Just to put some extra numbers on the toxicity of coal: It's estimated that 21% of global mercury emissions currently come from coal burning (https://www.epa.gov/international-cooperation/mercury-emissions-global-context). And, as opposed to some other toxicants, mercury can travel long distances. It can start as vapours at the power plant, then get into rivers, and end up in the marine food chain. Coal waste is not "just ash" as many people believe.
Why are we only talking about coal ash for the mass of waste?
Surely the paper should have included the mass of the CO2 and NOx etc released into the atmosphere.
Talking about overflowing landfills is a deliberate attempt to mislead, and pervert the conversation around renewables. They should not have stopped at correcting that misinformation about the solid waste created by renewables...
The bigger problem is surely with the waste combustion releases to the atmosphere. That’s the biggest waste stream of the lot surely.
Of course, the climate and air pollution issues of fossil fuels are quite obvious (and in this case didn't really need to be restated).
Here I focused on the arguments of the solid waste generated, which is a common pushback against low-carbon technologies. I think it's fine and fair to take on each of these components one-by-one to understand what the magnitude of different problems are (not least to drive work on better solutions).
Sure, and of course the original paper took the same approach.., but still I think when confronted with the what aboutism of waste solar panels…it’s probably fair to add the mass of CO2 and NOx to the cubes (or bar chart) for the waste created by coal power. It’s a waste and it needs dealing with.
By the way, don't fossil-fuel—and nuclear, for that matter—power plants generate waste in the form of discarded parts, too? Why is this never mentioned? Perhaps because it's insignificant compared with the coal ash, like solar- and wind-power waste are?
First of all: I would like to express my deep gratitude for the consistent quality of this newsletter and the posts. It is taking on difficult questions and aims to provide qualified answers. If society would work in the same the world would be a better place.
Secondly: This is such a strong example of why 3D charts are (a) hard to read and (b) usually misleading that it should be in a text book.
Thanks for another great post Hannah. Entirely understand that nuclear waste was a bigger topic than realistically can be addressed in the post. The cost of decommissioning nuclear plants is eye watering. Government published estimates for the UK are already pretty astounding, but some suggest they are an understatement.
Still it’s interesting to put scale on these issues. I’m sure you’ve already read many of the papers I have on this. While decommissioning nuclear will be hideously expensive- Coal’s waste production of course absolutely dwarfs nuclear and its harmful health impacts and deaths are on a different scale. Burning coal for power even releases more radioactive material than nuclear power simply because of the amount of material involved in coal.
But, "at least ten times less than other e-waste streams; about 300 times less than coal ash; and about 500 times less than municipal waste."
10% less, is 90% of prior level; 75% less is 25% of prior level, 90% less is 10% of prior level. Anything more than 100% less (such as ten times, 300 times, 500 times) implies a negative quantity and is meaningless.
If you are trying to say 'less than 1 tenth' or 'one three hundredth' or 'one five hundredth' (probably better to say 99.7% less, or 99.5% less) please do so.
Great post Hannah! Learned so much especially on the calculation of waste per energy generated. In footnote 3, should it say "a standard 400W solar panel" instead of MW?
Hannah, Here's some information about radioactive waste from fission power, in a presentation I gave earlier this year. It also covers misunderstandings of the toxicity of spent fuel, and ends with a pitch for more nuclear power. Bob Hargraves
An excellent post, as ever. I've seen fly ash from power generation referred to as toxic on a number of occasions. But the classification as such seems to be primarily in the US. Across much of the rest of the world, fly ash is used to decarbonise concrete production (replacing 20% of Portland cement in concrete will reduce the carbon footprint by about 15%).
I know very little about coal waste. Is fly ash the main component of coal burning waste?
I asked ChatGPT and got this, is that accurate?
Fly Ash: This is the lighter, fine particles that are captured from the flue gases. It constitutes about 60-70% of the total ash produced in the combustion process.
Bottom Ash: This is the coarser, heavier material that settles at the bottom of the furnace. Bottom ash typically makes up about 20-30% of the total ash.
Boiler Slag: This is a molten form of bottom ash that is collected at the base of the slag tap and cyclone type furnaces. It constitutes a smaller percentage of the total waste, usually less than 10%.
However, I was disappointed you didn't discuss nuclear waste toxicity & risk above. I've often wondered how it compares to coal ash. I would also like to know how long it takes for nuclear waste to degrade to less powerful radioactive waste - How long will it be for the spent fuel to be a major risk if/when containment leaks. 100 years? 100,000? I don't have good sense of relative risks... have you ever covered that?
Nuclear waste is a very big (and controversial topic), and trying to squeeze it into a broader post would not do it justice. No one would be left satisfied with my answer.
quibble on footnote 3 (Solar).. "average 400 MW solar panel". Does this mean "average 400 W" solar panel? At 22kg, seems likely. Which I suppose _might_ get you close to 0.5 MWh/year.. at least in a sunnier part of the world than where I live (where working #s are 1W solar capacity =~ 1kwh/year). But, ok, ballpark.
One megawatt-hour of coal electricity produces 89 kg of ashes and 1000 kg of CO2. The big problem is the CO2.
Also the number for nuclear seems wrong to me, a MWh of nuclear electricity produces 0.031 kilograms of fuel waste but also 0.760 kg of concrete waste and 0.160 kg of steel.
Yes, the obvious and biggest issues with fossil fuels are the climate and local air pollution impacts. But I also think it's useful to look at the numbers on other forms of waste (not least because they're often used to argue against renewables).
On nuclear: that principle also applies to other technologies (concrete and steel for solar, wind, coal or nuclear plants). It's not too far from the question I answered in a recent newsletter about the 'total material requirements' of the energy transition: https://www.sustainabilitybynumbers.com/p/energy-transition-materials
My problem is that I don't understand the terms of the comparison. We are not speaking about waste in general, or it would include the CO2; we are not speaking about solid waste, or it would include steel and concrete from solar and wind; we are not speaking about special waste, or it would include the neutron activated steel from a nuclear reactor.
It is interesting to know how much ash comes with a MW of coal electricity but why do you want to compare that mass with the ones of wind turbine's blades or spent nuclear fuel?
I have the same curiosity about the waste profile of gas as it is also the leading competitor for electric generation in the US as well. The use of "natural" gas actually has quite a bit of solid and liquid waste associated with exploration and extraction, some of it quite hazardous. When natural gas is extracted, it is often accompanied by various contaminants, including heavy metals, radioactive materials, and volatile organic compounds (VOCs). These contaminants, along with the water used in the extraction process, result in waste known as produced water. Fracking, particularly, may utilize tens of thousands of gallons of toxic additives for each well resulting in even larger volumes of toxic drilling muds and fluids. I am guessing that a full analysis of the gas life cycle would result in a significant waste profile far beyond the renewables EOL material residues. https://www.nrdc.org/stories/fracking-101#why-ishttps://www.epa.gov/hw/management-oil-and-gas-exploration-and-production-wastehttps://www.ucsusa.org/resources/environmental-impacts-natural-gas
Very interesting. The metric of kg waste per kWh for nuclear is very low, but I wonder if his is a fair metric. With wind generation, and solar, is it not the case that you have taken into account the vast majority of material required to generate the power. But there is also the mass of the overall plant (concrete buildings, turbines etc) to consider. I suspect that even taking it into account, nuclear would be a winner by your metric, but maybe this material should be included. My own initial estimate of the mass of concrete used to build just the core of a 500MW nuclear reactor is approx 105 x 10^6 kg (A cylinder 60m high, perimeter 200m, 4m thick => 60m *4m *200m*2.2*10E3 tonnes per cubic meter). Amortized over an estimated 25 year life, this would be a cost of 4,200 tonnes per year. This amount is an order of magnitude higher than the nuclear fuel itself.
You might not need to estimate. EDF have published a few numbers for the Hinckley point C plant. I believe they have said how much concrete it will need. There’s a lot of data published from various sources to work with.
Thanks for the suggestion, Paul. It seems I was, at least, in the right order of magnitude. The EDF site documents (May 28, 2020) that the base for the second reactor was 49,000 tonnes. And I think there was another 20,000 tonnes in the water cooling tunnel ; though perhaps the tunnel could be used for Hinkley E and/or F so its life may be more than 25 years. But the 49,000 tonnes above is JUST the base - there must be plenty more concrete on the site. otoh, each reactor is a 1,600MW - much bigger than my estimate. So no cigar for me, but I am feeling pretty chuffed!
Dear Anna, thank you very much for your articles which has been quite heplful to gain insight on waste arising out of renewables and other sources.
I have reviewed your article and i have difficulty in finding 1.67 kg/Mwh for solar PVs under the circumstances of 22 kg , 400 Mw and %15 capacity factor.Can you please revisit your calculation.
Apologies - the 400MW in the footnote was a typo: it was supposed to be 400W.
Was that what was leading to the confusion? In the footnote I have laid out the series of calculations and assumptions. But do let me know if you spot an error so that I can correct it!
Just to put some extra numbers on the toxicity of coal: It's estimated that 21% of global mercury emissions currently come from coal burning (https://www.epa.gov/international-cooperation/mercury-emissions-global-context). And, as opposed to some other toxicants, mercury can travel long distances. It can start as vapours at the power plant, then get into rivers, and end up in the marine food chain. Coal waste is not "just ash" as many people believe.
Hang on a minute.
Why are we only talking about coal ash for the mass of waste?
Surely the paper should have included the mass of the CO2 and NOx etc released into the atmosphere.
Talking about overflowing landfills is a deliberate attempt to mislead, and pervert the conversation around renewables. They should not have stopped at correcting that misinformation about the solid waste created by renewables...
The bigger problem is surely with the waste combustion releases to the atmosphere. That’s the biggest waste stream of the lot surely.
Of course, the climate and air pollution issues of fossil fuels are quite obvious (and in this case didn't really need to be restated).
Here I focused on the arguments of the solid waste generated, which is a common pushback against low-carbon technologies. I think it's fine and fair to take on each of these components one-by-one to understand what the magnitude of different problems are (not least to drive work on better solutions).
Sure, and of course the original paper took the same approach.., but still I think when confronted with the what aboutism of waste solar panels…it’s probably fair to add the mass of CO2 and NOx to the cubes (or bar chart) for the waste created by coal power. It’s a waste and it needs dealing with.
By the way, don't fossil-fuel—and nuclear, for that matter—power plants generate waste in the form of discarded parts, too? Why is this never mentioned? Perhaps because it's insignificant compared with the coal ash, like solar- and wind-power waste are?
First of all: I would like to express my deep gratitude for the consistent quality of this newsletter and the posts. It is taking on difficult questions and aims to provide qualified answers. If society would work in the same the world would be a better place.
Secondly: This is such a strong example of why 3D charts are (a) hard to read and (b) usually misleading that it should be in a text book.
Thank You Hannah for the work you do.
This is rapidly turning into one of my favorite substacks! This one was particularly enlightening.
Thanks for another great post Hannah. Entirely understand that nuclear waste was a bigger topic than realistically can be addressed in the post. The cost of decommissioning nuclear plants is eye watering. Government published estimates for the UK are already pretty astounding, but some suggest they are an understatement.
Still it’s interesting to put scale on these issues. I’m sure you’ve already read many of the papers I have on this. While decommissioning nuclear will be hideously expensive- Coal’s waste production of course absolutely dwarfs nuclear and its harmful health impacts and deaths are on a different scale. Burning coal for power even releases more radioactive material than nuclear power simply because of the amount of material involved in coal.
Thank you for an informative post.
But, "at least ten times less than other e-waste streams; about 300 times less than coal ash; and about 500 times less than municipal waste."
10% less, is 90% of prior level; 75% less is 25% of prior level, 90% less is 10% of prior level. Anything more than 100% less (such as ten times, 300 times, 500 times) implies a negative quantity and is meaningless.
If you are trying to say 'less than 1 tenth' or 'one three hundredth' or 'one five hundredth' (probably better to say 99.7% less, or 99.5% less) please do so.
Thanks very much much for the feedback.
You're right on the language – I've tried to make it clearer now.
Great post Hannah! Learned so much especially on the calculation of waste per energy generated. In footnote 3, should it say "a standard 400W solar panel" instead of MW?
Yes, thank you! I fixed it now.
I absolutely love this newsletter!! Appreciate the work you do so much.
Hannah, Here's some information about radioactive waste from fission power, in a presentation I gave earlier this year. It also covers misunderstandings of the toxicity of spent fuel, and ends with a pitch for more nuclear power. Bob Hargraves
https://hargraves.s3.amazonaws.com/KendalNuclear.pdf
Thank you very much – I'll take a look.
Hopefully get the time to do a bigger piece on nuclear waste in the future.
An excellent post, as ever. I've seen fly ash from power generation referred to as toxic on a number of occasions. But the classification as such seems to be primarily in the US. Across much of the rest of the world, fly ash is used to decarbonise concrete production (replacing 20% of Portland cement in concrete will reduce the carbon footprint by about 15%).
I know very little about coal waste. Is fly ash the main component of coal burning waste?
I asked ChatGPT and got this, is that accurate?
Fly Ash: This is the lighter, fine particles that are captured from the flue gases. It constitutes about 60-70% of the total ash produced in the combustion process.
Bottom Ash: This is the coarser, heavier material that settles at the bottom of the furnace. Bottom ash typically makes up about 20-30% of the total ash.
Boiler Slag: This is a molten form of bottom ash that is collected at the base of the slag tap and cyclone type furnaces. It constitutes a smaller percentage of the total waste, usually less than 10%.
Hannah - really enjoying your work :)
However, I was disappointed you didn't discuss nuclear waste toxicity & risk above. I've often wondered how it compares to coal ash. I would also like to know how long it takes for nuclear waste to degrade to less powerful radioactive waste - How long will it be for the spent fuel to be a major risk if/when containment leaks. 100 years? 100,000? I don't have good sense of relative risks... have you ever covered that?
I will!
Nuclear waste is a very big (and controversial topic), and trying to squeeze it into a broader post would not do it justice. No one would be left satisfied with my answer.
Yup, makes sense - Thanks. I look forward to reading it!
quibble on footnote 3 (Solar).. "average 400 MW solar panel". Does this mean "average 400 W" solar panel? At 22kg, seems likely. Which I suppose _might_ get you close to 0.5 MWh/year.. at least in a sunnier part of the world than where I live (where working #s are 1W solar capacity =~ 1kwh/year). But, ok, ballpark.
ack! Sorry. others already quibbled. Ignore.
Thanks, yes – it was a typo in the footnote.
400W solar panel, not 400MW.
One megawatt-hour of coal electricity produces 89 kg of ashes and 1000 kg of CO2. The big problem is the CO2.
Also the number for nuclear seems wrong to me, a MWh of nuclear electricity produces 0.031 kilograms of fuel waste but also 0.760 kg of concrete waste and 0.160 kg of steel.
The nuclear fuel waste is a tiny fraction of the nuclear fuel: https://thoughtscapism.files.wordpress.com/2017/11/materials-throughput-energy.jpeg
Thanks!
Yes, the obvious and biggest issues with fossil fuels are the climate and local air pollution impacts. But I also think it's useful to look at the numbers on other forms of waste (not least because they're often used to argue against renewables).
On nuclear: that principle also applies to other technologies (concrete and steel for solar, wind, coal or nuclear plants). It's not too far from the question I answered in a recent newsletter about the 'total material requirements' of the energy transition: https://www.sustainabilitybynumbers.com/p/energy-transition-materials
My problem is that I don't understand the terms of the comparison. We are not speaking about waste in general, or it would include the CO2; we are not speaking about solid waste, or it would include steel and concrete from solar and wind; we are not speaking about special waste, or it would include the neutron activated steel from a nuclear reactor.
It is interesting to know how much ash comes with a MW of coal electricity but why do you want to compare that mass with the ones of wind turbine's blades or spent nuclear fuel?
Excellent write up!
I have the same curiosity about the waste profile of gas as it is also the leading competitor for electric generation in the US as well. The use of "natural" gas actually has quite a bit of solid and liquid waste associated with exploration and extraction, some of it quite hazardous. When natural gas is extracted, it is often accompanied by various contaminants, including heavy metals, radioactive materials, and volatile organic compounds (VOCs). These contaminants, along with the water used in the extraction process, result in waste known as produced water. Fracking, particularly, may utilize tens of thousands of gallons of toxic additives for each well resulting in even larger volumes of toxic drilling muds and fluids. I am guessing that a full analysis of the gas life cycle would result in a significant waste profile far beyond the renewables EOL material residues. https://www.nrdc.org/stories/fracking-101#why-is https://www.epa.gov/hw/management-oil-and-gas-exploration-and-production-waste https://www.ucsusa.org/resources/environmental-impacts-natural-gas
Very interesting. The metric of kg waste per kWh for nuclear is very low, but I wonder if his is a fair metric. With wind generation, and solar, is it not the case that you have taken into account the vast majority of material required to generate the power. But there is also the mass of the overall plant (concrete buildings, turbines etc) to consider. I suspect that even taking it into account, nuclear would be a winner by your metric, but maybe this material should be included. My own initial estimate of the mass of concrete used to build just the core of a 500MW nuclear reactor is approx 105 x 10^6 kg (A cylinder 60m high, perimeter 200m, 4m thick => 60m *4m *200m*2.2*10E3 tonnes per cubic meter). Amortized over an estimated 25 year life, this would be a cost of 4,200 tonnes per year. This amount is an order of magnitude higher than the nuclear fuel itself.
You might not need to estimate. EDF have published a few numbers for the Hinckley point C plant. I believe they have said how much concrete it will need. There’s a lot of data published from various sources to work with.
Thanks for the suggestion, Paul. It seems I was, at least, in the right order of magnitude. The EDF site documents (May 28, 2020) that the base for the second reactor was 49,000 tonnes. And I think there was another 20,000 tonnes in the water cooling tunnel ; though perhaps the tunnel could be used for Hinkley E and/or F so its life may be more than 25 years. But the 49,000 tonnes above is JUST the base - there must be plenty more concrete on the site. otoh, each reactor is a 1,600MW - much bigger than my estimate. So no cigar for me, but I am feeling pretty chuffed!
Dear Anna, thank you very much for your articles which has been quite heplful to gain insight on waste arising out of renewables and other sources.
I have reviewed your article and i have difficulty in finding 1.67 kg/Mwh for solar PVs under the circumstances of 22 kg , 400 Mw and %15 capacity factor.Can you please revisit your calculation.
Hi Levent. Thank you!
Apologies - the 400MW in the footnote was a typo: it was supposed to be 400W.
Was that what was leading to the confusion? In the footnote I have laid out the series of calculations and assumptions. But do let me know if you spot an error so that I can correct it!