The Alternative Green Energy Thread

JKenH

michaels said:

JKenH said:

Soaring gas prices boost 'green' hydrogen

Surging natural gas prices mean the cleanest form of hydrogen is now the cheapest to produce, new research has suggested, giving the green technology a major boost after years of being held back by cost. 

Making hydrogen by splitting water using electricity from renewable sources costs almost a fifth less in Britain than using power produced by natural gas, according to calculations from market intelligence group ICIS. 

https://www.telegraph.co.uk/business/2021/11/11/soaring-gas-prices-boost-green-hydrogen/

Interesting and positive if true - but doesn't electrolysis cost basically depend on the cost of electricity which, because it is the marginal energy source, is currently tied to the high price of gas?

True, but I have always argued that is also the case for charging electric cars. Those of us who use our Zappi chargers to fill up with free sunshine often argue that the electricity going into the car is CO2 free but it is marginal use and hence is usually gas (or even coal) fuelled. If we weren’t charging our car then that PV generation would offset use elsewhere on the grid.

If however you build a renewable energy plant specifically to generate H2 then all is good. The renewable electricity consumed is no longer marginal generation, it is primary use and wouldn’t otherwise go into the grid. 

You might argue the same if having already purchased an electric car you then went out and bought solar panels and a Zappi to charge it. Those of us, however, who already have solar panels and then buy a car to mop up excess generation that otherwise would go into the grid must accept that gas and coal has to be used to replace that electricity so our car is only as clean as the marginal generation source. 

QrizB

michaels said:

JKenH said:

Soaring gas prices boost 'green' hydrogen

Surging natural gas prices mean the cleanest form of hydrogen is now the cheapest to produce, new research has suggested, giving the green technology a major boost after years of being held back by cost. 

Making hydrogen by splitting water using electricity from renewable sources costs almost a fifth less in Britain than using power produced by natural gas, according to calculations from market intelligence group ICIS. 

https://www.telegraph.co.uk/business/2021/11/11/soaring-gas-prices-boost-green-hydrogen/

Interesting and positive if true - but doesn't electrolysis cost basically depend on the cost of electricity which, because it is the marginal energy source, is currently tied to the high price of gas?

According to the article, green hydrogen companies strike long-term deals with renewable generators so the spot price of electricity isn't a factor in the price of their product.

michaels

JKenH said:

michaels said:

JKenH said:

Soaring gas prices boost 'green' hydrogen

Surging natural gas prices mean the cleanest form of hydrogen is now the cheapest to produce, new research has suggested, giving the green technology a major boost after years of being held back by cost. 

Making hydrogen by splitting water using electricity from renewable sources costs almost a fifth less in Britain than using power produced by natural gas, according to calculations from market intelligence group ICIS. 

https://www.telegraph.co.uk/business/2021/11/11/soaring-gas-prices-boost-green-hydrogen/

Interesting and positive if true - but doesn't electrolysis cost basically depend on the cost of electricity which, because it is the marginal energy source, is currently tied to the high price of gas?

True, but I have always argued that is also the case for charging electric cars. Those of us who use our Zappi chargers to fill up with free sunshine often argue that the electricity going into the car is CO2 free but it is marginal use and hence is usually gas (or even coal) fuelled. If we weren’t charging our car then that PV generation would offset use elsewhere on the grid.

If however you build a renewable energy plant specifically to generate H2 then all is good. The renewable electricity consumed is no longer marginal generation, it is primary use and wouldn’t otherwise go into the grid. 

You might argue the same if having already purchased an electric car you then went out and bought solar panels and a Zappi to charge it. Those of us, however, who already have solar panels and then buy a car to mop up excess generation that otherwise would go into the grid must accept that gas and coal has to be used to replace that electricity so our car is only as clean as the marginal generation source. 

I think average generation CO2 is probably a fairer benchmark - otherwise where do you draw the line - what if I replace my gas hob with an induction stove?  If I use an electric kettle rather than an old fashioned one on a gas hob is that all marginal use?!

JKenH

By and large we use up all the renewably generated energy first so whatever additional load we put on the grid is going to be met by marginal generation. So in theory whenever we switch a light on or plug in a kettle it is supplied by marginal generation (gas/coal). In practice there is inertia in the grid so one kettle in the short term isn’t going to have any impact. There might be a microscopic variation in frequency or voltage but no one is going to be shovelling coal into a boiler or opening a gas valve.

If however we look at things on a macro scale, say we add 100,000 electric cars to the grid, then that is additional demand (c300GWh) and inevitably has to be supplied by marginal generation. 

Yes, one can argue that the load from the electric cars can be anticipated (not on an individual level but as an average) so might be considered baseload but the bottom line is that if we have a we have a finite renewable energy supply then if there is a mass change of habit (electric car adoption) then that must increase demand for marginal generation. We have therefore to generate an additional 300 GWh from gas or coal more than if we had stuck with our ICE cars. I am not saying we shouldn’t move to electric cars but we are deluding ourselves if we pretend that they aren’t fuelled by marginal generation, i.e. predominately gas and coal. 

Ah, some might say, but we are increasing RE generation to meet the extra demand from EVs. Until such time as marginal generation is provided by RE (and that is years away) any extra load we add to the grid will be met by gas and coal (or imports).

The reality, though, is that RE generation has stalled. If we look at the last 12 months and compare it with the same period one year earlier we generated just 72TWh of our electricity from wind and solar compared to 78 TWh a year earlier. 

https://electricinsights.co.uk/#/dashboard?period=1-year&start=2020-11-12&&_k=7ssoc5

ed110220

JKenH said:

By and large we use up all the renewably generated energy first so whatever additional load we put on the grid is going to be met by marginal generation. So in theory whenever we switch a light on or plug in a kettle it is supplied by marginal generation (gas/coal). In practice there is inertia in the grid so one kettle in the short term isn’t going to have any impact. There might be a microscopic variation in frequency or voltage but no one is going to be shovelling coal into a boiler or opening a gas valve.

If however we look at things on a macro scale, say we add 100,000 electric cars to the grid, then that is additional demand (c300GWh) and inevitably has to be supplied by marginal generation. 

Yes, one can argue that the load from the electric cars can be anticipated (not on an individual level but as an average) so might be considered baseload but the bottom line is that if we have a we have a finite renewable energy supply then if there is a mass change of habit (electric car adoption) then that must increase demand for marginal generation. We have therefore to generate an additional 300 GWh from gas or coal more than if we had stuck with our ICE cars. I am not saying we shouldn’t move to electric cars but we are deluding ourselves if we pretend that they aren’t fuelled by marginal generation, i.e. predominately gas and coal. 

Ah, some might say, but we are increasing RE generation to meet the extra demand from EVs. Until such time as marginal generation is provided by RE (and that is years away) any extra load we add to the grid will be met by gas and coal (or imports).

The reality, though, is that RE generation has stalled. If we look at the last 12 months and compare it with the same period one year earlier we generated just 72TWh of our electricity from wind and solar compared to 78 TWh a year earlier. 

https://electricinsights.co.uk/#/dashboard?period=1-year&start=2020-11-12&&_k=7ssoc5

That's a pretty bad abuse of marginal emissions theory. It's only appropriate to use it for instantaneous to short term changes where the load changes but the generation system is the same.

(Ab)using it for longer term changes leads to the benefits of adding low carbon electricity being assigned to old uses of electricity, leaving new uses to be thought of as consuming the dirty power. The logic of that would be, say radios being old tech running on nice clean electricity and smart phones being new running on coal power. Clearly that would be absurd, showing why marginal emissions theory is inappropriate for longer term technological changes.

Here's an interesting article that goes into more detail: When to use Marginal Emissions (and when not to) | A New Shade of Green | Sherry Listgarten | Palo Alto Online |

The year-on-year drop in renewable generation was due to exceptionally low wind speeds. According to the Times April-Sep 2021 was the least windy such period for most of the UK and Ireland in 60 years. Stay calm about the year’s unusual wind drought | Register | The Times

1.7 GW of wind has been added from Q2 2019 to Q2 2021 (see Energy Trends: UK renewables - GOV.UK (www.gov.uk)) and at least 4.8 GW of off-shore wind is under construction and expected in the next few years. If we take the average offshore UK capacity factor of 40% (this is a pessimistic assumption as newer farms having larger turbines tend to have higher factors) the 4.8 GW under construction will add 16,819 GWh per year. Taking 200 Wh/km as an average EV consumption and 12,000 km as average distance a UK driver drives per year, I make that enough electricity for about 7 million EVs. Clearly the assumption that EVs are going to be added to an electricity grid that is basically the same as today is wildly inaccurate.

michaels

Also EVs are probably the ultimate 'charge when grid usage is lowest' over night and thus greenest load so actually probably use greener energy than the average - and also thus shift demand making it more constant which will again support RE rollout.

Spies

How do the national grid deal with sources they can't 'see' like domestic solar installations? 

QrizB

Spies said:

How do the national grid deal with sources they can't 'see' like domestic solar installations? 

Small generators (like you and me) are simply seen as a reduction in demand. Unless the whole street gets solar, it's very unlikely that we will end up back-feeding any circuit beyond the local one.

ed110220

Spies said:

How do the national grid deal with sources they can't 'see' like domestic solar installations? 

Those are probably quite easy to estimate compared with the impacts of human behaviour on demand. They will know how much PV has been installed and then they can use weather forecasts/observations to estimate how much they will be/are generating. 

JKenH

ed110220 said:

JKenH said:

By and large we use up all the renewably generated energy first so whatever additional load we put on the grid is going to be met by marginal generation. So in theory whenever we switch a light on or plug in a kettle it is supplied by marginal generation (gas/coal). In practice there is inertia in the grid so one kettle in the short term isn’t going to have any impact. There might be a microscopic variation in frequency or voltage but no one is going to be shovelling coal into a boiler or opening a gas valve.

If however we look at things on a macro scale, say we add 100,000 electric cars to the grid, then that is additional demand (c300GWh) and inevitably has to be supplied by marginal generation. 

Yes, one can argue that the load from the electric cars can be anticipated (not on an individual level but as an average) so might be considered baseload but the bottom line is that if we have a we have a finite renewable energy supply then if there is a mass change of habit (electric car adoption) then that must increase demand for marginal generation. We have therefore to generate an additional 300 GWh from gas or coal more than if we had stuck with our ICE cars. I am not saying we shouldn’t move to electric cars but we are deluding ourselves if we pretend that they aren’t fuelled by marginal generation, i.e. predominately gas and coal. 

Ah, some might say, but we are increasing RE generation to meet the extra demand from EVs. Until such time as marginal generation is provided by RE (and that is years away) any extra load we add to the grid will be met by gas and coal (or imports).

The reality, though, is that RE generation has stalled. If we look at the last 12 months and compare it with the same period one year earlier we generated just 72TWh of our electricity from wind and solar compared to 78 TWh a year earlier. 

https://electricinsights.co.uk/#/dashboard?period=1-year&start=2020-11-12&&_k=7ssoc5

That's a pretty bad abuse of marginal emissions theory. It's only appropriate to use it for instantaneous to short term changes where the load changes but the generation system is the same.

(Ab)using it for longer term changes leads to the benefits of adding low carbon electricity being assigned to old uses of electricity, leaving new uses to be thought of as consuming the dirty power. The logic of that would be, say radios being old tech running on nice clean electricity and smart phones being new running on coal power. Clearly that would be absurd, showing why marginal emissions theory is inappropriate for longer term technological changes.

Here's an interesting article that goes into more detail: When to use Marginal Emissions (and when not to) | A New Shade of Green | Sherry Listgarten | Palo Alto Online |

The year-on-year drop in renewable generation was due to exceptionally low wind speeds. According to the Times April-Sep 2021 was the least windy such period for most of the UK and Ireland in 60 years. Stay calm about the year’s unusual wind drought | Register | The Times

1.7 GW of wind has been added from Q2 2019 to Q2 2021 (see Energy Trends: UK renewables - GOV.UK (www.gov.uk)) and at least 4.8 GW of off-shore wind is under construction and expected in the next few years. If we take the average offshore UK capacity factor of 40% (this is a pessimistic assumption as newer farms having larger turbines tend to have higher factors) the 4.8 GW under construction will add 16,819 GWh per year. Taking 200 Wh/km as an average EV consumption and 12,000 km as average distance a UK driver drives per year, I make that enough electricity for about 7 million EVs. Clearly the assumption that EVs are going to be added to an electricity grid that is basically the same as today is wildly inaccurate.

Long time no hear. Pleased that my post sparked your interest. It did not pass me by that you felt the need to use terms such as “abuse/abusing” and “wildly inaccurate” in your response. 

There is an interesting quote in the Sherry Listgarten article you linked.

“Unfortunately, there is some lack of agreement around which emissions model to use for which purposes, and Lena Perkins says that this can make the metrics vulnerable to “cherry picking”, when people use the metric that makes their initiative look most compelling.”

Yes, I chose a model which supported my point - it would be illogical to do otherwise. I am sure you choose the model that best suits your arguments. I acknowledge there are two points of view on the issue of marginal generation when it comes to EVs. We are unlikely to agree but not a problem, we just see things differently - the world won’t end. Some may follow my logic while others will reject it.

Whatever the reason, wind generation was down year on year (despite the increase in installed capacity you mention), as was solar, yet over the same period we added around 175,000 BEVs and 110,000 PHEVs. Just where did the additional generation come from to charge those cars?