Is nuclear power really green?

[saveasteading]

I know it makes radiation and is dangerous but I've just twigged something. Boffins comments sought.

 

 

Wind, sun and water all provide a fairly closed loop of extracting energy from current nature and releasing it as heat almost in real time. Effect on the planet fairly small.(?)

 

But can a boffin confirm that nuclear does not have this benefit?

 

Oil coal and gas are energy stored over millions of years , being released over tens. Bad.

 

Burning timber from commercial forests is the sun's resources collected over a few decades.

 

But Nuclear energy was created in the Big Bang, quite a whike ago, so is adding to heat gain in a sudden manner and is not "renewable". Bad.

 

 

 

So we should only use sun, wind, hydro and tides, but perhaps some timber from waste, and from rubbish.

[-rick-]

12 minutes ago, saveasteading said:

But Nuclear energy was created in the Big Bang, quite a whike ago, so is adding to heat gain in a sudden manner and is not "renewable". Bad.

 

Firstly, I think we are talking about renewable in the sense of 'planet earth has limited supplies'. Once we go off planet the resources available are vast (but the technology required to access them are also a long way off).

 

If we are just worried about planet earth then the available resources for nuclear is more than enough to keep us going for a very long time without worrying about depletion. If nuclear was cheap and we had well developed end-of-life plans I don't see much issue with it given current safety standards. But it's not cheap and we don't have well developed end of life plans so I'm not a huge fan based on that. Having said that, if the safety aspect can be dealt with putting small nuclear on very big ships would eliminate a lot of emissions and potentially lower costs for everyone.

 

Using nuclear generation produces heat and some have questioned whether that heat output is a negative given global warming. My understanding is that the amount of energy used/heat produced by human activity is absolutely tiny compared to the amount of heat/energy output into planet earth from the sun and it's therefore not remotely a concern. Maybe a concern in local areas (heating seawater locally, producing fog in local valleys, etc). But these are the same as any other steam using power source (gas, coal, wood, etc).

[jack]

8 minutes ago, -rick- said:

Using nuclear generation produces heat and some have questioned whether that heat output is a negative given global warming. My understanding is that the amount of energy used/heat produced by human activity is absolutely tiny compared to the amount of heat/energy output into planet earth from the sun and it's therefore not remotely a concern. Maybe a concern in local areas (heating seawater locally, producing fog in local valleys, etc). But these are the same as any other steam using power source (gas, coal, wood, etc).

 

100% agree.

[saveasteading]

30 minutes ago, -rick- said:

renewable in the sense of 'planet earth has limited supplies'.

I'm not really . I'm being perhaps being lazy and vague. I mean readily renewable, not laid down millions of years ago.

 

32 minutes ago, -rick- said:

not remotely a concern.

Not my understanding. Unless the climate change is all down to pollution rather than energy release.

 

Small nuclear sounds worrying. If VW, Dacia (and some others) start putting it in cars we have to worry a lot about the quality control and back-lot mechanics. (Easier to express for cars than with ships)

[LnP]

2 minutes ago, saveasteading said:

 

Not my understanding. Unless the climate change is all down to pollution rather than energy release.

 

Climate change is due to the changing chemical composition of the atmosphere, which causes heat from the sun to be trapped and the planet to heat up. It's not due to the heat which is released from human activity.

[JohnMo]

35 minutes ago, -rick- said:

we don't have well developed end of life plans so I'm not a huge fan

Not sure there are any long term plans except concrete and lead lining of fuel waste, components removed during the plant life treated in a similar manner. Then decommissioning taken several lifetimes.

 

Impact on the planet ignoring the above is pretty small, you use the heat to make steam that drives a steam turbine or two. There is no combustion by product that leads to global warming - just super heated water, used in the turbines.

 

Renewable - no, radiation is from a fuel source it gets depleted and converted to a waste product. It happens the waste product is very dangerous to all life.

[JohnMo]

6 minutes ago, saveasteading said:

Small nuclear sounds worrying. If VW, Dacia (and some others) start putting it in cars

It's not that small as you need a steam plant to go with it. So would be a car a 10 Tonne trailer.

[-rick-]

3 minutes ago, saveasteading said:

Not my understanding. Unless the climate change is all down to pollution rather than energy release.

 

Solar is 1000W/m2. Work out how many m2 of the planet there is and calculate the total amount of energy (obv not all planet is exposed to sun at same times). I'm sure an AI will help do this.

 

Then calulate the amount of energy we put out. It's a very very tiny fraction of total energy.

 

3 minutes ago, saveasteading said:

Small nuclear sounds worrying. If VW, Dacia (and some others) start putting it in cars we have to worry a lot about the quality control and back-lot mechanics. (Easier to express for cars than with ships)

 

Haha here comes the jetsons!

 

No, not gonna be in cars any time soon (or trucks). Batteries are perfectly fine for those. Ships, and only very big ships, there are are really two options to power them that don't burn vast quantities of fuel.

 

1. Sail

2. Nuclear

 

Some ships are trying out sail and modern systems are aimed at reducing fuel burn not eliminating it. A useful contribution but not game changing. Ships have a schedule to keep so can't be waiting around for the right wind conditions. Nuclear on those ships is not crazy. They already have largeish crews with dedicated specialist engineers on board. The type of nuclear talked about for those ships is the 60-100MW range, so tiny comparitively. Likely to be an inherently safe design that is packaged as a module and craned on/off for maintenance, etc.

[SteamyTea]

Shame I am work at the moment.

When I studied RE we looked at all firms of electricity production. Nuclear, when generating is very low CO₂ generation. The long term storage is a problem, mainly political, latest idea is to bury it in the Irish Sea mudstone. It may happen.

There is a question mark over the security of uranium supplies, processing, transport and storage.

 

Regarding the excess thermal energy heating the atmosphere, not really. But local heating is a problem, as is excess air temperature. A French reactor was on reduced power because it could not get enough cooling. All large thermal plants cab suffer from that.

 

The main thing is to reduce the CO_2e gasses and particulates. These are the main problems.

CO_2e gasses do not act like a blanket, depending on which model used to calculate, it really just allows more energy to be stored kinetically (temperature is the mean free path speed of molecules after all).

[Beelbeebub]

The thermal plant (fossil fuel or nuclear) issue during hot weather is more regulatory than technical.

 

These systems have delta T's of several hundred degrees, the increace of 10nornsondegrees at the cold side isn't a major technical problem. 

 

But all thermal plants have limits on the temperature of the "used" cooling water. This is for ecological reasons, if you started dumping thousands of m3 an hour af 80C water into a river or the sea you'd kill everything downstream. There are also limits on the amount of water they can take. 

 

During hot weather there is a much smaller window between the maximum water temperature leaving and the regulatory limit. 

 

This is particularly acute for river cooled plants that may also experience low river flows at the same time. 

 

 

[saveasteading]

19 hours ago, SteamyTea said:

When I studied RE we looked at all firms of electricity production.

Religious Education? 

I've seen the pictures of God sending lightning bolts from his fingers, but no wind turbines.

[saveasteading]

20 hours ago, JohnMo said:

It's not that small

In my mind is that I had a 'special' visit to Dungeness and the hall was vast... it made me think of James Bond final scenes but bigger.

Also that the cooling water was jettisoned at sea, making about 100m circle of turbulent hot water. That is a mile out in the English channel so would kill any river surely.

 

Good explanations all, and I am now a little wiser.

[SteamyTea]

35 minutes ago, saveasteading said:

Religious Education

Well according to some it is treated the same by 'the believers'

 

 

[MikeSharp01]

21 hours ago, -rick- said:

Some ships are trying out sail and modern systems are aimed at reducing fuel burn not eliminating it. A useful contribution but not game changing. Ships have a schedule to keep so can't be waiting around for the right wind conditions. Nuclear on those ships is not crazy. They already have largeish crews with dedicated specialist engineers on board. The type of nuclear talked about for those ships is the 60-100MW range, so tiny comparatively. Likely to be an inherently safe design that is packaged as a module and craned on/off for maintenance, etc.

People get confused about small nuclear and tend to say "they have them in nuclear submarines so why not take that technology and pop it into ships" - sounds like a fair plan until you realise that the fuel for these subs is weapons grade (95% enriched) to reduce / remove refuelling demands to 30 years plus - refuelling less highly enriched 10-20% is very complex and expensive needing specialist facilities. We have limitations treaties on the fuel so that's a limiting factor as well. Also many countries do not allow nuclear powered ships to dock for safety reasons, you need greater security for the ship when travelling and much better trained crews.  

[JohnMo]

42 minutes ago, saveasteading said:

Also that the cooling water was jettisoned at sea

Basically steam is made it drives steam turbine that drive a generator to make electricity. The steam turbine strips the energy from the steam making it a low quality steam. They are basically taking seawater in, passing through one side of a heat exchanger this used to cool the low quality steam back to liquid on the other side. The then hot cooling water goes back to the sea. The turbine water/steam goes around in circles just like your heating system.

 

On a different circuit high pressure water passes through the reactor core taking heat. An intermediate loop extracts that heat to heat the steam circuit.

 

So you have several layer of seperation from the reactor to the sea

[saveasteading]

31 minutes ago, JohnMo said:

several layer of seperation from the reactor to the sea

I didn't think it was reactive but that the heat will kill a river apart from algae etc.

Around the Dungeness maelstrom were hundreds of seagulls after fish that are attracted to the warm water.

This is a dormant station so presumably was on tick over.

There are tales of Mediterranean creatures being found on south coast beaches bug I've no idea if there is any link.