From the IEA Clean Coal Centre
– when the data fit the model, and mercury emissions come for free
Mercury is a menace. It is an environmental liability and global emissions of this toxic metal continue to increase.
(Several reports on mercury have been produced by the IEA Clean Coal Centre and all are available as free, one-click downloads from our library.)
Mercury behaviour in coal-fired power plants is complex. It can be modelled and predicted, to some extent, but low concentrations and complex measurement challenges mean that data gathered in the field are often … well, different to what one might expect. Mass balances, the complete tracking of mercury from coal through to emissions and waste materials, rarely actually balance in practice. Measured concentrations will imply that either mercury has vanished into thin air, or even more weirdly, has appeared out of nowhere. This is generally accepted as something we just have to deal with – statistical variance and uncertainty.
And so there are often generalisations made about mercury behaviour to help those working with coal plants to make expert judgments on the best methods to reduce emissions. These are included within the BAT/BEP (best available technology, best environmental practice) guidance documents which support the Minamata Convention, the global legally binding instrument ratified in 2017 designed to control and reduce mercury emissions to the atmosphere from all sources. For example, it is accepted that plants firing low grade coals are likely to release more mercury than plants firing higher grade coals. Similarly, plants installed with control systems for sulphate and nitrate control (flue gas desulphurisation systems and selective catalytic reduction), are likely to report emissions up to 80 or even 90% lower than plants without these devices. Plants with electrostatic precipitators (ESPs) only particulate control systems such as baghouses/fabric filters, would be expected to control mercury emissions by around 30-70% (usually at the lower end of this range) depending on plant and coal parameters. Plants with ESPs would be expected to achieve significantly lower mercury emissions, commonly well under 40%, and would only achieve up to 60% control under very rare conditions.
And so when our hosts in Bogota reported that their ESPs were controlling 90% of the mercury emissions from TermoPaipa unit 4, we smiled politely and assumed that their data were wrong. 90% mercury control with an ESP alone? That was clearly either bad data or black magic!
But we visited the plant, looked at the coal data (produced in a separate project with Alan Kolker of the US Geological Survey) along with the data for the waste streams and the stack. The coal mercury content was low, but not uniquely so. But the stack emissions were at or below 1 microgram/m3 – a value which would be in compliance with the most challenging of global emission limits. Most plants in the USA and the EU can only dream of reaching a mercury emission value of 1 microgram/m3 without spending significant money on mercury control measures. And we couldn’t for the life of us understand why this plant was achieving such low emissions “for free”. So we sat down and literally plugged the numbers available to us – coal, boiler and other plant operating conditions, all the data we could get our hands on – into the iPOG, the mercury emission calculation tool produced by Niksa and Associates in the USA on behalf of IEA CCC and the UN Coal Partnership. The iPOG tool is an excel programme based on data from over 1,000 data sets from actual plant measurements in the USA, India, Russia, South Africa and China. It is available as a free download from the UN Coal Partnership website.
And lo and behold – the data matched the model! A Christmas modelling miracle. A plant fitted only with an ESP was indeed achieving fantastically low mercury emissions to air. And the reason why this coal/plant configuration achieved such a feat? – A combination of a very clean coal and a boiler running just a little less efficiently than it should. Mercury in Colombian coal is low. Chlorine is moderate – helping to oxidise the mercury to make it “sticky” enough to attach to any fly ash materials which have some form of sorbent characteristics … unburned carbon being the ideal surface. And so, a boiler running at a slightly lower efficiency than perhaps it should, producing 10-12% LOI (loss on ignition/unburned carbon) provides inherent sorbent, perfectly placed to capture the now oxidised mercury within the fly ash. Voila! 90% of the mercury is captured. Consistently.
This is excellent news for Colombia, a country which produces and sells a lot of high quality coal worldwide. And, although Colombia is largely powered by hydro plants, it is possible that coal use could increase in future to provide baseload to a growing population where hydro potential has peaked.
HT/Crispin in Waterloo
“ unburned carbon being the ideal surface.”
Merry Christmas. Carbon pollution is a good thing.
Dr. Willie Soon has talked about this non problem in one of his videos.
https://ca.video.search.yahoo.com/yhs/search?fr=yhs-rogers-rogers_001&hsimp=yhs-rogers_001&hspart=rogers&p=wille+soon+mercury+youtiube#id=51&vid=e76698861e627da34d8b23a85734a3b1&action=click
Mercury may be low in Columbian coal… but there’s blood on that coal…
From your favourite news source (but widely reported elsewhere)
https://www.theguardian.com/environment/climate-consensus-97-per-cent/2018/oct/25/blood-coal-irelands-dirty-secret
How do you feel about Polish coal companies sponsoring the latest COP conference? Did the climate saving delegates turn in disgust and anger at the door, when they saw that the lobby was filled will samples of coal and products based on coal? Or did they sit on their conscience and accept the money for food and hotel from the UN disbursement office? There were 406 delegates from the small African country of Guinea. How much co2 did they emit flying back and forth?
Griff: And folk are dying of cold every winter because of your excessive power costs, murderer.
Griff
Your problem is that you think we don’t know that the murderous FARC leftovers still haunt La Guajira.
Then there is the official ‘La Guajira’ “encampments” where the former murderous Communists are located.
This besides the Government funded “Relocation” and “Processing” camps for Former FARC murderous Communists, who seem to be having a problem reinstating back into a civil society.
The FARC still don’t want the filthy money making capitalists in Columbia.
They are the root cause of getting in everybody’s way, so as to “Bugger” things up and return life to the good old days.
Unfortunately for you, the overwhelming vote of the average Colombian voted for freedom and capitalism.
As noted in the highly partisan article you provided, the land was assumed under legal expropriation orders and the inhabitants provided relocation resources, alternatives sites and funds.
However, somebody interfered, with the clear intent to create a humanitarian mess and paint the EVIL Coal Company and the now Freedom loving capitalist oriented Colombian Government and it’s security forces as Filthy Cruel Capitalists, intent on crushing the little people.
Nothing is further from the truth.
The “Victimized” locals deliberately chose to flout the resettlement offer, with assistance from “Activists” and then a hard core of these “Victimized” locals and Activists chose to interfere, often violently, with Mine Operations, Miners and Government workers.
This is the reason why there are so many problems with the mine operation.
This is also the reason why anybody caught on any mite property or who refuses to “move on” or is caught destroying or interfering with Mine Operations is dealt with severely.
As they should be.
The following violent confrontations between the “Cannon Fodder” used by the Activists, which is often the useful idiots that were conned into staying, the core of the Activists “Victimized” locals and anybody they deem a target, legitimate or otherwise, is and was entirely predictable.
So, nice try, no cigar.
Great response, iain na hearadh December 17, 2018 at 1:56 am.
And thank you for real information. Unlike the fake stuff giffiepoo is always dropping.
Not only “no cigar”, giffiepoo doesn’t even get an old mentholated cigarrette butt with lipstick.
I thought griff told Anthony that he was too good for us, and wouldn’t be back?
He did, but where else do you go to get real climate news?
An article from the Guardian so we know it’s junk before even reading 🙂
griff really does cling to his favorite myths.
i don’t know Griff that well. Is he really a Communist?
Wind him up, you’ll find out!
Griff,
When the thugs in Columbia get as horrible and ruthless and gutless as Al Gore, then we’ve got BIG problems.
I’m somewhat surprised that this wasn’t already known. I would have thought that someone would have taken samples from a plant over a range of operating conditions.
Perhaps somebody wanted to do this useful research but couldn’t get funding for it because too much money was being pi$$ed away on so many other useless projects about global warming.
Maybe the Colombians don’t have hydrargyrumphobia.
Everyone has to do the tests, but the numbers rarely get farther than the EPA regional office. I would never publish my stack test results if I could help it, especially if they might not be believed or are too good to be true. The philosophy in environmental is to keep your head down so it doesn’t get cut off.
Yes, that sounds like good lawyerly advice.
I guess there is no advantage in bettering the regulatory requirements anyway, because the EPA will simply set the bar higher. They long since stopped trying to actually protect the environment in a sensible cost-effective manner. Since the Obama regime it is clear the EPA regards it as its job to eliminate the coal industry, not to regulate it for everyone’s benefit.
Ben,
Emissions are a matter of public record in the US. Stack tests are public records, even if not required by permit. They are reported to the governing air pollution control folks. What happens after that is out of the hands of the facility.
How far those stack test reports go after the regulators get them is up to the regulators. They usually don’t go much farther than being on file and the reading file for the next permit revision unless an activist group does a FOIA.
So true Ben of Houston
My experience with the TNRCC (TCEQ) was never positive. We were politely Grandfathered in, until we tried some new stuff at the plant. Yes, we were able to demonstate “O” emissions, for our permit. We then got the good news. O was the new permitted limit.
And I thought 1 was the loneliest number that I ever knew.
Good one, Mr. Hart. At least in the US, the absorption of mercury onto unburned carbon, also called “native capture,” is well known and depended on for compliance with the mercury limits on many coal plants. Some very efficient boilers with low unburned carbon have been “detuned” to produce more LOI for just this reason. Others have installed powdered activated carbon systems to capture mercury, but this means at least some of them have also installed baghouses to clean out the additional particulates. A few hundred million here and a few there, soon you are talking real money.
oeman50
This is a topic on which one should be pedantic. The mercury is not absorbed into the material, it is adsorbed onto the surface of the carbon. There in fact many C-Hg combinations possible so one can speculate that additional reactions are taking place, but the main one is surface adsorption.
I am concerned as to the conditions under which it is released. For example if this were added such a system to a domestic stove and the usual operating temperature in the chimney is 160 C, for example, and it works, under what conditions would mercury be released? Maybe it lets go at 220 C.
It would be very interesting if it turns out that high Hg coal can be burned safely using nothing more than some of the poorly combusted carbon as the adsorbent. That raises possibilities for adsorbing or absorbing arsenic and fluorine as well.
While these principles and effects have been know for a while, it is an accident that the Columbian station was running so clean. It is a little ironic to find that as environmental regulations have mandated ever-better combustion efficiency and a reduction of black carbon in the exhaust, it has the unintended effect of releasing a higher fraction of the elemental mercury.
Crispin
There are ALWAYS unintended consequences, which should always be looked for. It is a direct corollary of Murphy’s Law.
So, the reasonable assumption here, is that dirty coal, that is processed for actual harmful outputs, using Co2 as a filter, is the way to go.
This then makes for an actual “Clean Coal” operation, as opposed to the assorted Carpetbaggers, so called environmentalists, and the Green Gaia worshiping Mafia where “clean coal” is an insulting oxymoron.
Not to mention the Sierra Club and the assorted lunatics that commit law-fare on any project that won’t return humanity back to the Stone-age.
So, if this method produces such good results, albeit with a an alleged fairly sloppy filtering technology, this then suggests that with a minimal of engineering, this method could be used to produce and promote a much cleaning burning Coal solution.
Where by ‘Clean Coal’, I’m not talking about fealty or deference to Gaian fantasists, or the nonsense from the Green Left Mafia, but actual Coal processing that almost entirely removes heavy metals, actual waste and sedimentary materials.
That has to be good, both for developing countries and the stock pile of “lignite” or “brown coal” that is actually problematic to otherwise use.
As for the Dirdy Carbons, I’m all for setting them free. It’s good for the Planet, after all.
So, plants elsewhere should be lowering boiler efficiency to capture more mercury. OK then, lower efficiency wins again!
SNIP – You’re walking the edge of another ban – MOD Want less violence in Columbia? Kill FARC, all of them.
2Hotel9
This is a topic on which one should be pedantic. They are not saying to lower the efficiency of the boiler. That is a mechanical engineering heat transfer issue. They are saying they lowered the combustion efficiency to produce some PM, probably PM2.5, and created black soot (PM containing black carbon). This soot is then captured on the electrostatic precipitator as a “fur” which has a very high exposed surface area per kg. As I repeat above, the mercury is not absorbed into the material, it is adsorbed onto the surface of the carbon.
When considering the loss of efficiency, one has to consider the options. When adding bag houses and paraphernalia there is an energetic and monetary cost. That lowers the system efficiency. So the question is how to accomplish the goals (clean combustion or cleaned combustion) with a reliable and least expensive solution.
Demanding that people capture CO2, for example, greatly reduces the system efficiency. Releasing CO2 back in to the atmosphere from whence came has numerous benefits.
Guess I got to get a permanent sarc tag.
Green-loony: Oh no no no. This just won’t do. Mercury isn’t the issue, we eco-loons want what King Obama decreed — putting these evil coal companies out of business!
Here in the western US our biggest source of mercury is the pacific ocean.
I am a mechanical engineer in the power industry so my chemical talk may not be totally accurate. Mercury has been an elusive thing to capture and remove. First of all it is almost impossible to measure in the small quantities that it is emitted. The monitoring equipment has gotten better but is still elusive. It is measured in parts per trillion. The concentration also swings widely as coal is burned. The mercury content in the coal is not very consistent. It was originally thought that carbon injection was the solution. However there is particulate, oxidized and unoxidized forms of mercury in the flue gas coming from coal fired power plants. The carbon only captured the oxidized mercury. Catalysts that are installed on power plants to oxidize nitrous oxide to reduce NOx emissions also oxidized mercury. That was good. But, the catalysts also oxidized SO2 to SO3. The SO3 had an attraction for the carbon being injected to capture the mercury. So the SO3 was taking the carbon away from mercury removal. Carbon is an expensive reagent. Well the solution to that was to inject lime upstream of the carbon injection to capture the SO3 so the more expensive carbon would capture the mercury.
Wet scrubbers installed on many coal fired power plants captured some of the mercury as a side benefit of removing SO2. However re-emission of the mercury after removal became an issue. So additives were developed to add to the scrubber liquor to reduce the re-emissions. Remember you are dealing with parts per trillion in concentration. Fine tuning at these low concentrations is almost impossible.
Now add to the fact that the mercury being removed is now contained in fly ash and gypsum generated at the plants. The fly ash is often used in concrete for roads and buildings and the gypsum is often used to make wallboard to be installed in homes etc. So the mercury, as a pollutant, is being removed from the flue gas and ends up in materials that we come into contact with every day.
Oh the web we weave.
Thanks for the info, Gary. I’m also a (retired) mechanical engineer. Seems the mercury and other so-called issues are more & more like repeatedly splitting hairs down to atoms.
Thanks, Gary. Your summary of the issues is pretty good.
I also worked in the electric power industry for a number of years as environmental scientist, and spent a considerable amount of time with the Mercury and Air Toxics (MATS) rule (from commenting on the draft through ongoing compliance with the final rule). The MATS rule certainly was a chore to get through!
Mercury monitoring technology has certainly come a long way from the early days (2005-2008). I was actively involved in getting one of the first continuous Hg monitors certified in accordance with EPA performance specifications in the early part of the 2010s. Also was involved in certifying several Hg sorbent trap monitoring systems. Both can have advantages and disadvantages, depending on how the boiler is operated and what controls are on the back-end.
More to the point of the article, carbon does make a great Hg control. Every coal-fired unit in the US is using some form of carbon to control Hg emissions. I have seen several industrial boilers with high LOI comply with Hg regs with no controls other than an ESP or baghouse. Most utility boilers are using powdered activated carbon (PAC) in the exhaust stream to control Hg. The PAC forms a “filter cake” in baghouses and provides excellent Hg removal. Adding CaBr to the exhaust also helps oxidize Hg and improves the performance of the PAC for Hg control.
The best Hg control I have seen was a control system called ReACT. This system uses an regenerated activated carbon bed that the exhaust gasses flow through. It reduces both SO2 and Hg to almost zero. The activated carbon pellets are then regenerated in a process heater, which drives off the SO2. The off-gas is then used as feed stock to make sulfuric acid. Pretty neat setup, but expensive and probably not cost-effective on small power plants. Here is a link for more info on ReACT for those who are interested:
https://accel.wisconsinpublicservice.com/environment/react.aspx
Hg emissions on the back end of this plant were barely measureable. Several of the sorbent traps that were used to collect Hg samples were below the detection level of the analytical equipment used to measure the concentration. The rest were just over the detection level. The business of measuring nothing is a tricky one!
In response to the article, LOI is the enemy of efficiency. A 10-12% LOI means that you are wasting fuel. A well-tuned modern boiler firing western subbituminous coal should have an LOI of around 1% or less. Units firing eastern bituminous coal may see higher LOI around 5-10%. Regardless, whenever you see your fuel in the exhaust, you are losing money! Reducing LOI to an acceptable amount is one of the keys to operating your plant efficiently. Let’s take a typical 600MW coal-fired plant firing subbituminous coal as an example (I’m using rounded numbers to make the math easier to follow). Let’s start with the following assumptions:
Fuel heat input = 5,000 MMBtu/hr
Fuel Btu content = 10,000 btu/lb
Fuel cost = $25/ton
Capacity factor = 80%
So that would give us:
Fuel input at full load = 5,000 MMBtu/hr / 10,000 Btu/lb *1,000,000Btu/MMBtu * 1 ton/2,000 lb = 250 tons/hr
Fuel cost per hour = $25/ton * 250 tons/hr = $6,250/hr
Total fuel cost/year = $6,250/hr * 8760 hr/year * 80% = $43,800,000/year
Assuming a that LOI can be reduced from 10% to 5%, the fuel cost savings per year would be approximately $2,190,000/year.
Considering that a PAC system with CaBr injection costs between $5-10M, it would take only a few years for it to recover the costs associated with wasting the fuel to control Hg.
Granted, there are a lot of additional “plusses and minuses” that can go into this analysis (such as cost of disposing high-carbon content ash vs using low carbon content ash for beneficial reuse projects, the cost of PAC, value of missing the sale of electricity from the 5% of the fuel that ended up in the ash pile, etc). But the point of this is that there are ways around the problem that don’t involve inefficiency and lost revenue.
My experience and background is very similar to ChrisW. I worked with a couple of coal plants in NY that installed baghouses with activated carbon injection and attained 80% reduction on a routine basis. When the plants had the filter cake tuned in the resulting emissions were at the minimum detectable levels.
ChrisW, I guess we are partners in crime. :). Great addition to my comment. Mercury control is indeed an issue with a lot of variables. One big issue that I thought of after typing my comment was the way coal fired power plants are currently being operated. They were designed as base loaded units with minimal load swings. Some load reduction at night but typically very stable operation. They are now operated as load following plants. This means the fuel flow is up and down, the boiler is operating inefficiently because of the massive swings in the load. This results in unstable operation of the air quality control equipment and wasting of reagents as well as increase in unburned carbon in the fly ash.
Just wait until the idiots learn that there are Uranium and Gold in sea water.
Almost below detection levels, but that should not spoil a good emotional (catastrophic) story.
I love pointing out that lead naturally occurs in ground water outside of pollution. And pointing them to EPA to prove it is just priceless!
On the subject of unburned carbon. There are many many variables that contribute to the unburned carbon content of fly ash. I have worked on very efficient burning coal fired boilers that contain 2 to 3% unburned carbon in the fly ash. I have also worked on units that had up to 20% unburned carbon. The design, operation, and age to the unit all impact the unburned carbon content.
Fly ash used in the cement industry can only contain up to 6% unburned carbon. That may vary slightly depending on several factors.
That carbon is just as capable of removing mercury if it is not bound up with other constituents of the fly ash. And if you go too high the ash cannot be used in industry.
Several utilities have built reburn facilities. The high unburned carbon ash still has some BTU content and the reburning utilizes the remaining BTUs to generate steam or power. It also lowers the unburned carbon content of the ash so that it can be used in the industry.
I received a couple of messages relevant to this topic this morning after alerting him to the article. He notes:
“The thing about elemental carbon is that it is in the form of chain aggregates. The balls stuck together provide both a lot of surface area as well as the opportunity for a negative Kelvin effect that fosters adsorption on the surface at the intersection of the balls.”
That is really interesting. The adsorption is not “on the carbon” so much as near the intersection of BC particles due to the “corners” being more like a flat surface than the outside of a ball. See
http://www.zfm.ethz.ch/d/v/mpc/_private/alt/HS_08/Pratsinis_Ernst/Particle_Formation_Handout.pdf
for ideas.
In terms of US-based ideas, two relevant references are:
Control of Mercury Emissions from Coal-Fired Electric Utility Boilers
from the EPA office of R&D
and
The Role of Activated Carbon in a Comprehensive MATS Strategy, 2014 by Brandon Looney et al
It certainly is, and it may be excellent news for the planet as well.
Mercury pollution can be a serious healh risk, and coal fired power plants are the dominant source for primary mercury pollution. It is great news for all if they have stumbeled upon a cheap and effective method to reduce mercury pollution from power plants.
/Jan
“coal fired power plants are the dominant source for primary mercury pollution. ” no they are not the present less than 2% mercury coming down on the land are from coal fired power plants, the concentration we are taking about are moot to human health, They are only and issue to human health if you are a big enough fool to believe in linear extrapolation of pollutants. There is a point where mercury is a problem and only if you are in an area where is was dumped directly in large amounts or it in the air from have large amount of liquid mercy around(the mercury fountain I the Spanish kings residence certainly was not a good idea) if they is area where mercury was produced or used, it is a problem, the 98% of ocean mercury plus the possible 2% were are adding is not a health problem, if it was we would have been extinct a long time ago, long before coal fire power plants.
I played with mercury when I was a kid. And I turned out all right. All right. All right.
Just a reminder that all this discussion comes from the premise that it will be beneficial to reduce mercury in power plant emissions. We all know about the awful effects from single point source mercury pollution events such as Minimata where doses were high. The relevant question is what are the impacts of diffused mercury emissions that potentially raise background levels. The mechanism of concern for diffuse sources is the concentration of mercury in fish at the predator end of the food chain that are subsequently eaten by humans. The EPA measures the levels of methy-mercury in fish and where concentrations are high enough they recommend for sensitive populations (pregnant women, may become pregnant women, nursing mothers and small children) either not eating (shark, swordfish, king mackerel, tilefish) or limiting your consumption to two 6 ounce servings (shrimp, canned light tuna, salmon, pollock and catfish) per week or one six ounce serving per week from local waters. Serving sizes for children would be smaller. How did these recommendations come about. Specific cases of mercury health impacts on individuals in the US are rare, contested, and in the few possible cases likely the result of unusual and not recommended behavior. Nothing from which a study could be done. The EPA did two long-term studies: one in the Faroe Islands and the other in the Seychelles Islands. Fish consumption is high in both locations They then measured IQ and other measures of well-being at different ages for the children. Statistically they evaluated the impacts for boys and girls. In the Seychelles Islands they found either no effects or positive effects of fish consumption. In the Faroe Islands they found slightly negative effects. However, the diets in the Faroe Islands included mammal fats that also contained other pollutants known to produce the same negative results as mercury. They attempted to remove these effects by analysis, but we can not be sure their impacts are totally removed. For creating the regulations, the EPA chose to use the Faroe Islands study and not the Seychelles Island study. Then they established the concentration level at which the 10% of the most sensitive of the population would be affected. This is standard procedure. Usually, the protective level is set at 1/3 of that concentration. In the case of mercury, the EPA set a safety factor of ten instead of three. Thus we have very conservative standards for health protection for mercury. When it came to evaluating the impact of mercury in the US on the population, the EPA determined there was statistically a likely-hood of slighter lower IQ in some that had a impact of 4 to 7 million dollars per year. For this impact, which is not actually measurable, we will spend hundreds of millions if not billions per year in mercury removal. We are free as a society to make that kind of decision. However, how is it possible that regulations were put into effect on that basis. Usually, they would be rejected as not effective. First, Congress had told EPA to regulate mercury. In other words, the scientific decision was largely preempted by Congress. However, EPA could still have determined that there were no cost-effective regulations. To avoid this, the EPA included the benefits in the analysis from measures such as scrubbers and bag houses that removed some mercury but were installed for and removed other pollutants with negative environmental effects. These benefits were already used to justify other regulations and should not have been counted again. This avoided the regulation of mercury from having a negative benefit/cost analysis in summary documents. The whole point is that we do not really know if there are measurable benefits from the money spent on mercury removal from power plant gases.
If the background mercury were a problem the human race would have gone extinct a long time ago. What were are adding with power is though to be only about 2% more a year and I would even question if that even close to the truth. It the amount of mercury outgassed from the oceans have been going on for ever, what we measure in the ground and water and in the animals is small. So there has to be a sink or something that naturally remove mercury the environment. WE do know it we collect it and dump it back into the environment those amount do not change much is the relative short time we been monitoring them. So our use of Mercury should be limited but what happening in coal fire plants are in all probability what coal fire plants are add in mercury is moot. Trying to control it is a waste of money and the human cost has little return. Raising the price of power does cost lives.
Good comment, Dick Kahle. I question the entire premise of mercury “control” as the eco-loons in the Sierra Club-directed EPA are only concerned about killing the coal industry & in general, increased regulations and controls. Their “risk studies” are based on these goals and cannot be trusted.
Had a similar mercury problem in the early nineties, but in a zinc smelter. For some reason the mercury wasn’t being captured by the scrubbers during summer. Drove us nuts.
Eventually we worked out the problem. In spring and summer algae would grow in the cooling water ponds. The algae then interacted with the mercury in the gas cleaning stage to magically prevent it from being scrubbed. The answer was an algicide added to the cooling pond. Fixed!
That may be a clue for coal plants with mercury capture issues. Do they have clean cooling water? Or is it full of biological agents that could combine to prevent the mercury from being scrubbed?
Good article.
Great to see the potential for reducing mercury emissions into the atmosphere, the only question that leaves though, if it is being captured into the fly ash, what happens to the ash? Fly ash is often dumped into pits and ponds and then forgotten about. At best ash is used to make products like cement but usually there is more ash than can be used for building materials. Also one has to wonder what the long term problems of having high levels of mercury in cement could create for workers if cutting concrete or demolishing structures built from such products.
Cameron Rogers
Having some mercury in a substance does not make it a “high level”. One has to consider the concentration and the bio-availability before making ratings.
All soil has mercury in it, like all food and clothes and cement and wood because it is natural. I have seen the same arguments about fly ash made about uranium in the ash.
The concentration of uranium in coal ash in Ulaanbaatar has been closely investigated because the coal comes from a uraniferous region (the whole of central and eastern Mongolia). The increase in radiation exposure over the background level is 0.5 microsieverts if you camp in a tent on top of the ash pond or ash dump. So it is a measurable change, but much less than walking into a building v.s. standing outside under the continuous shower of cosmic ray particles: 16 v.s. 23.
I read this article right before drifting off to sleep last night (I actually didn’t get all the way to the end. Finished it just now.) and so last night I had a dream about breaking open a mercury thermometer and pouring out the mercury and playing with it. I tried to play with it carefully, but I ended up getting it all over my hands and half of it ended up soaking deep into my old shag carpet (we do not have shag carpet in our house). Thanks WUWT for the dream material!
Ain’t that good news!