216 replies to this topic

[Tony Matthews]

But i am not one of these nay sayers to nuclear fuels just they are not the means to an end mealy a stepping stone that we should use with care to give us the time to develop far safer, efficient and ecologically sound ways of generating the power we need, than we do now.

The problem in the UK is that these 'stepping stones' have not been built, and probably won't now, due to our financial situation, so we will be reliant on fossil fuel for decades. If we don't dig up our remaining coal then we are at the mercy of outside suppliers. We are cornered, mainly due to weak government. As I said before, if France could do it, why couldn't we?

[McGuire]

Speaking of alternative energy sources, I saw something interesting today at a local prototyping firm: a hydrodynamic generator, or to be more precise, a 1/10 scale water tunnel model of one. The scale model was perhaps a meter in diameter and three or four meters long and looked somewhat like a jet engine nacelle, but with an impeller that resembled a wind tunnel prop. On the full-sized version the prop turns slowly enough that marine life can swim straight through without becoming fish sticks, I am told. It had just returned from preliminary water tunnel testing at a local university... ok so far, they report.

The idea is a small array of these could be deployed in river channels and so forth to harvest the energy in water current without totally redesigning the ecology as with traditional hydroelectric power (dams, man-made lakes, etc). Hadn't given "micro hydroelectric," as it is called, much thought or study until now and I have no idea of its practicality, but it is an interesting machine. Noted in passing: according to Wikipedia, hydroelectric provides around 20 percent of the world's electric power, and around 80 percent of its renewable power.

[Tony Matthews]

... hydroelectric provides around 20 percent of the world's electric power, and around 80 percent of its renewable power.

I've never really understood why, when there has been so much written about using wave- and tide energy to produce energy, and so many models and prototypes made, that we are seeing so many wid-farms blighting the countryside. At least you are guaranteed two tides a day- normally with only brief slack periods, and more often than not, waves. It couldn't be anything to do with subsidies, could it?

[Canuck]

I've never really understood why, when there has been so much written about using wave- and tide energy to produce energy, and so many models and prototypes made, that we are seeing so many wid-farms blighting the countryside. At least you are guaranteed two tides a day- normally with only brief slack periods, and more often than not, waves. It couldn't be anything to do with subsidies, could it?

Did I mention GE owns some of the premiere wind turbine technology...

[Tony Matthews]

Did I mention GE owns some of the premiere wind turbine technology...

You did indeed, Canuck, in an earlier eloquent post, which I should have re-read sooner! Very interesting...

[Canuck]

I'm jaded for sure, but I don't think it's in any way a stretch to say that corporations lobby governments to get what they want. Last night on our nationalized TV station (CBC), there was a story on alternative power in Canada, comparing us with Germany. They cited all sorts of examples in Germany of (primarily farmers) generating electricity from animal waste or solar or wind or a combination of and selling the excess onto the grid, using the heat from the generators to heat the farm etc etc. In one instance, the heat generated was used to heat 14 other homes (or so they say). As a contrast, Canada or more particularly Ontario is doing it's best to inhibit such things. In one case a rancher invested 1.1 million to build the generating system (again from animal waste) as per the Ontario Power Commission's outline. Then he was told he'd have to pay for the connection to the grid ($160,000). After it was built (but not connected) he was informed that because the connection was on public property, he had no choice but to sell the connection line back to the province for $1. And then they told him they didn't like his million dollar plant.

Ontario has 2 nuclear stations that generate roughly 50% of their power. They've suggested Ontario invest another 30 billion into upgrades and new construction. Go figure. The government is still paying for the Darlington facility that was way over-budget and won't be paid off until 2025. There's still a rider on your power bill for $25 every month. There are people trying to supply the grid with excess and yet they're effectively cock-blocked at every turn. As one interviewee put it - 30 billion on nuclear power is 30 billion not spent on solar or wind technology, not spent on developing those technologies.

[NeilR]

Speaking of alternative energy sources, I saw something interesting today at a local prototyping firm: a hydrodynamic generator, or to be more precise, a 1/10 scale water tunnel model of one. The scale model was perhaps a meter in diameter and three or four meters long and looked somewhat like a jet engine nacelle, but with an impeller that resembled a wind tunnel prop. On the full-sized version the prop turns slowly enough that marine life can swim straight through without becoming fish sticks, I am told. It had just returned from preliminary water tunnel testing at a local university... ok so far, they report.

The idea is a small array of these could be deployed in river channels and so forth to harvest the energy in water current without totally redesigning the ecology as with traditional hydroelectric power (dams, man-made lakes, etc). Hadn't given "micro hydroelectric," as it is called, much thought or study until now and I have no idea of its practicality, but it is an interesting machine. Noted in passing: according to Wikipedia, hydroelectric provides around 20 percent of the world's electric power, and around 80 percent of its renewable power.

Such things are already is use on some farms on the Goulburn river in Vic. I had a farm stay with my kids and the farmer who owned the property had made his own that lighted all his out buildings. Also made a sold a version that pumped water. I got the feeling he did not want anyone to know about the generator one...perhaps a tax on such things?

[Greg Locock]

tidal power is terrific, in many ways.

But it suffers the usual problems with marine installations - fouling is a huge deal.

The you have a bit of an issue getting the power from where it is to where you want it. That's easy enough to work out.

Wave power suffers a big problem - big waves.

I'm not sure whether wave power suffers the same variability problems as wind, but there are huge over power events.

[McGuire]

Such things are already is use on some farms on the Goulburn river in Vic. I had a farm stay with my kids and the farmer who owned the property had made his own that lighted all his out buildings. Also made a sold a version that pumped water. I got the feeling he did not want anyone to know about the generator one...perhaps a tax on such things?

I understand there are hundreds, perhaps thousands of them in use in rural areas of China.

[Tony Matthews]

I got the feeling he did not want anyone to know about the generator one...perhaps a tax on such things?

They know now!

[cheapracer]

I've never really understood why, when there has been so much written about using wave- and tide energy to produce energy, and so many models and prototypes made, that we are seeing so many wid-farms blighting the countryside. At least you are guaranteed two tides a day- normally with only brief slack periods, and more often than not, waves. It couldn't be anything to do with subsidies, could it?

Because many countries such as middle Africa (where tides are rare) are being supported with mega amounts of money from places such as China to develop infastructure for themselves including power - wind farms are seen to be a correct and green choice.

Being the culture they are and being the culture China is Government officials are pocketing huge amounts of money left right and center - good friend here has an order for 200 1 meg turbines at 1.8 mill each and the Prez of that African country wants 10% of that as do local high level officials to clear permits etc.

Big business, the result may be "Green" but thats not why it's happening.

Mind you my friend is deep into researching Nuclear Power station stuff too such as rods that can be made here if it swings that way because that will be a money spinner too.

[cheapracer]

I understand there are hundreds, perhaps thousands of them in use in rural areas of China.

No, possibly a spin by the China Gov to look good but there is a few big wind farms. They don't actually generate electricity, in fact they are large electric fans strategically placed to blow away coal fire smoke - thats the green part.

One thing that is huge here is solar water heaters - Xi An, better known to you Guys as the Terracotta Warriors city, looks like something from a science fiction book as literally every single house/building has a solar heater on the roof.

I like your picture of "Two Dogs" Tony

[Tony Matthews]

...middle Africa (where tides are rare) ...

I thought climate change would ensure that Central Africa has its share of tides and waves. I see you know my name, paleface...

[J. Edlund]

Having grown up in a small northern town where a sizeable percentage of the residents used wood stoves as their source of heat, I must say wood as a fuel has a number of drawbacks. Apart from the obvious inability to replenish as fast as we consume, pollution in cold environments is tremendous. In a town of 3500 people the smoke trapped between the ground and cloud cover could be tasted. Granted new technologies could reduce the particulate emissions and likely increase the overall efficiency so the mass per effective btu should go down as well.

Grunt is on the money as per my response. I'm all fairness to GE, they don't run the powerplants or the grids (or the appliances), they just build and sell them.

After a nasty gas-heater explosion, my grandmother converted her swimming pool to pipe-on-roof solar heat.

Completely off-topic: just watching "Grand Prix" on the classic
movie station. No idea what the story is but what a beautiful noise those cars make.

Biomass (wood and others) works better in larger scale for production of heat for district heating and electric power. It's easier to clean the flue gas in that scale, and the plant can be built a bit outside the most populated arear with higher chimneys. It's also easier to handle the ash produced that way. If also heat pumps are used to produce heat from the electricity in individual homes its possible to get more heat out of a kg of biomass than if it was used directly.

The big problem with your recycled fuel ideas are that some of the most dangerous by-products from fission reactors (Known as the minor actinides, which include Neptunium, Americium, and Curium, are very long-lived nuclides that cause serious concern when it comes to storing them for more than 100,000 years) can only be recycled via fast reactors and unfortunately there are only 3 of those in the world left operating and they are in France, Japan and India (Russia does have some in use as power units for Naval propulsion).
So all this so called recycled fuel is not really fuel at all right now due to not having the right fast neutron reactors available to use it.
Which means just like they do at Sellafield they end up storing radioactive material/future fuel which will remain dangerous for upto 300K years unless governments decide to build more fast reactors.
Lets not forget fast neutron reactors, however, have a terrible track record in safety and economics, and are not capable of solving the waste problem unless governments were prepared to waste trillions (yes trillions not billions) just to reduce the growing piles of spent fuel.
Nuclear fission based energy is not a long term solution at best it is something that we should grow out of quickly, just because it works and is useful short term until we develop far safer and more efficient forms of energy does not mean we should put all our eggs in that one basket.
As for transmutation you have the problems of fission products in the waste, including the long-lived and highly dangerous radionuclides technicium-99 and iodine-129 which remain dangerous for up to 10K years.
Which ever way you look at it there is no way using nuclear fuel results in safe levels of radiation in 400 years and even in best case scenarios leave mankind with a legacy lasting atleast 25 times as long.

But i am not one of these nay sayers to nuclear fuels just they are not the means to an end mealy a stepping stone that we should use with care to give us the time to develop far safer, efficient and ecologically sound ways of generating the power we need, than we do now. Yes its far better to use fission than fossil fuels, especially as they will run out in the not too distant future, but just because fussion is not going to be here tomorrow does not mean we should not push on as fast as we can to learn how, and just because teh solar derived powers sources will never supply 100% of our needs does not mean they are not worth investing in. Even 10% of our power coming from solar based is still 10% less from fossil fuels and i don't think anyone would say that was a bad thing, unless they worked for someone like BNFL.

Currently eleectricity production is expected to account for 40% of the global greenhouse gas emissions in 2020, and to 2050 electricity production is expected to quadruple. So economic means which can produce large amounts of electricity without fossil fuels - or large deforestations that will result in 'CO2 debts' that will take decades if not centuries to 'pay back' will be required.
We also need power plants that will deliver 24/7 and not only when the conditions are right, as with solar and wind. For this purpose we have few realistic options, with nuclear power being one.

When used nuclear fuel is recycled by reprocessing, current reprocessing using PUREX separate the uranium and the plutonium from the other elements that can't be used in lightwater reactors. The plutonium is mixed with depleted uranium (8% plutonium, 92% depleted uranium) which is then used as fuel. The reprocessed uranium, repU, can be sent sent back to enrichment and the enriched uranium can then be used as fuel; if stored it's treated as low level waste. The solution used in reprocessing is then dried which leaves all other radioactive elements. This waste is used for vitrification, where it bond with glass which seals it in a stable form. The melted glass is then poured into stainless steel containers which are sealed. Of course, it's also possible to extract certain isotoped which can be usefuel; americum, caesium, strontium and others have industrial use.

But there are better systems to recycle fuel and deal with waste under development. Of the used fuel, approx. 95.6% are uranium, 3% are stable or short lived fission products, 0.3% are strontium and cesium which decays in a few centuries, 0.1% are long lived iodine and technetium, 0.9% are plutonium and 0.1% are long lived actinides. Uranium can be treated as low level waste, or better, recycled. The fission products are easy to handle, which leaves the transuranics and long lived iodine and technetium. So, if transuranics plutonium, neptunium, americum and curium along with the long lived fission products technitium and iodine could be removed from the fuel, the radiation level would be below that of uranium ore after 1000 years of storage. That's the purpose of reprocessing processes like UREX+ demonstated by Argonne. The long lived isotopes can be transmutated, turning iodine-129 into non radioactive xenon for instance, and the transuranics are destroyed by fast reactors and Russia have demonstrated that these are possible with their BN-series of reactors. BN-350 and BN-600 demonstration plants, rated 350 MWe and 600 MWe.

BN-350 showed that a fast reactor could be operated with operational and maintenance costs similar to conventional light water reactors, although the capital costs were high, but that is not unsurprising given that it's a demonstation plant. The larger BN-600 have operated since 1980 with only minor incidents and the cost of electricity is about twice that of conventional reactors - something that should put the costs in the same region as wind power and still cheaper than solar and biomass.

As the fast reactors work they breed plutonium at a rate that exceeds their consumption rate. This plutonium can be used to start additional fast reactors or used as fuel in conventional reactors mixed with uranium. The fast reactors are then used to destoy transuranic waste from the light water reactors. This could be used to produce energy for thousands if not hundred thousands of years without emissions of greenhouse gases or toxic exhaust. Release of radionuclides would be insignificant compared to normal background radiation levels for people who live nearby a plant.

[demoing]

Biomass (wood and others) works better in larger scale for production of heat for district heating and electric power. It's easier to clean the flue gas in that scale, and the plant can be built a bit outside the most populated arear with higher chimneys. It's also easier to handle the ash produced that way. If also heat pumps are used to produce heat from the electricity in individual homes its possible to get more heat out of a kg of biomass than if it was used directly.



Currently eleectricity production is expected to account for 40% of the global greenhouse gas emissions in 2020, and to 2050 electricity production is expected to quadruple. So economic means which can produce large amounts of electricity without fossil fuels - or large deforestations that will result in 'CO2 debts' that will take decades if not centuries to 'pay back' will be required.
We also need power plants that will deliver 24/7 and not only when the conditions are right, as with solar and wind. For this purpose we have few realistic options, with nuclear power being one.

When used nuclear fuel is recycled by reprocessing, current reprocessing using PUREX separate the uranium and the plutonium from the other elements that can't be used in lightwater reactors. The plutonium is mixed with depleted uranium (8% plutonium, 92% depleted uranium) which is then used as fuel. The reprocessed uranium, repU, can be sent sent back to enrichment and the enriched uranium can then be used as fuel; if stored it's treated as low level waste. The solution used in reprocessing is then dried which leaves all other radioactive elements. This waste is used for vitrification, where it bond with glass which seals it in a stable form. The melted glass is then poured into stainless steel containers which are sealed. Of course, it's also possible to extract certain isotoped which can be usefuel; americum, caesium, strontium and others have industrial use.

But there are better systems to recycle fuel and deal with waste under development. Of the used fuel, approx. 95.6% are uranium, 3% are stable or short lived fission products, 0.3% are strontium and cesium which decays in a few centuries, 0.1% are long lived iodine and technetium, 0.9% are plutonium and 0.1% are long lived actinides. Uranium can be treated as low level waste, or better, recycled. The fission products are easy to handle, which leaves the transuranics and long lived iodine and technetium. So, if transuranics plutonium, neptunium, americum and curium along with the long lived fission products technitium and iodine could be removed from the fuel, the radiation level would be below that of uranium ore after 1000 years of storage. That's the purpose of reprocessing processes like UREX+ demonstated by Argonne. The long lived isotopes can be transmutated, turning iodine-129 into non radioactive xenon for instance, and the transuranics are destroyed by fast reactors and Russia have demonstrated that these are possible with their BN-series of reactors. BN-350 and BN-600 demonstration plants, rated 350 MWe and 600 MWe.

BN-350 showed that a fast reactor could be operated with operational and maintenance costs similar to conventional light water reactors, although the capital costs were high, but that is not unsurprising given that it's a demonstation plant. The larger BN-600 have operated since 1980 with only minor incidents and the cost of electricity is about twice that of conventional reactors - something that should put the costs in the same region as wind power and still cheaper than solar and biomass.

As the fast reactors work they breed plutonium at a rate that exceeds their consumption rate. This plutonium can be used to start additional fast reactors or used as fuel in conventional reactors mixed with uranium. The fast reactors are then used to destoy transuranic waste from the light water reactors. This could be used to produce energy for thousands if not hundred thousands of years without emissions of greenhouse gases or toxic exhaust. Release of radionuclides would be insignificant compared to normal background radiation levels for people who live nearby a plant.

Could is a great word when you ignore the fact we cant due to not having the fast neutron reactors. therefore any further if and buts are not relevant as its what's what matter and most nuclear fuel is not able to be disposed of via fast breeders du7e to not having them built and the fact it will take decades to build new units even if they started today.
It does make me wonder if you work for someone like BNFL due to your willingness to dismiss solar power as not able to deliver right now but then also your willingness to justify nuclear with future possibilities (as well as your correct information on a subject most fail to understand).
lets not forget the facts.
So far, almost 90,000 tonnes (of 290,000 t discharged) of used fuel from commercial power reactors has been reprocessed. Annual reprocessing capacity is now some 4000 tonnes per year for normal oxide fuels, but not all of it is operational.

Between now and 2030 some 400,000 tonnes of used fuel is expected to be generated worldwide, including 60,000 t in North America and 69,000 t in Europe.
Now allowing for the fact that reprocessing only reduces the waste to 20% of its former amount ( the other 80% being used as fuels which will in the end still end up as waste.)
that still leaves 200,000 tons not reprocessed along with the other 20,000 tons left over from reprocessing add to that the estimated extra 320,000 tons and we have 520,000 tonnes of UNPROCESSED nuclear waste as well as 100,000 tons of reprocessed waste. So by 2030 we the human race will have over 620,000 tonnes of medium/high level nuclear waste and approximately 620,000,000 tonnes of low level waste yes 620M tonnes which still remains dangerous for many years to come.
BNFL estimates fuel accounts for only 1% of the total radioactive waste from nuclear plants the other 99% mainly being low level from such things as protective clothing, wipes etc and decomissioning (certain areas)
Certainly far more than your ideal view would expect to have left laying around.
Lets not kid ourselves many countries have as their official policy to not recycle but instead they prefer to directly dispose of the spent fuel. Countries like America are currently reconsidering if they should reprocess.
Have a look at the list below to see which countries dont even consider reprocessing spent fuel to see how floored the idea of reprocessing is right now as the argument why nuclear is safe, clean and not building up a massive problem left for later generations to overcome.

Waste management for used fuel and HLW from nuclear power reactors
Country Policy Facilities and progress towards final repositories
Belgium Reprocessing

* Central waste storage at Dessel
* Underground laboratory established 1984 at Mol
* Construction of repository to begin about 2035

Canada Direct disposal

* Nuclear Waste Management Organisation set up 2002
* Deep geological repository confirmed as policy, retrievable
* Repository site search from 2009, planned for use 2025

China Reprocessing

* Central used fuel storage at LanZhou
* Repository site selection to be completed by 2020
* Underground research laboratory from 2020, disposal from 2050

Finland Direct disposal

* Program start 1983, two used fuel storages in operation
* Posiva Oy set up 1995 to implement deep geological disposal
* Underground research laboratory Onkalo under construction
* Repository planned from this, near Olkiluoto, open in 2020

France Reprocessing

* Underground rock laboratories in clay and granite
* Parliamentary confirmation in 2006 of deep geological disposal, containers to be retrievable and policy "reversible"
* Bure clay deposit is likely repository site to be licensed 2015, operating 2025

Germany Reprocessing
but moving to direct disposal

* Repository planning started 1973
* Used fuel storage at Ahaus and Gorleben salt dome
* Geological repository may be operational at Gorleben after 2025

India Reprocessing

* Research on deep geological disposal for HLW

Japan Reprocessing

* Underground laboratory at Mizunami in granite since 1996
* High-level waste storage facility at Rokkasho since 1995
* High-level waste storage approved for Mutsu from 2010
* NUMO set up 2000, site selection for deep geological repository under way to 2025, operation from 2035, retrievable

Russia Reprocessing

* Underground laboratory in granite or gneiss in Krasnoyarsk region from 2015, may evolve into repository
* Sites for final repository under investigation on Kola peninsula
* Various interim storage facilities in operation

South Korea Direct disposal

* Waste program confirmed 1998
* Central interim storage planned from 2016

Spain Direct disposal

* ENRESA established 1984, its plan accepted 1999
* Central interim storage probably at Trillo from 2010
* Research on deep geological disposal, decision after 2010

Sweden Direct disposal

* Central used fuel storage facility – CLAB – in operation since 1985
* Underground research laboratory at Aspo for HLW repository
* Osthammar site selected for repository (volunteered location)

Switzerland Reprocessing

* Central interim storage for HLW at Zwilag since 2001
* Central low & ILW storages operating since 1993
* Underground research laboratory for high-level waste repository at Grimsel since 1983
* Deep repository by 2020, containers to be retrievable

United Kingdom Reprocessing

* Low-level waste repository in operation since 1959
* HLW from reprocessing is vitrified and stored at Sellafield
* Repository location to be on basis of community agreement
* New NDA subsidiary to progress geological disposal

USA Direct disposal
but reconsidering

* DoE responsible for used fuel from 1998, $32 billion waste fund
* Considerable research and development on repository in welded tuffs at Yucca Mountain, Nevada
* 2002 decision that geological repository be at Yucca Mountain was countered politically in 2009

Biomass is not the dead end you seam to believe, the simple answer is ensuring you replant to ensure you remain carbon neutral, the key point is you dont just use bio fuels it is a part of a combined plan which yes includes nuclear, but must also include all other possible means available to mankind.
Brazil is a clear example of how biofuels can and do work well. they now are able to produce 50% of all the fuel they need to keep their vehicles on the road from biofuels and these biofuels are carbon neutral in under 12 months.

Edited by demoing, 05 May 2010 - 04:17.

[mariner]

May I add something as an accountatn rather than all the engineers here. There are three basic questions that have to be asked of renewables technology investment and they are not much different from most big investments - 1) Does it make financial sense , 2) does it make carbon sense and 3) what is the opportunity cost?

An investment has to pass 2) or it will not reduce atmospheric CO2, it has to pass test 1) or it can't be afforded and, as Greece is showing government's( at leasst western ones ) are approacing their borrowing limits so ROI matters. Question 3) is an stack ranking one but the cost of doing any project has to include the cost of not doing something else.

So to take an example the Uk government spent $10B building a high speed train line from London to the Channel Tunnel to link up with the French high speed line. It reduces journey times by 20 minutes. It is seen a "green " because it should reduce air travel so save Co2.

I do not know enough about the project to say how green it is but there are several basic factors to be analysed.

1) Building a new rail line causes a lot of extra CO2 as it involves digging huge holes with bulldozers, making and laying lots of concreate and smelting lots steel for rails etc. So you start with a carbon defict you have to offset later.

2) The train from London to Paris now produce more carbon as they go at 180 mph in England instead of 80 mph so power consumtion rises rapidly due to aero effects.

3) Whilst the French are 80% nuclear the UK is about 80% fossil on electricity so extra spped means extra carbon output.

factors 1) and 2) above mean the carbon cost is actualy worse but the good news is that some passengers have switched from plane to train. Clearly that saves some CO2.

The carbon calculation is how many people per train have left the plane - good news - versus the extra carbon from each tiain's higher speed and the allocation of the construction carbon deficit over however many train days you choose. Given the urgency of CO2 reduction that is probably less than 20 years.

Having done the carbon sums over 20 years then you can calculate the carbon return on the $10B, the last bit is the opportunity cost ranking of " was spending $10B on a high speed train better than say spending it on insulting X million homes.

I am not trying to "prove" the high speed invetment was a bad CO2 idea the point is only that the calculations are do-able but a bit complicated and every CO2 idea needs a similar analysis before implentation.

I fear that a lot of what is decided on does seem to lack any rigorous analysis because theings like trains and renewables are sen simply as "good " so we must do them.

[demoing]

May I add something as an accountatn rather than all the engineers here. There are three basic questions that have to be asked of renewables technology investment and they are not much different from most big investments - 1) Does it make financial sense , 2) does it make carbon sense and 3) what is the opportunity cost?

An investment has to pass 2) or it will not reduce atmospheric CO2, it has to pass test 1) or it can't be afforded and, as Greece is showing government's( at leasst western ones ) are approacing their borrowing limits so ROI matters. Question 3) is an stack ranking one but the cost of doing any project has to include the cost of not doing something else.

So to take an example the Uk government spent $10B building a high speed train line from London to the Channel Tunnel to link up with the French high speed line. It reduces journey times by 20 minutes. It is seen a "green " because it should reduce air travel so save Co2.

I do not know enough about the project to say how green it is but there are several basic factors to be analysed.

1) Building a new rail line causes a lot of extra CO2 as it involves digging huge holes with bulldozers, making and laying lots of concreate and smelting lots steel for rails etc. So you start with a carbon defict you have to offset later.

2) The train from London to Paris now produce more carbon as they go at 180 mph in England instead of 80 mph so power consumtion rises rapidly due to aero effects.

3) Whilst the French are 80% nuclear the UK is about 80% fossil on electricity so extra spped means extra carbon output.

factors 1) and 2) above mean the carbon cost is actualy worse but the good news is that some passengers have switched from plane to train. Clearly that saves some CO2.

The carbon calculation is how many people per train have left the plane - good news - versus the extra carbon from each tiain's higher speed and the allocation of the construction carbon deficit over however many train days you choose. Given the urgency of CO2 reduction that is probably less than 20 years.

Having done the carbon sums over 20 years then you can calculate the carbon return on the $10B, the last bit is the opportunity cost ranking of " was spending $10B on a high speed train better than say spending it on insulting X million homes.

I am not trying to "prove" the high speed invetment was a bad CO2 idea the point is only that the calculations are do-able but a bit complicated and every CO2 idea needs a similar analysis before implentation.

I fear that a lot of what is decided on does seem to lack any rigorous analysis because things like trains and renewables are sen simply as "good " so we must do them.

unfortunately i dont think that the new high speed extension from London was ever done as an environmental project.
It certainly was not marketed as such. I certainly remember it being marketed as the new highspeed way to travel from the UK into the heart of Europe.
No government does everything based on green credentials sometimes other things take precedence.
I agree it would certainly be a step in the right direction if all government proposals would assessed for their green credentials, but it never can be the only or even main criterion to judge everything by.
with the HSRL you would also need to add in all the ways the travellers used to get to Ashford before the link was finished to get a fairer idea of total CO2 cost/benefit is.
certainly it is clear that the link would be far greener if they reduced the speed but then they would lose passengers to jets.
One thing is clear no matter how much efficiency is lost to the high speeds it certainly saves CO2 against the jets that some people no longer take.