Gas or electric?

[wilco88]

Nothing like a healthy debate!

 

[IT Minion]

Assumptions, always dangerous things.


You said FF not CO2 producers, so I excluded biomass, that is >6% ATM and I think pretty constant as the plant was not designed to vary rapidly.

...Despite this intent for baseload operation, it was designed with a reasonable ability for load-following, being able to ramp up or down by 5% of full power per minute within the range of 50–100% of full power.[9]

https://en.m.wikipedia.org/wiki/Drax_Power_Station

Yeah, damn those assumptions.

 

[Harry Bloomfield]

If more electric heating is used then I would expect the amount of gas used to increase as it is common for huge swathes of the unreliables to stop at the same time so it does not matter how many are installed.

and at a guess, I would suggest electric produced by gas, due to distribution network losses, is much less efficient than simply burning it at home. That is apart from the distribution network being massivley over subscribed, try support both heating and electric car loads, which it was never designed to do.

 

[mikeey84]

and at a guess, I would suggest electric produced by gas, due to distribution network losses, is much less efficient than simply burning it at home. That is apart from the distribution network being massivley over subscribed, try support both heating and electric car loads, which it was never designed to do.

It does appear, certainly in 2015, that electric generation from powerstations created more CO2 than an efficient gas boiler at home per KWh. But the balance in the grid has changed a lot in the intervening 5 years, with more and more wind power, so it may now not be true.

 

[StephenOak]

Despite this intent for baseload operation, it was designed with a reasonable ability for load-following, being able to ramp up or down by 5% of full power per minute within the range of 50–100% of full power.

Thanks for that. It wasn't just an assumption, "intent for baseload operation" was the norm for stations of this type when it was built. If I have time I will look at the figures for biomass later on.

Also, Drax creates a lot more CO2 than is recorded against it. The trees are harvested using diesel powered kit, the wood is chipped & dried by diesel or (substantially coal powered) electricity and the chippings are transported on ships powered by diesel or bunker fuel.

I would suggest electric produced by gas, due to distribution network losses, is much less efficient than simply burning it at home.

But the balance in the grid has changed a lot in the intervening 5 years, with more and more wind power, so it may now not be true.

And if you want to make wind a really significant part of the supply you need to introduce storage, which introduces transmission losses times two and losses in the storage mechanism.

 

[mikeey84]

And if you want to make wind a really significant part of the supply

I thought wind was already a significant part of the supply?

21% of 2019s electricity, 2nd only to gas

 

[StephenOak]

I thought wind was already a significant part of the supply?

21% of 2019s electricity, 2nd only to gas

Well, 21% is c. half of what gas supplies, so partly it depends on how you define 'significant' and 'really significant'!

Wind is essentially a 'nice to have' as it is not reliable. There are plenty of days when wind supplies essentially nothing, but gas & nuclear are supplying every day of the year. If all the wind went offline things would be tight but workable, if all the gas or nuclear went offline things would be disastrous.

 

[mikeey84]

Well, 21% is c. half of what gas supplies, so partly it depends on how you define 'significant' and 'really significant'!

Wind is essentially a 'nice to have' as it is not reliable. There are plenty of days when wind supplies essentially nothing, but gas & nuclear are supplying every day of the year. If all the wind went offline things would be tight but workable, if all the gas or nuclear went offline things would be disastrous.

True, don't want to argue about semantics!

We will never be able to manage with just wind, that is clear, and if we just wanted to replace all gas with wind, we would probably need 5x as much capacity as we have now, with a huge storage capacity, which ain't gonna happen over night, if at all

 

[IT Minion]

True, don't want to argue about semantics!

We will never be able to manage with just wind, that is clear, and if we just wanted to replace all gas with wind, we would probably need 5x as much capacity as we have now, with a huge storage capacity, which ain't gonna happen over night, if at all

It won't, but that's what things like biomass and short term storage are good for. Pumped hydro, batteries for daily variations and using things like Drax to provide seasonal power or to cover gaps in wind supply will sort most of it. Add in liquid air batteries, interconnects and flow batteries and the amount of Gas we need to backstop wind and solar will keep dropping until suddenly it'll be none.

 

[Harry Bloomfield]

It does appear, certainly in 2015, that electric generation from powerstations created more CO2 than an efficient gas boiler at home per KWh. But the balance in the grid has changed a lot in the intervening 5 years, with more and more wind power, so it may now not be true.

I was only referring to just section of the power produced by gas alone, rather than including the whole range of generation methods. Gas consumed for the generation of electrical power, used just for heating, cannot possibly come close to gas burned in a modern boiler for heating, where the heat produced is used close to the boiler.

 

[mikeey84]

was only referring to just section of the power produced by gas alone

Sorry if i wasn't clear, but that is what I was referring too.

Obviously the figure is vastly different for coal/nuclear/wind etc

 

[Harry Bloomfield]

Sorry if i wasn't clear, but that is what I was referring too.

Obviously the figure is vastly different for coal/nuclear/wind etc

Ignoring the losses at the point of generation, there are all of the losses in transformers and the network which I suspect are quite substantial. Gas delivered to a premises has much lower transmission losses, just minor leakages. Once it arrives at a boiler, gas boilers are 80 to 90% efficient.

End to end (generation, transformers, distribution networks and sub-stations) I have seen figures as high as 60% loss, to as low as 30% loss.

So taking the worst case example, they burn 1000w worth of gas and only deliver to the consumer 400w.

 

[mikeey84]

Ignoring the losses at the point of generation, there are all of the losses in transformers and the network which I suspect are quite substantial. Gas delivered to a premises has much lower transmission losses, just minor leakages. Once it arrives at a boiler, gas boilers are 80 to 90% efficient.

I'm not sure exactly where the measurement is taken, but the figures I saw compared co2 per kwh of gas power stations vs home gas boilers.

I'm not sure if the gas powerstation figure referred to kwh of electricity in a consumers home, or if it were "ex works figures" so to speak. Obviously that would make a significant difference for the reasons you outline, even given the fact that electrical heating is within a rounding error of 100% efficient

 

[IT Minion]

Ignoring the losses at the point of generation, there are all of the losses in transformers and the network which I suspect are quite substantial.

End to end (generation, transformers, distribution networks and sub-stations) I have seen figures as high as 60% loss, to as low as 30% loss.

I've seen numbers of less than 10%.

Transmission Losses vs Distribution Losses
On the Transmission network, the percentage of network losses is lower than on the distribution
network. Citizens Advice suggests that about 1.7% of the electricity transferred over the transmission
network is lost, and a further 5-8% is lost over the distribution networks2
.
This is because transporting electricity via a lower current and high voltage causes lower network
losses. The transmission network operates at ultra-high voltages to transfer bulk energy across long
distances –which minimises losses. However, higher voltages require better electrical insulation which
makes the cost of building and maintaining the transmission network more expensive.

If you're including thermal efficiency (ie. the amount of electricity harvested from thermal energy) then that's quite different from the transmission aspect.

How much energy does pumping all that gas around the system take?

 

[Harry Bloomfield]

I'm not sure exactly where the measurement is taken, but the figures I saw compared co2 per kwh of gas power stations vs home gas boilers.

But ignoring the massive losses between producer and consumer? Gas burned at a power station, for heating in the home, can only produce lower CO2 if the gas is only used when the wind doesn't blow the wind generators around AND if there are enough wind generation sources to supply all of our needs - home heating, lighting, the major load of charging electric vehicles and industry. When the wind doesn't blow, the CO2 generated is doubled by the burning of gas, assuming gas is the only other source.

I'm not sure if the gas powerstation figure referred to kwh of electricity in a consumers home, or if it were "ex works figures" so to speak. Obviously that would make a significant difference for the reasons you outline, even given the fact that electrical heating is within a rounding error of 100% efficient

Electrical heating is 100% efficient, once it gets into your home there are no possibly losses - you get every single Kw of electric converted to heat. There will be some tiny losses in your cables, due to resistance and self heating, but none of it is wasted - all of it adds to useful heat.