[Petrochemicals (OP)]

. Given unlimited refueling and servicing, are powerstations rendered worn out due to the time span of installed fuels ie years since commissioning or amount of operation of installed fuels, ie how much reaction has taken place?

[alancalverd]

Fuel rods are moved, removed and replaced cyclically depending on the design of the reactor. Fixed parts tend to wear or corrode  and AFAIK it is these elements that eventually become unsafe or uneconomic, but most UK reactors to date have been tested and re-licensed well beyond their original design life expectancy. 

Since nuclear power reactors are designed and funded to run continuously at near-maximum power, there isn't a lot of difference between  "wear and tear" and total energy output.   

[Petrochemicals (OP)]

If they are designed to run continuously, do they run continuously? I understand the new gas generation is designed to be a quick start operation to take up the demand shortfall, so nuclear plants are the backbone these days along with oil.

[alancalverd]

As far as possible, yes. That's the reason that electricity is cheap in the wee small hours. IIRC the optimum is to run a nuke at 80% of rated output for 90% of the time.

[acsinuk]

This shows what grid power is being generated  https://www.gridwatch.templar.co.uk/
If we stop using oil which long distance lorries require, as well as coal we will have to rely on wind, tidal and hydro as main sources of fuel which are not reliable enough to avoid black outs.
Nuclear is the best backup but we must also invest in pumped storage schemes to beat the peaks and gas turbines as a last resort.  We need to keep all our existing nuclear sites as for sure we are going to need them soon to stop climate change.

[alancalverd]

We've had quite a lot of discussion of pumped storage on this forum. Problem is that you'd have to flood an awful lot of Scotland  to store enough energy to run the country for 5 days (the usual duration of negligible wind conditions), and I doubt that 20 days worst-case (the summer of 1978 and the winter of 1952, IIRC) is feasible at all.

Why Scotland? Because England is too flat to be any use, and Wales is too small to be much help.

The most sensible experiment is going on in Orkney, where public transport and official vehicles are running on hydrogen.

Non-pumped hydroelectricity has already been exploited to the economic limit. It is very reliable, very flexible, but can only supply about 3% of UK demand because lots of people live on the big flat bit and the mountains are quite small. Norway is much better - mostly big mountains, with a small population living mostly on the coastal strip.   

Tidal power is absolutely predictable but (a) really screws up the environment (b) AFAIK it has only been demonstrated to work on a large scale in two places on the planet and (c) it happens when the sun and moon make it, not when you need it. It also suffers from the problem of criticality: you need very few, very large turbines, so if one stops working for any reason, you lose a large fraction of your power for a very long time (marine repairs are far more difficult than doing the same job on land).   
 

[Petrochemicals (OP)]

This shows what grid power is being generated  https://www.gridwatch.templar.co.uk/
If we stop using oil which long distance lorries require, as well as coal we will have to rely on wind, tidal and hydro as main sources of fuel which are not reliable enough to avoid black outs.
Nuclear is the best backup but we must also invest in pumped storage schemes to beat the peaks and gas turbines as a last resort.  We need to keep all our existing nuclear sites as for sure we are going to need them soon to stop climate change.

This was the motivation for the question really, if nuclear is non variable to the point of cost, wind solar etc is non reliable, another solution is needed for low times. I find gas is OK, or oil, we can produce oil synthetically.

[alancalverd]

Oil at present is far too valuable as transport fuel and chemical feedstock to be burned for electricity except in small emergency diesel generators for hospitals and the like.

Gas is the ideal makeup fuel to fill the gap between wind and demand but since Mrs Thtacher destroyed (not just closed, but destroyed a 200 year future asset for ever) the coal mines the principal source has been imports from politically volatile places like Russia. A lot of coal used to be turned into "town gas" which could be easily substituted for the methane in current use, but all is not lost since town gas was 50% hydrogen, so we already have the storage and distribution infrastructure for electrolytic hydrogen that was built 150 years ago and has been steadily updated ever since. 

[Petrochemicals (OP)]

I find gas to be the transport choice to be honest with you, hybrid gas
, Low pollution etc. Gas is so low pollutant there's no point doing electric cars when our electric mains comes from fossil fuels. Like you say methane was switched to quite easily so if needs be cars can use that.

[acsinuk]

Electric cars are required in cities to avoid pollution  but once outside on motorways then gas or petrol/diesel are the correct fuel as the vegetation, trees and grass can absorb the carbon dioxide and even produce food by photosynthesis for us to eat.  The very idea of making electric lorries is totally impractical   
In fact, I would go as far as to say the same applies to trains; diesel electric hybrids are ideal as they run electric in cities but convert to diesel once in the countryside.  Save HS2 a lot of infrastructure costs.

[Petrochemicals (OP)]

Electric cars are required in cities to avoid pollution  but once outside on motorways then gas or petrol/diesel are the correct fuel as the vegetation, trees and grass can absorb the carbon dioxide and even produce food by photosynthesis for us to eat.  The very idea of making electric lorries is totally impractical   
In fact, I would go as far as to say the same applies to trains; diesel electric hybrids are ideal as they run electric in cities but convert to diesel once in the countryside.  Save HS2 a lot of infrastructure costs.

Gas is fine in cities, whilst being aware hydrogen can be used for direct electrical power, if it could be used in the combustion engine too this would make transition easier. Petrol is not bad as long as it is clean refinement and the vehicle is maintained. Diesils where notorious for their discharge before the CO2 gang got hold of it and recommended it in the 2000s , in cities particularly it has been an utter killer failure.

It seems if you look you can find sources that support my view and counter it too. But from experience, diesel is awful. Gas I have always thought is best due to the fact it is easily mixed, unlike liquid which is a problem to refine and combust due to its nature. Yes you can heat liquid to vapour but it just doesn't seem to combust as cleanly and there always seems to be more contamination.

[alancalverd]

Saab ran a demonstration diesel engine whose exhaust was cleaner than its intake. Every particle of soot or droplet of unburned oil is wasted energy: the trick is to burn everything. This only happens in a very narrow range of speeds, so the ideal system is indeed diesel-electric, using a small diesel engine running at maximum efficiency to charge an electric buffer that handles acceleration and braking.

 

[Petrochemicals (OP)]

Saab ran a demonstration diesel engine whose exhaust was cleaner than its intake. Every particle of soot or droplet of unburned oil is wasted energy: the trick is to burn everything. This only happens in a very narrow range of speeds, so the ideal system is indeed diesel-electric, using a small diesel engine running at maximum efficiency to charge an electric buffer that handles acceleration and braking.

 

I have to ask about the fuel purity, any additives catalysts filters and scrubbers? It does sound pretty good for short notice generation.

I'm sure you could make all diesel cleaner by just adding a reburn chamber to burn all the exhaust gasses with added air, it works with wood combustion. Only thing is would be the engine would be larger and the efficiency less. I bet it still would not match a good methane or butane turbine engine.

[charles1948]

Saab ran a demonstration diesel engine whose exhaust was cleaner than its intake. Every particle of soot or droplet of unburned oil is wasted energy: the trick is to burn everything. This only happens in a very narrow range of speeds, so the ideal system is indeed diesel-electric, using a small diesel engine running at maximum efficiency to charge an electric buffer that handles acceleration and braking.

 

I have to ask about the fuel purity, any additives catalysts filters and scrubbers? It does sound pretty good for short notice generation.

I'm sure you could make all diesel cleaner by just adding a reburn chamber to burn all the exhaust gasses with added air, it works with wood combustion. Only thing is would be the engine would be larger and the efficiency less. I bet it still would not match a good methane or butane turbine engine.

Don't you think that diesel-engines are much more appealing scientifically.  They produce power by simple physical compression of fuel within the engine, to achieve combustion and energy-release.   Without needing an input of extraneous electrical energy, in the form of "spark-plugs". 

The beauty of diesel-engines is this: they produce power without any external energy input, other than the latent chemical energy contained within the fuel. 
 
Petrol-engines, by comparison, seem barbarous devices.  They won't work unless you stick an electric spark into them. Which seems an unnecessary complication, and offends against the purity of simplicity.

[alancalverd]

I agree. My early driving career was plagued with cars that wouldn't start because of finicky ignition systems that became more complicated over the years. The pathetic contact breaker and distributor was gradually replaced by a Hall-effect sensor and transistor inverter but it still all seemed to depend on things not getting wet, so I graduated to diesels. Problem there was that the old "tractor" mechanical pump and injector system was utterly reliable and worked beautifully at 2300 rpm but produced clouds of smoke when accelerating, so over the years it was replaced by increasingly sophisticated electronic gizmos that monitor everything and produce a clean burn at all loadings....until something goes just a tiny bit off color, when the entire system collapses in a coruscating display of warning lights and needs a garage computer to tell me what is actually wrong, except it might be something else because you have the beta software so we'd better replace all the (now very expensive) piezoelectric injectors.....

I (and many others) had high hopes for diesel aero engines. The reliability requirement is much more stringent and the rev range much lower than for cars, so nearly all small gasoline aero engines have two magnetos and twin spark plugs, by order of The Authorities - strange, expensive and heavy bits of kit that need lots of preventive maintenance. An aero diesel would burn Jet-A1, much cheaper, safer and easier to obtain than  AVGAS, but it's taken 20 years to produce anything that matches the reliability of gasoline, and they need water cooling!

[acsinuk]

Alan, not all petrol engines need water cooling; think of the VW Beetle and motor bikes.  But, I do agree that if increasing purity of exhaust gases involves advanced electronics then we are going over the top; as MOT should be restricted to road worthiness tests and not environmental niceties, in my view.  Next thing is we will be scrapping 5 year old low mileage cars that run perfectly well but just fail emissions test and replacement electronics components will cost £2,000 plus labour plus VAT.

[Bored chemist]

Alan, not all petrol engines need water cooling; think of the VW Beetle and motor bikes. 

Since he was talking about aircraft engines...

But, I do agree that if increasing purity of exhaust gases involves advanced electronics then we are going over the top; as MOT should be restricted to road worthiness tests and not environmental niceties, in my view.

"Air pollution from traffic kills 5000 a year in UK"
from
https://www.airclim.org/acidnews/air-pollution-traffic-kills-5000-year-uk
That's roughly three times as many as from road accidents.

Why do you want to make the death toll worse?

[alancalverd]

Air pollution from traffic kills 5000 a year in UK"

I've never seen an estimate based on postmortems or laboratory studies. Every estimate I've read just says "an estimate" by a committee. I'd be grateful for a lead to any actual science.

We do know that 1950s seasonal smog increased deaths from bronchitis and other acute respiratory disease but the problem with chronic "traffic" pollution is that its growth has been accompanied by an annual increase in life expectancy.

Recent headlines correctly quoted a coroner as concluding that a girl's death was related to air pollution but she was known to be severely asthmatic and there was no suggestion that the other 30,000 people living in the same area  were prone to early demise.

[alancalverd]

Alan, not all petrol engines need water cooling

Absolutely. Which is why aircraft engines below 2000 horsepower are mostly aircooled. The horizontally opposed types up to about 500 hp "flat sixes" all look like big VW beetles and bigger beasts tend to be 9 or 11 cylinder radials or stacked multiples of 7 cylinders. Big liquid-cooled gasoline engines like the Merlin were preferred for fighters because they are more flexible - you can go from "loiter" to "combat" without worrying too much about oil temperatures, but bombers and freighters spend most of their time in cruise at constant speed and altitude so the simplicity of an aircooled motor gives you more payload.