Another good reminder Declan that average emission intensity factors over egg storage scope 2s. Which begs another question - should lower fcas contribute towards scope 2 calcs, even though its providing a service? Not all scope 2s are the same it seems.
Yeah, goes to show that a one-sized fits all approach isn't good enough. Especially for storage. I think a more sensible approach would be having storage look at the differences between average grid emissions intensity in the dispatch intervals where it's importing vs. exporting. Should show storage taking mostly renewable energy and offloading it into peaks. And should cover off the lower FCAS stuff too!
Excellent post. I wonder if a simplified option can be provided to readers, that generally if they charge during daylight hours from around 9am to 3pm, then they are basically renewable. Maybe not today, or in all grids, but looking forward 50 or 100 years, it is true. It would round out some great analysis with an action or takeaway for readers who own EVs
Nice article, with a good explanation of marginal generators and emissions. The grid is already seeing periods of curtailment of utility and rooftop solar. This will dedinitely increase as the % RE increases, and so the % of time where RE is the marginal generator is going to increase. Also flexible charging where the charger responds to market price signals will also help reduce marginal emissions, as a high price is a clear indicator of when gas is the marginal generator.
Agree that we'll see more renewable curtailment, but the extent to which that changes the marginal generator is a little hazy. For utility scale solar, it might be curtailed by the market operator - if that happens, it would likely have capped output and would not be responding to small changes in electricity demand. Instead, this is covered by dispatchable generators who are providing FCAS or who otherwise respond to small changes in grid frequency. The small changes in load do not necessarily alleviate the constraint although it may lead to an increase in the utility scale solar dispatch target in the next interval. The other reason you'll get renewable curtailment is economic i.e., not running during negative pricing. I tried tackling this more in the article - I hope with more electrification, smart charging and load control, the cure to low prices becomes low prices!
Rooftop solar is different again. Most likely, rooftop solar curtailment has come about because there's something going on on the grid, or because the local network has capped the output. In both instances, this curtailment could be reduced by filling up EV.
On the last point, what you said is what's intuitive (and I had thought the same), but in the short term it's also not strictly right. Often the marginal generator in cheap times is coal, and expensive times is hydro or gas. If you only look at marginal emissions, you could conclude that charging in cheap periods runs more coal, compared to charging in expensive periods, which runs more gas/hydro. However, this is missing the longer term point that charging in cheap periods on masse is better utilising our existing renewables and supporting investments in new ones!
Another excellent example of people way smarter than me say things I try to say and it making far more sense. Thanks Dekkers
Thanks mate!
Another good reminder Declan that average emission intensity factors over egg storage scope 2s. Which begs another question - should lower fcas contribute towards scope 2 calcs, even though its providing a service? Not all scope 2s are the same it seems.
Yeah, goes to show that a one-sized fits all approach isn't good enough. Especially for storage. I think a more sensible approach would be having storage look at the differences between average grid emissions intensity in the dispatch intervals where it's importing vs. exporting. Should show storage taking mostly renewable energy and offloading it into peaks. And should cover off the lower FCAS stuff too!
Excellent post. I wonder if a simplified option can be provided to readers, that generally if they charge during daylight hours from around 9am to 3pm, then they are basically renewable. Maybe not today, or in all grids, but looking forward 50 or 100 years, it is true. It would round out some great analysis with an action or takeaway for readers who own EVs
Good points Jonathan! I did try to sum it up at the end, but I had to really break it down, people should (if they can):
1. Replace an ICE with an EV
2. Charge it from rooftop PV
3. If charging from the grid, charge during daylight hours.
4. Think about getting a smart charger than adapts charging to the grid.
If EV drivers can do this, it'll be great for the transition!
Nice article, with a good explanation of marginal generators and emissions. The grid is already seeing periods of curtailment of utility and rooftop solar. This will dedinitely increase as the % RE increases, and so the % of time where RE is the marginal generator is going to increase. Also flexible charging where the charger responds to market price signals will also help reduce marginal emissions, as a high price is a clear indicator of when gas is the marginal generator.
Thanks Andrew - a bit to unpack there.
Agree that we'll see more renewable curtailment, but the extent to which that changes the marginal generator is a little hazy. For utility scale solar, it might be curtailed by the market operator - if that happens, it would likely have capped output and would not be responding to small changes in electricity demand. Instead, this is covered by dispatchable generators who are providing FCAS or who otherwise respond to small changes in grid frequency. The small changes in load do not necessarily alleviate the constraint although it may lead to an increase in the utility scale solar dispatch target in the next interval. The other reason you'll get renewable curtailment is economic i.e., not running during negative pricing. I tried tackling this more in the article - I hope with more electrification, smart charging and load control, the cure to low prices becomes low prices!
Rooftop solar is different again. Most likely, rooftop solar curtailment has come about because there's something going on on the grid, or because the local network has capped the output. In both instances, this curtailment could be reduced by filling up EV.
On the last point, what you said is what's intuitive (and I had thought the same), but in the short term it's also not strictly right. Often the marginal generator in cheap times is coal, and expensive times is hydro or gas. If you only look at marginal emissions, you could conclude that charging in cheap periods runs more coal, compared to charging in expensive periods, which runs more gas/hydro. However, this is missing the longer term point that charging in cheap periods on masse is better utilising our existing renewables and supporting investments in new ones!