Why we need "Net zero"

[Beelbeebub]

1 hour ago, BotusBuild said:

• Base load of Nuclear (fission to start, maybe fusion in the long term (maybe more than 20 years 😁))
• Base load of Gas Turbines with 90 day storage
• Hydro (as in Wales)
• Tidal
• Solar
• Wind

I would say the gas should be peaker/backup load not any kind of base load. 

[-rick-]

Just now, Beelbeebub said:

I would say the gas should be peaker/backup load not any kind of base load. 

 

This and long term this is where hydrogen can be useful. Use excess solar during the summer to make hydrogen, store it for peaker use in winter. All done in one site, no need to pipe it anywhere.

 

Other note is that batteries can fill all the short term responsive capacity that peaker/stored hyrdo used to do. The only thing batteries can't really do is longer duration peaker load. ie, those 1-2week super cold winter periods.

[Beelbeebub]

1 hour ago, Oz07 said:

Tbf im not really on about re building our network based on coal or running off 100% coal. All I'm saying is its been a choice to demolish our remaining working coal power stations. Will that be a good choice time will tell. I don't think it is. A lot here seem to be doing some impressive mental gymnastics to explain why China are building lots of new coal plants but it's ok for them. 

If any coal stations were currently operational it would be wise not to shut them down. As I mentioned RoS was extended because of high gas prices. 

 

But my point is, they are shut down so it's water under the bridge. 

 

Two points to note are that the % of our total generation that used to be coal 30-40% in the late 00's early 10's is now supplied by renewables. So we have, in a sense, already replaced them. 

 

Secondly, coal prices are not immune to the current situation, so electricity from coal would be subject to the same price linkage as gas and oil. 

 

As for China. 

 

They are in a different situation from thr UK, their power demands are still growing. They are having to add more generation. 

 

Ideally all of this and more would be from renewables. 

 

Instead it is mostly (in the 4/5 range) from renewables and crucially the renewable addition is greater than the growth, so the proportion of coal is falling. 

 

It's not perfect but it is pretty good. Again they install more wind capacity that the entire UK grid every quarter. It's mind boggling - it also gives lie to the claim that renewables are a Chinese plot to cripple western industry.... 

[SteamyTea]

43 minutes ago, Beelbeebub said:

Of course this is a win/win for the fossil fuel providers, not only do they get to keep selling their product, but demand actually goes up

And it has still not happened apart from some small scale tests plants. It has been around over 30 years.

[Beelbeebub]

43 minutes ago, -rick- said:

 

This and long term this is where hydrogen can be useful. Use excess solar during the summer to make hydrogen, store it for peaker use in winter. All done in one site, no need to pipe it anywhere.

 

Other note is that batteries can fill all the short term responsive capacity that peaker/stored hyrdo used to do. The only thing batteries can't really do is longer duration peaker load. ie, those 1-2week super cold winter periods.

The problem is and always will be storage of the amounts of H2 required. 

 

Just doing a quick calculation (may be wrong so here's the working) 

 

A large LNG carrier has around 250,000 m3 of LNG

 

1m3 of LNG is about 6.8Mwh thermal which equates to about 2.7Mwh electric (roughly 40% efficient). 

 

So a very large LNG carrier has 250,000 x 2.7Mwh = 680,000Mwh or 680Gwh of electricity. 

 

The UK uses around 22,000 Gwh in a cold month (and that's before we electrify heating and transport!). Which is about 700 Gwh a day. 

 

So we would need about 14 LNG tankers of storage for a fortnight. 

 

The problem is H2 is much harder to store cryogenically - it needs to be at - 250C or so. But if it was, it's energy density is 2.7mwh thermal per m3 so roughly 40% of LNG, that meany ou now need to store about 35 liquid H2 carriers holding H2 at -250C.

 

 

If we store it as a compressed gas, the figures are even worse. 

 

 

[-rick-]

2 minutes ago, Beelbeebub said:

The problem is and always will be storage of the amounts of H2 required. 

 

Yep. Agree. Though you are assuming these plants would provide 100% of energy during the cold periods. Far from it. It would be there to augment existing supply not sure by how much but it will be a big difference.

 

It would also be spread over many plants and the production side is relatively easier than LNG (as it's slow, not needing to compress at the speed that LNG plants do). But storage is a huge issue. For that reason I wonder if we do end up going down this sort of route we end up converting hydrogen to methane before liquifying it. Horrendously inefficient but also if done as a way to use summer excess (on massively overbuilt solar so that the deficit during winter is smaller) then might still make sense especially if it means existing natural gas users can switch to this supply too without retooling. To be clear its not a valid option for wide scale use but for some niche usecases where electric heating is not an option it might make sense.

 

We imported 25% of our gas via LNG in 2024, this contingency capacity would less than 25% of our existing gas usage.

[Beelbeebub]

36 minutes ago, -rick- said:

Yep. Agree. Though you are assuming these plants would provide 100% of energy during the cold periods. Far from it. It would be there to augment existing supply not sure by how much but it will be a big difference

Good point. 

[Beelbeebub]

38 minutes ago, -rick- said:

It would also be spread over many plants and the production side is relatively easier than LNG (as it's slow, not needing to compress at the speed that LNG plants do). But storage is a huge issue. For that reason I wonder if we do end up going down this sort of route we end up converting hydrogen to methane before liquifying it. Horrendously inefficient but also if done as a way to use summer excess (on massively overbuilt solar so that the deficit during winter is smaller) then might still make sense especially if it means existing natural gas users can switch to this supply too without retooling. To be clear its not a valid option for wide scale use but for some niche usecases where electric heating is not an option it might make sense.

If we are going down the speculative route I would propose Amonia production from spare electric.  

 

Relatively easy to store at normal pressures and temperatures. It is toxic so the stores would need careful positioning. 

 

It can be burned as a fuel for turbines but also converted to hydrogen for high temperature industrial and chemical uses. 

 

It is also an important precursor chemical for fertiliser production.... 

 

As you point out the synthesis may be inefficient, possibly more than just to H2 but if we are talking summer excess elec that we wouldn't be using anyway then the efficency is moot. 

 

This is the point of overbuilding our capacity. 

 

My solar array is way oversized. It punts out over 10kw on a sunny day. And after I have filled my 10kwh battery by mid morning I'm limited to 3.6kw export. 

 

But it does mean that even on a fairly overcast day like today I'm still generating over 1kw, which is plenty for my house and trickle charging my battery for overnight. 

 

If I could figure out a way of using the summer excess, even if it was inefficent it would be great.  If I could store that excess for winter use, even at 50% or less round trip efficency, I could probably never need the grid. 

[SteamyTea]

Can we get our kW, kWh, MWh and so forth correct.

It looks so much better.

I use the dictionary on my phone to make it easy.