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Prediction: Coal has fallen. Nuclear is next then Oil.

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I've read that 6 hour battery storage in a locale with wind+sun covers close to 100% of non-corner-case demand. If WS is 2¢ a kWh and battery is 10¢ a kWh** the weighted wholesale price is 4¢ a kWh.

Since that scenario is available today and will only improve in the future, I don't think battery storage should be pigeon holed as a curtailment solution. Not that I really understand what 'avoiding curtailment' means in this context, since one would plan for clean energy production in excess of immediate demand to use later. But maybe I'm just tilting at a semantic proposition without a practical difference. One thing for sure though, the notion that that we should overbuild cheap WS to partly cover the generation lows has never made sense to me as an isolated idea.


** 0.9 cycles a day for 12 years, $400 a kWh installed

If the batteries are being used 'appropriately' the marginal cost of energy should be 0 or < 0. If the RE you're using to charge the battery could have displaced ~11kWh of NG at the time it was used to charge the battery and all you're doing with the battery is displacing 10kWh of NG later.... what was the point? You just spent ~$200/kWh on a battery to reduce 10kWh of NG at one time instead of 11kWh at another time.

The energy you use to charge the battery NEEDS to be wind or solar that would have been wasted because supply exceeded demand. You need to take 10kWh of RE that would have displaced ~0kWh of NG because as much demand as RE would meet was already being met.

This is similar to the oversized array question. Do you invest in more panels or a bigger inverter? The answer changes as panels get cheaper in relation to the inverter. Does it make more sense to invest in batteries or more solar and wind. As renewables keep getting cheaper even faster than the cost of batteries generally the answer is more solar and wind... even if ~10% of your new solar and wind is 'thrown out' because there just isn't enough demand when it's produced.
 
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If the batteries are being used 'appropriately' the marginal cost of energy should be 0 or < 0. If the RE you're using to charge the battery could have displaced ~11kWh of NG at the time it was used to charge the battery and all you're doing with the battery is displacing 10kWh of NG later.... what was the point? You just spent ~$200/kWh on a battery to reduce 10kWh of NG at one time instead of 11kWh at another time.

The energy you use to charge the battery NEEDS to be wind or solar that would have been wasted because supply exceeded demand. You need to take 10kWh of RE that would have displaced ~0kWh of NG because as much demand as RE would meet was already being met.

This is similar to the oversized array question. Do you invest in more panels or a bigger inverter? The answer changes as panels get cheaper in relation to the inverter. Does it make more sense to invest in batteries or more solar and wind. As renewables keep getting cheaper even faster than the cost of batteries generally the answer is more solar and wind... even if ~10% of your new solar and wind is 'thrown out' because there just isn't enough demand when it's produced.

That's logical, but completely un-nuanced. You can't build enough excess solar to cover the gap during cloudy days and sporadic rain storms and the sporadic calm nights. In those situations, battery does indeed displace NG, since it's not a seasonal difference, but an intermittent one. There has to be some amount of batteries with solar/wind, otherwise, you'll be more reliant on NG.
 
The energy you use to charge the battery NEEDS to be wind or solar that would have been wasted because supply exceeded demand.

I think we agree although I don't frame the problem as you are doing.

You seem to say: we overbuilt, so lets take the free 'waste' and put it in a battery

I say: we can economically time shift some of the clean generation


In each case the result is the same: supply in excess of demand is stored for later use. The POV I am used to fits in well with the market economy: so long as time shifted clean generation is cheaper than on demand combustion, the latter will be displaced.
 
There has to be some amount of batteries with solar/wind, otherwise, you'll be more reliant on NG.

My point is that if done poorly it's very easy to INCREASE reliance on NG by adding batteries. Maybe not in terms of capacity but energy. Sure... maybe a large battery bank might allow the retirement of 1GW of gas capacity. But that's a meaningless victory if the capital invested in that battery could have been used to reduce overall NG used more with an investment in renewables. From an emissions perspective if the choice is between investing $1B in storage so you can retire a 1GW gas plant OR.... KEEP the gas plant, skip the battery and produce another ~4TWh/yr of wind. I vote keep the gas plant and use less gas with more wind. What's the point of displacing 10kWh of NG later with a battery if you can just displace ~11kWh now?

I couldn't care less how many GW of gas turbines we have... so long as we keep dropping the GWh/yr.
 
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My point is that if done poorly it's very easy to INCREASE reliance on NG by adding batteries. Maybe not in terms of capacity but energy. Sure... maybe a large battery bank might allow the retirement of 1GW of gas capacity. But that's a meaningless victory if the capital invested in that battery could have been used to reduce overall NG used more with an investment in renewables. From an emissions perspective if the choice is between investing $1B in storage so you can retire a 1GW gas plant OR.... KEEP the gas plant, skip the battery and produce another ~4TWh/yr of wind. I vote keep the gas plant and use less gas with more wind. What's the point of displacing 10kWh of NG later with a battery if you can just displace ~11kWh now?

I couldn't care less how many GW of gas turbines we have... so long as we keep dropping the GWh/yr.

But you've been proposing an either/or situation. That $1B in storage HAS TO BE spent to supplement the wind/solar that you've produced. You can't just add 4TWh/yr of wind without the ability to smooth out the intermittency of wind. Otherwise, all you've done is curtail more power without filling in the troughs. You're trying to solve seasonal energy demands and ignoring the daily/hourly needs.
 
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As renewables keep getting cheaper even faster than the cost of batteries generally the answer is more solar and wind... even if ~10% of your new solar and wind is 'thrown out' because there just isn't enough demand when it's produced.
This is spot on and touches on an interesting topic - the concept of "throwing away" solar/wind when they are overproducing is often worded like that's a bad thing.

In fact, it's not, as long as the remaining energy that is sold still allows for the solar/wind generators to make a bit of money.

Gas, coal and oil burning power plants are "throwing away" capacity all the time. Yet it's not an issue until the overhead of running the plant overwhelms the value of the energy produced. There are gas peaker plants that are kept around just to run them for a dozen hours a year.

Mid-day energy will get very cheap in the spring and fall thanks to abundant and cheap solar PV energy. This is a good thing. With the proper retail pricing signals, consumers will shift demand to take advantage of it to some degree.

We should be encouraging people to charge their EVs from 9-4 PM - in California when the grid is the cleanest and solar/wind is most likely to be curtailed. But instead most utilities incentivize charging from 12 - 6 AM - when emissions are fairly high.
 
I think the TOU algorithms get really fuzzy and challenging. The TOU probably should be changed but also be done monthly. 9-4 pm may be great in spring and fall but not winter and summer (I don't know this for sure of course).
The time is now to start educating the population with variable TOU. Sure it is challenging but computers can do the hard work. Such an easy thing to do to save so much money in storage. All batteries should be put in cars and then the cars should charge when best for the grid. Might be nighttime in some seasons and daytime in others. With 300 mile cars and 25 mile average daily use, there is a lot of swing....
 
At least V1G, better V2G.

BTW, unless you are producing solar power inside the city, you still have grid limit to worry about during the day. See CAISO chart.

1620828984509.png
 
If the batteries are being used 'appropriately' the marginal cost of energy should be 0 or < 0. If the RE you're using to charge the battery could have displaced ~11kWh of NG at the time it was used to charge the battery and all you're doing with the battery is displacing 10kWh of NG later.... what was the point? You just spent ~$200/kWh on a battery to reduce 10kWh of NG at one time instead of 11kWh at another time.

The energy you use to charge the battery NEEDS to be wind or solar that would have been wasted because supply exceeded demand. You need to take 10kWh of RE that would have displaced ~0kWh of NG because as much demand as RE would meet was already being met.

This is similar to the oversized array question. Do you invest in more panels or a bigger inverter? The answer changes as panels get cheaper in relation to the inverter. Does it make more sense to invest in batteries or more solar and wind. As renewables keep getting cheaper even faster than the cost of batteries generally the answer is more solar and wind... even if ~10% of your new solar and wind is 'thrown out' because there just isn't enough demand when it's produced.
Solar farm operators don't care about how much NG is displaced, they care about how much they earn displacing it.

Solar farms are already oversized, and the oversize is _increasing_.
Solar farms also have production curves that mean that most of the time there's a large amount of spare transmission and inverter capacity.
 
My point is that if done poorly it's very easy to INCREASE reliance on NG by adding batteries.

I don't see that happening, except during transitions where tariff rules lag the market where WS is cheaper than NG. Delivered NG to the utility would have to cost under 1¢ a kWh (30¢ a therm) for that scenario to have any chance of existing in a rational market.

Biden is going to set a social cost of carbon to somewhere in the range of $50 - $70 a ton with escalation (5 - 7 ¢ a kWh). NG cannot hope to compete.
 
I don't see that happening, except during transitions where tariff rules lag the market where WS is cheaper than NG. Delivered NG to the utility would have to cost under 1¢ a kWh (30¢ a therm) for that scenario to have any chance of existing in a rational market
"rational" ^

Here in Ontario, a "global adjustment" charge is levied to make it financially prudent for gas (I hate the term "natural") plants to survive even in the face of fuel prices.

Hourly Ontario Energy Price at 12:00 p.m. EST May 12 2021
$11.53 / MWh
Global Adjustment 1st Estimate (May)
$98.51/ MWh

^ The majority of power cost is due to this adjustment. Wholesale electricity prices are nearly free at this time, effectively, if you want to sell electricity on to the Ontario grid right now, you'd get 1c/kWh. No surprise, gas generation is 115MW out of 9000MW capacity, it doesn't pay so they don't play, but they get paid regardless for backup capacity out of the adjustment charge.

The best way to "compete" or have a "rational" market is for individual home owners or businesses to put up renewables behind the meter. That is happening,

Ontario has 2GW of solar behind the meter, and only 500MW connected into the distribution/transmission system. In Ontario, there is no incentive for new solar or wind to be connected to the distribution/transmission grid, but there is significant incentive behind the meter as power costs are 12c/kWh at the low and 20c/kWh near peak, making it possible for 7 year payback on a modest 4kW solar system like I have.
 
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It would have to because of physics. The round trip efficiency of a battery isn't 100%. It's ~90%. So if you're not using curtailed RE you can either displace 10kWh of NG now or use a battery to displace 9kWh later.

Energy storage is considered a green technology. But it actually increases carbon emissions.


Dave Roberts is awesome -- everybody interested in the clean energy economy should support him and read his letters.

I have no problem with his analysis and arguments except to say that arbitrage is the engine that is putting dirty energy into storage, and that arbitrage will be transient for two reasons: clean energy output will grow and become a bigger player on the wholesale markets; and most importantly, market distorting contracts will expire.

It is certainly true that storage is energy source agnostic in a market economy that externalizes pollution costs, but even that fossil fuel tilted playing field will fall to clean energy that is cheaper than fossils despite the political advantage.

storage from clean-energy is cheaper than storage from fossils. That arbitrage will prevail.
 
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It would have to because of physics. The round trip efficiency of a battery isn't 100%. It's ~90%. So if you're not using curtailed RE you can either displace 10kWh of NG now or use a battery to displace 9kWh later.

Energy storage is considered a green technology. But it actually increases carbon emissions.

Only for coal vs Ng.

Say a battery bank absorbs cheap energy being produced by coal plants overnight and then discharges it in the day, competing with natural gas combined-cycle (NGCC) plants. The net effect will be to favor coal against natural gas, thus increasing net emissions
 
I thought this was interesting, from South Australia (formerly known as the land of expensive electricity):

TOU plans offered to consumers. 1 AUD = 0.78 USD

  • Off-Peak = 10am – 3pm
  • Shoulder = 1am – 6am
  • Peak = 6am – 10am and 3pm – 1am
Notice how off-peak is a fair description of most of the PV curve ? That is not by accident. Wholesale off-peak futures price is 3.8 AU ¢ per kWh.
SA today is the near future of California where TOU hours are concerned.
 
....

Mid-day energy will get very cheap in the spring and fall thanks to abundant and cheap solar PV energy. This is a good thing. With the proper retail pricing signals, consumers will shift demand to take advantage of it to some degree.

We should be encouraging people to charge their EVs from 9-4 PM - in California when the grid is the cleanest and solar/wind is most likely to be curtailed. But instead most utilities incentivize charging from 12 - 6 AM - when emissions are fairly high.

Yes, in sunny climates, need to charge EVs in day when sun is shining. Most workplaces should have EV chargers in parking lots.
 
I thought this was interesting, from South Australia (formerly known as the land of expensive electricity):

TOU plans offered to consumers. 1 AUD = 0.78 USD

  • Off-Peak = 10am – 3pm
  • Shoulder = 1am – 6am
  • Peak = 6am – 10am and 3pm – 1am
Notice how off-peak is a fair description of most of the PV curve ? That is not by accident. Wholesale off-peak futures price is 3.8 AU ¢ per kWh.
SA today is the near future of California where TOU hours are concerned.

Happening in San Diego in the Spring. Yes, having more solar would be awesome and perhaps make 10-3 super off peak year round.
 
It would have to because of physics. The round trip efficiency of a battery isn't 100%. It's ~90%. So if you're not using curtailed RE you can either displace 10kWh of NG now or use a battery to displace 9kWh later.

Energy storage is considered a green technology. But it actually increases carbon emissions.

That article, written in 2018, may still be true today somewhat, but given the scale of grid-scale storage and renewables then, it's not surprising.

But today, with ever-increasing amounts of solar/wind being curtailed, it's pretty clear that batteries are starting to do real load shifting of renewables that is reducing overall emissions.

Here's the grid profile of utility scale batteries from yesterday - see how they were generally charging during sunny hours, and discharging during the morning and evening peak - when gas peaker plants are running.

2021-05-13_00-50.png