](#): > > Are there even any fusion pilot reactors in operation? Has anybody even produced a sustainable fusion reaction (power plant type, not a bomb)? > > I imagine it’d take 10 years to get the permits and construct the plant if we had a viable pilot reactor that could be scaled up right now. To think that there will be commercial power plant sized fusion reactors in 10 years is a bit of a stretch, and I wouldn’t put money on 20 years. > > As for the pizza oven - coal has got such a bad rap from power plant use that now we are worried about emissions from a pizza oven? As far as I know, there’s no fusion reactors of any kind. We’re still a very long ways off on that technology to be used as a general energy source. Fission reactors are going to take longer than 10 - 20 years to get online, 40 - 50 years more likely the way we build them today. If we could settle on one single design and get that all the various approvals for it, then we could start building them _en masse_ without all the delays. It would still be decades before enough were built to replace fossil fuels, and more likely as the nuclear plants come on-line we’ll just start using more electricity … I can’t speak to coal burning because we have very little of that around here. Wood burning on the other paw is heavily and very strictly regulated. When there’s an inversion in the atmosphere burning wood is prohibited (unless it’s one’s sole source of heat). This can go on for weeks at a time and I just can’t imagine a pizza place shutting down for that long and still stay in business. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [September 12, 2016, 1:42pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/26 "2016-09-12T13:42:27Z")
> [@Duke\_of\_Rat](#): > > As for the pizza oven - coal has got such a bad rap from power plant use that now we are worried about emissions from a pizza oven? In certain areas that are struggling to meet [NAAQS,](https://en.wikipedia.org/wiki/National_Ambient_Air_Quality_Standards) anything burning wood or coal without scrubbing the exhaust is going to be a problem. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [September 12, 2016, 3:31pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/27 "2016-09-12T15:31:32Z")
> [@Duke\_of\_Rat](#): > > Are there even any fusion pilot reactors in operation? Has anybody even produced a sustainable fusion reaction (power plant type, not a bomb)? > > I imagine it’d take 10 years to get the permits and construct the plant if we had a viable pilot reactor that could be scaled up right now. To think that there will be commercial power plant sized fusion reactors in 10 years is a bit of a stretch, and I wouldn’t put money on 20 years. > > As for the pizza oven - coal has got such a bad rap from power plant use that now we are worried about emissions from a pizza oven? It’s only 10-20 years away. It will stay 10-20 years away for a long time. ---
**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, 3:38pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/28 "2016-09-12T15:38:59Z")
> [@AskNott](#): > > Can a coal-fired pizza joint keep from polluting the air, at least partly? Yes absolutely. If your primary focus is on removing pollutants like SOx and NOx. Small scale sewage treatment plants do it all the time with H2S that is generated during anaerobic treatment. Its a simple scrubber with water or alkali (as mentioned before) - you may run into problems disposing the waste water though. > [@AskNott](#): > > Today, coal-fired power plants employ some methods to reduce sulfur dioxide, soot and such. I don’t understand any of those methods, I’ll tell you up front. Can any of them be used on a scaled-down pizza oven size? There’s no soot in coal fired plants (unless the air control goes bad) - there is fly ash though. But fly ash is more a result of the powerplants pulverizing (powdering) the coal. For sulfur dioxide control, some power plants use lower rank coal (like sub-bituminous or powder river basin) and/or scrubbers. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [September 12, 2016, 3:48pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/29 "2016-09-12T15:48:05Z")
Why would you even worry about a pizza oven? How many pounds of coal does one burn per day? Your average 500 megawatt coal-fired powerplant burns something on the order of 3835 tons per DAY, or 159 per HOUR. A pizza place that burned a ton per day (way, way high, in my non-expert opinion) isn’t even a rounding error on the pollution scales when compared to coal power generation. ---
**Author:** ![Duke\_of\_Rat](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@Duke\_of\_Rat](https://boards.straightdope.com/u/Duke_of_Rat)\ **Post date:** [September 12, 2016, 3:50pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/30 "2016-09-12T15:50:04Z")
> [@TriPolar](#): > > It’s only 10-20 years away. It will stay 10-20 years away for a long time. Yeah, like the sign hanging in the bar: “Free Beer Tomorrow” ---
**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, 3:52pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/31 "2016-09-12T15:52:38Z")
> [@wolfpup](#): > > In fact, coal is the worst and dirtiest of all the common fossil fuels for a number of reasons 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. 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. 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. 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. 4\> Disposing the ash from the furnace will be another concern - wood ash is alkaline with a lot of Sodium, Potassium and Calcium 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. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [September 12, 2016, 4:02pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/32 "2016-09-12T16:02:49Z")
I’ve used electric muffle furnaces up to 1200 deg C, and while it was against several regulations, I can attest they would make an excellent pizza at around 575 deg C. I don’t think coal can do anything that electricity can’t. ---
**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, 4:18pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/33 "2016-09-12T16:18:34Z")
> [@Bill\_Door](#): > > I don’t think coal can do anything that electricity can’t. Try converting Iron Ore to Steel with electricity 🙂 ---
**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, 4:37pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/34 "2016-09-12T16:37:30Z")
> [@Bill\_Door](#): > > I’ve used electric muffle furnaces up to 1200 deg C, and while it was against several regulations, I can attest they would make an excellent pizza at around 575 deg C. I don’t think coal can do anything that electricity can’t. Coal burns on the average at around 2000 deg C (3500 F) - and with a coal furnace you have the ability to quickly raise the heat flux or reduce it. You can get the item to be heated quickly to high temperature too (the pizza) in this case. And you can do it in a small volume. I work on forges as a hobby, and when precise control of temperature is required I opt for an electric forge. When smaller pieces are involves, I opt for a propane forge. But when really large pieces are involved, coal forges work the best. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [September 12, 2016, 4:41pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/35 "2016-09-12T16:41:45Z")
> [@am77494](#): > > Try converting Iron Ore to Steel with electricity 🙂 Which is how it’s done (maybe not in China). > [@](#): > > Iron is manufactured in a blast furnace. First, iron ore is mixed with coke and heated to form an iron-rich clinker called ‘sinter’. Sintering is an important part of the overall process as it reduces waste and provides an efficient raw material for iron making.~~ > > Basic oxygen steelmaking > > Hot metal from the blast furnace and steel scrap are the principal materials used in Basic Oxygen Steelmaking (BOS). Modern furnaces, or ‘converters’ will take a charge of up to 350 tonnes and convert it into steel in around 15 minutes. A water-cooled oxygen lance is lowered into the converter and high-purity oxygen is blown on to the metal at very high pressure. The oxygen combines with carbon and other unwanted elements, eliminating them from the molten charge. These oxidation reactions produce heat, and the temperature of the metal is controlled by the quantity of added scrap. > > [Steel manufacture - SteelConstruction.info](http://www.steelconstruction.info/Steel_manufacture) ---
**Author:** ![puddleglum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puddleglum/32/137_2.png) [@puddleglum](https://boards.straightdope.com/u/puddleglum)\ **Post date:** [September 12, 2016, 5:07pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/36 "2016-09-12T17:07:01Z")
> [@bob\_2](#): > > Maybe I am a philistine, but for me it’s just a gimmick. On a barbeque the smoke alters the taste of whatever is being cooked. In an oven, there is only heat - how that heat is achieved is surely incidental to the taste and quality of the final product. If one pizza chain makes better pizza, it is surely more to do with preparation and recipe than the source of the heat. Coal burns hotter than wood and hotter than gas. It might be possible to get an electric oven up to temperatures of around 900 degrees but it is not commonly done. Temperatures at this level produce a crust that is crisp on the bottom and cooked through. Nothing produces a better pizza crust than coal fired ovens. ---
**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, 5:36pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/37 "2016-09-12T17:36:23Z")
> [@bob\_2](#): > > Which is how it’s done (maybe not in China). Sorry, I did not understand your post. From you own cite - " First, iron ore is mixed with coke and heated to form an iron-rich clinker called ‘sinter"". IIRC - Coke is made from **coal**. ---
**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, 5:56pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/38 "2016-09-12T17:56:17Z")
> [@engineer\_comp\_geek](#): > > Generally speaking, biomass plants produce about the same amount of ash and particulates as coal plants. However, coal plants produce a lot more sulfur dioxide and sulfur compounds. 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. ---
**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, 6:04pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/39 "2016-09-12T18:04:55Z")
Some points being missed in the pizza oven question: 1. The pizza oven almost assuredly is producing more emissions per pound of coal burned than a modern coal-fired power plant. The exception being NOx emissions, as those are mostly a function of the combustion temperature, and the here the combustion temperature of the pizza oven is likely half the peak combustion temperature of a pulverized coal furnace. 2. Most pizza ovens use a low-sulfur anthracite coal, which means that their SO2 emissions are not super-high, but since they have no scrubber they certainly are much higher than seen at a coal plant with any sort of SO2 control on, even dry sorbent injection. 3. Particulate emissions are likely pretty high as well, much higher than a coal plant. I sincerely doubt a pizza oven has a baghouse on it, let alone an ESP. Probably not even a cyclone separator. 4. All the mercury, arsenic, cadmium, and other heavy metals in the coal are going right up the stack. 5. The relatively low combustion temperatures of the coal can result in some dioxin and furan emissions, especially from the “colder” areas of the fire. 6. You have no idea how complicated some of the “simple” solutions turn out to be. I’ve worked at close to 650 coal-fired power plants in 16 countries(and maybe 50 biomass plants, I don’t know how many gas and oil and other fuel plants). I’m working for several of them right this minute. Without some extraordinary effort you are not likely to have a viable solution to make a pizza oven be as “clean” as a modern coal power plant with modern emissions controls on it. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [September 12, 2016, 6:04pm UTC](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666/40 "2016-09-12T18:04:57Z")
> [@bob\_2](#): > > Which is how it’s done (maybe not in China). Pig iron is converted into steel in a basic oxygen furnace, but AFAIK, the blast furnaces that convert iron ore into pig iron are still mostly coke-fired (coke being a coal-derived fuel), since the CO produced helps reduce iron oxide in the furnace. [Previous page](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666.md?page=1) [Next page](https://boards.straightdope.com/t/is-clean-coal-on-a-very-small-scale-possible/765666.md?page=3)