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Managing the Duck Curve and all of Its Foul Relatives

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John Benson's picture
Senior Consultant Microgrid Labs

PROFESSIONAL EXPERIENCE: Microgrid Labs, Inc. Advisor: 2014 to Present Developed product plans, conceptual and preliminary designs for projects, performed industry surveys and developed...

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  • Jun 29, 2021
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Electric utilities have been fighting the mismatch between when power generation is available and when the loads need the resulting electricity since Edison, Tesla and Westinghouse invented the modern electric utility industry.

The “Duck Curve” is a somewhat new species for this issue, but I’m sure we will be seeing more of its flock-mates as the grid-supply evolves.

This paper will address mismatches between electric supply and demand. I will do this for my home-state (California) and others can do the same for their home state.

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Bob Meinetz's picture
Bob Meinetz on Jun 29, 2021

"At this point in time, most of the combustion-turbine “peakers” have been retired, or should be shortly, so I will skip these."

John, what's your source for this statement? AFAIK, peakers in California are doing just fine, thanks to the threat irregular wind and solar generation pose to grid stability:

"Across California, nearly 80 gas-fired power plants help meet statewide peak electric demand. These plants include 65 combustion turbines designed to ramp quickly to meet peak demand, and over ten aging steam and combined cycle turbines now used infrequently to meet peak needs."

Re:

"There are a large number of combined cycle plants still operating, and they have a path to very low GHG (via biomethane..."

I think you'll find the exaggerated potential for biomethane is a construct of California's extracted gas industry, in which our current and former governor are significant stakeholders: 

"RNG is not as low-carbon as the industry claims and its local air and water impacts are concentrated in vulnerable communities. Even if it were low-carbon and equitable, there simply isn’t enough of it to substitute for more than a small fraction of natural gas. And even if it were low-carbon, equitable, and abundant, it still wouldn’t be an excuse to expand natural gas infrastructure or slow electrification.

It isn’t a close call. The research is clear: Especially in a temperate climate like California, RNG is not a viable alternative for decarbonizing buildings. It is a desperate bid by natural gas utilities to delay their inevitable decline. Policymakers would be foolish to fall for it."

Re: diversity requiring consideration of:

"The cost per kWh to build and operate a generation project while making a reasonable profit..."

Part of the problem. By "decoupling" electricity rates from utility profits (CA utilities make no profit on the electricity they sell), California's PUC has made building generation projects (and tearing them down) more profitable than operating them.

They do make a profit on the natural gas fuel that powers them, however, creating an incentive to burn as much gas as possible to generate each kWh of electricity. If you ask them what's a "reasonable" amount, they might say, "The sky's the limit!". Small wonder there are 65 California combustion turbines still in service.

Michael Keller's picture
Michael Keller on Jul 1, 2021

I agree with Bob. Using  bio derived fuel in a gas turbine is a very unlikely path. The machines can technically fire the fuel, but supplying the fuel is one hell of a problem.

Also, when you run the financials on an even handed basis, advanced gas turbines such as the LMS 100 are competitive with solar energy, while obviously being significantly more reliable and able to provide energy when needed.

Attempting to solve Duck Curve issues in California strikes me as fundamentally based on quackery. Making the wildly impractical assumption of zero CO2 emissions yields to not particularly rational solutions. As theses are the same folks hell-bent on shutting down the Diablo Canyon nuclear station, not surprising that La-La land type solutions emerge.

Matt Chester's picture
Matt Chester on Jun 29, 2021

Thanks for the great overview, John. I'm curious what role you think public policy / market regulation and the like can and should play. Is this an issue where stakeholders acting mostly in their own self-interest is causing the problems to worsen but a stronger central guiding authority can be justified for the benefit of the ratepayers, customers relying on the grid, etc. ?

John Benson's picture
John Benson on Jun 30, 2021

Hi Bob & Matt, Thanks for the Comments & Questions.

First Bob. I think I mostly agree with you, but with an explanation.

It would be an oversimplification to say combined cycle plants are mostly a combustion-turbine combines with a steam turbine bottoming unit (many optimizations of all subsystems to make the plant operate at a maximum efficiency when operating in a combined cycle mode), but one of the big advantages of the CC plants is that they can be operated in a combustion-turbine mode, where their optimizations are for fast-start and fast-ramp. CC Plants are the primary reason that simple peakers are going away. The other is that a battery energy storage system can replace them with no pollution (greenhouse gas or otherwise).

Also, since I've actually worked on one of these projects (Northern California Power Agency's Lodi Energy Center, which is a Siemens 296 Megawatt (MW) “Flex Plant 30″) I know that they are the most efficient units around, But they also (currently) emit greenhouse gas in large volumes. 

Like you, I believe that RNG (biomethane) is a spot solution currently, and is not carbon-neutral currently. It will take decades of development to get close to this. That is why I'm pushing carbon capture and sequestration concurrently with CC plants burning RNG. It will push us closer to carbon neutrality and maybe even negativity for the whole process.

Nothing is simple. We are trying to move from burning what ever we could get our hands on to making sure we will not emit any GHG (at all) for a full process, over a full lifetime - a major challenge. The reason I support using CC plants is that the GHG for building them is already in the atmosphere. Thus if we can modify them for carbon neutrality at a reasonable cost, then continue to operate them at a reasonable cost, they can make a powerful contribution to an overall solution, at least for a while.

Below is a description of a paper I posted in 2019. Near the end is a map showing all of the CC plants in California at that time. I count 22.

Zero-Emissions Combined Cycle and Beyond: This paper has a proposal that will keep combined cycle power plants running by converting them to (nearly) zero greenhouse gas (GHG) emission operation. Ultimately these can be converted to negative emissions technology to offset other GHG sources.

https://www.energycentral.com/c/cp/zero-emissions-combined-cycle-and-beyond

Now to Matt's question:

I've worked with the CPUC, CEC and all of the major utilities in California for over 40 years. In the last 20 of those years, they have all been really focused on mitigating climate change. I cannot believe they would knowingly make a decision that ran counter to that effort. Screw-ups, you betcha. Concerted decision, never. They are doing their best to drive us toward net-zero GHG.

-John

Joe Deely's picture
Joe Deely on Jul 1, 2021

John,

Here is some data that backs up your comments. EIA started breaking down NG generation by plant type in 2008. Generation from simple-cycle plants has declined from 36TWh in 2008 to 16 TWh in 2019.  Since these plants use a lot more NG per TWh eliminating simple-cycle NG generation should be a priority if we want to lower CO2 more efficiently.

Also, current "run-rate" for batteries on CAISO is about 3,000 MWh/day or 1TWh/year. This should double by the end of year. This implies that a further 8x increase in battery storage could eliminate the remaining 16 TWh of simple cycle generation.  Obviously it won't be a 1-1 drop but this is a good ballpark.

By the way thanks to Bob for this source - great info on replacing NG peakers in CA - highly recommended.

In this analysis, we assess where solar and storage have the potential to replace existing California peaker power plants and where their deployment may yield the greatest environmental health and equity benefits.  Across California, nearly 80 gas-fired power plants help meet statewide peak electric demand. These plants include 65 combustion turbines designed to ramp quickly to meet peak demand, and over ten aging steam and combined cycle turbines now used infrequently to meet peak needs.

Michael Keller's picture
Michael Keller on Jul 1, 2021

Zero emissions in California (or US for that matter) is not a logically sound position, particularly when viewed in the larger context of global CO2 emissions. Then throw in the fact that the threat of CO2 emissions is long range conjecture. The economics of zero emissions become irrational.

A simple follow-the-money analysis quickly leads to the conclusion that zero-emissions is largely a ploy to line the pockets of the well-off at the expense of most of the rest of the population.

Electricity generation should first and foremost be based on providing reasonably priced energy, and that goal also includes the profit motive. Technology innovations   to meet that goal inevitably lead to lower emissions. History provides ample demonstration of the validity of that approach. The evolution of gas turbines provides a text book example of how technology innovations lower production costs and emissions. As long as not used to the extreme, green energy can track along that same path.

Joe Deely's picture
Joe Deely on Jul 1, 2021

Zero emissions in California (or US for that matter) is not a logically sound position, particularly when viewed in the larger context of global CO2 emissions. Then throw in the fact that the threat of CO2 emissions is long range conjecture. The economics of zero emissions become irrational.

I wonder if the folks in Lytton B.C would agree with this point of view. Lytton set a new Canadian record the other day.

The village this week recorded the country's highest ever temperature of 49.6C (121.3F).

Then the town burned to the ground.

Out-of-control wildfires fed by a historic heatwave that then created rainless thunderstorms have converged on the small Canadian village of Lytton, engulfing the entire town in flames and destroying 90 percent of it, including the city center.

I wonder what the residents of Lytton think about the irrationality of the economics of zero emissions.

 

It's time to see and call out the Koch coal, oil and gas mafia for what they are - polluters and killers.

 

Michael Keller's picture
Michael Keller on Jul 3, 2021

Kindly provide the link between heat waves caused by jet stream oscillations and eddies over British Columbia and atmospheric CO2 concentrations. I”ll save you the effort. There isn’t any linkage.

You appear to be significantly challenged by reality, preferring instead to  believe emotionally driven hysteria emanating from environmental religious zealots.

John Benson's picture
John Benson on Jul 6, 2021

A post from about two years ago describes this in detail. This is described and linked below.

Climate change is caused by greenhouse gases (GHG), primarily carbon dioxide (CO2) and methane, increasing in the atmosphere. This results in atmospheric warming. There are also many secondary, tertiary and higher order effects, including the following:

• The sea-level rise

• Both heat and CO2 enter the oceans and the latter acidifies them.

• Disruption of the Meridional Overturning Circulation (MOC, the Gulf Stream and other major ocean currents).

• Increasing atmospheric temperatures and the MOC disruption have caused major changes to weather patterns around the world.

This paper is about an emerging understanding of the last bullet, and the impacts (so far), especially in North America.

https://www.energycentral.com/c/ec/emerging-negative-effects-climate-change

By the way, the slowdown of the Atmospheric Rossby waves described by this paper, and the attendant higher-order effects appear to be becoming more extreme every year (based on my casual observations).

-John

Michael Keller's picture
Michael Keller on Jul 7, 2021

There is no linkage that can be made. The chaotic non-linear nature of the planet’s climate precludes drawing any conclusions regarding weather extremes. The underlying mathematics cannot support any such conclusion.  Google Climate Etc. blog by   judithcurry.com
Pointing to studies with predetermined outcomes that rely on inappropriate use of statistics and modeling does not constitute proof. At best, inferences are being made.

Bob Meinetz's picture
Bob Meinetz on Jul 1, 2021

"...a battery energy storage system can replace them with no pollution (greenhouse gas or otherwise)."

There is no battery system in the world that can replace peaker plants, and there never will be (or should be). For many reasons:

1) Exorbitant expense. According to EIA:

"California had the most installed battery capacity of any state in 2019. The average battery storage cost in California was $1,522/kWh. About two-thirds of battery storage capacity in California is used for frequency regulation."

Do the math: to shave a tiny slice - 15 gigawatthours - from California's peak consumption each day, we'd need 15 million kWhs of battery capacity at a total cost of $1,522/kWh x 15,000,000 = $22.8 billion. They would need to be replaced every 7-10 years. They'd need 15 gigawatts of additional solar or wind to charge them (they can't charge themselves). They'd need to be charged with exclusively solar or wind energy (they aren't).

Batteries make new nuclear, even at inflated US prices, look like a bargain.

2) Despite popular misperceptions, battery energy storage systems are not "pollution-free". Why? They waste energy:

"...net system CO2 emissions resulting from storage operation are nontrivial when compared to the emissions from electricity generation, ranging from 104 to 407 kg/MWh of delivered energy depending on location, storage operation mode, and assumptions regarding carbon intensity."

3) Despite popular misperceptions, battery facilities are built next to solar and wind farms for appearance only. They charge from a grid mix, like they do anywhere else, but are placed there so naïve renewables advocates will think "the batteries are being charged by the sun by day, and are powering the grid at night!". And per above, they're adding 104 to 407 kg of CO2 to the emissions of that electricity, for every MWh they store.

"I've worked with the CPUC, CEC and all of the major utilities in California for over 40 years. In the last 20 of those years, they have all been really focused on mitigating climate change."

Perhaps you weren't of aware of the blatant corruption associated with the shutdown of San Onofre, or of the links between Jerry Brown / Gavin Newsom and California's natural gas industry. The commissioners of CPUC, CEC, and CARB are appointed by one man - the governor - and both of the above have consistently made energy-related decisions, and appointed commissioners, solely to enrich themselves at the expense of the environment.

"I cannot believe they would knowingly make a decision that ran counter to that effort [mitigating climate change]."

Believe it.

Finally, tell me why I should believe net-zero and carbon-neutral aren't little more than "I gave at the office" excuses for failing to reach zero fossil carbon emissions, as IPCC says we must, in eighty short years?

Joe Deely's picture
Joe Deely on Jul 1, 2021

There is no battery system in the world that can replace peaker plants, and there never will be (or should be). For many reasons:

1)Exorbitant expense. According to EIA:

"California had the most installed battery capacity of any state in 2019. The average battery storage cost in California was $1,522/kWh."

Do the math: to shave a tiny slice - 15 gigawatthours - from California's peak consumption each day, we'd need 15 million kWhs of battery capacity at a total cost of $1,522/kWh x 15,000,000 = $22.8 billion. They would need to be replaced every 7-10 years.

Don't know where you've been hiding, but California will easily have 15 gigawatthours of battery storage within a few years. In fact, could have 6-8 gigawatthours by the end of this year. 

They'd need 15 gigawatts of additional solar or wind to charge them (they can't charge themselves). 

No they don't?!  Many different ways to charge these - use a single hour from 15 GW = 15GWh and you still have 5-9 hours of solar for regular use, use 5 hours from 3 GW, etc..  

About two-thirds of battery storage capacity in California is used for frequency regulation.

No it's not. Again, time to wake up and see what is happening around you. Most of the battery capacity is now being used to time-shift generation - see chart below. Every new project added shifts more capacity into this mode.

Finally, this is just California. There are many other storage projects in the pipeline for NV, AZ, NM, etc... Plus there will be 40 GW of new renewable capacity added out West in the first half of his decade. The Western grid is getting cleaner every day.

 

Bob Meinetz's picture
Bob Meinetz on Jul 2, 2021

"California will easily have 15 gigawatthours of battery storage within a few years. In fact, could have 6-8 gigawatthours by the end of this year."

Source, please (home-made graphs / home-made data are unacceptable).

"Many different ways to charge these - use a single hour from 15 GW = 15GWh and you still have 5-9 hours of solar for regular use, use 5 hours from 3 GW, etc.."

Q: How many different ways are there to charge $23 billion worth of batteries on a cloudy day, or after 10 short years of operation? A: None, they're useless.

"Again, time to wake up and see what is happening around you."

What I see happening around me is marketers at the American Petroleum Institute hypnotizing innocent minds into believing solar and wind might one day end fossil fuel consumption - and they've been spectacularly successful (let us know when the blue line below trends downward, I won't be holding my breath).

It's time, Joe, to admit renewables are a scam.

Bob Meinetz's picture
Bob Meinetz on Jul 2, 2021

"'About two-thirds of battery storage capacity in California is used for frequency regulation.'

No it's not. Again, time to wake up and see what is happening around you."

Please follow the link I've provided to the website of the U.S. Energy Information Administration. Either: A) It's time for EIA analysts to wake up and see what's happening around them, or B) You're wrong. What are the chances?

"California had the most installed battery capacity of any state in 2019. The average battery storage cost in California was $1,522/kWh. About two-thirds of battery storage capacity in California is used for frequency regulation. Batteries in the state also provide energy-oriented services, including ancillary services, black start services, and easing transmission congestion."

Matt Chester's picture
Matt Chester on Jul 2, 2021

Can't batteries be used for frequency regulation on a regular basis and then for grid-level storage on an as-needed basis? I didn't think you had 'just frequency regulation batteries' in one corner and 'just energy storage batteries' in another-- or am I mistaken? 

Bob Meinetz's picture
Bob Meinetz on Jul 2, 2021

Matt, I think the author was using battery capacity as a generic term, unrelated to any specific facility. As in, "on average, 2/3 of California batteries are being used to regulate frequency."

But since they're charged from the grid, batteries can be used for whatever's profitable at the moment. They're often used to smooth the erratic output of wind and solar farms by ramping up at a moment's notice. The "just-in-time" energy demands of supply balancing, frequency regulation, voltage regulation, and easing transmission congestion come at a steep price, however, and they're problems for which renewables are entirely to blame.

In comparisons between the cost of renewable and nuclear energy, I have yet to see renewables advocates accept responsibility for any of these costs.
 

Michael Keller's picture
Michael Keller on Jul 7, 2021

If your underlying thesis is of doubtful validity, why pursue zero carbon policy?  Becomes even of more dubious value by looking at cost versus benefit. The costs are in the trillions of dollars and the benefit may or may not be show up in the distant future. Fails miserably on economics alone.

Michael Keller's picture
Michael Keller on Jul 7, 2021

San Onofre was shut down because Southern California Edison directed that the output of the steam generators be increased by adding more tubes. The original design of the steam generators was noticeably altered without the proper prototype testing and severe flow oscillations occurred causing unacceptable tube damage. That was not corruption, but it was dumb on the part of the utility to alter the original design.If they had simply followed the original design, the plant’s would be on line today.

The manufacture of the steam generators would have replaced the defective steam generators, but the utility would have pay the cost of the construction effort (tens of millions). The utility should have followed that path. Was not repairing San Onofre corruption? No, but it was another poor decision on the part of the utility.

Joe Deely's picture
Joe Deely on Jul 1, 2021

Saw this today... battery usage on CAISO hit a new high yesterday - 877 MW.  This would be close to using sixteen - 50 MW NG peakers.

Total discharge between 6-10pm was about 1,800 MWh.

Bob Meinetz's picture
Bob Meinetz on Jul 2, 2021

Thanks Joe, but we saw it today too. In fact, we saw it just a few minutes ago, on one of your earlier posts.

Maybe if you included it in every post, readers would eventually believe batteries aren't an obscene waste of money...is that the strategy? :-)

Michael Keller's picture
Michael Keller on Jul 3, 2021

Megawatt-hours (energy) is the relevant measure, not megawatts (power). Providing 75 megawatts for a few minutes is not particularly helpful. Providing 75 megawatts for 4 hours can be helpful (300 megawatt-hours).

Batteries can be somewhat helpful over short periods. The problems mount when a lot of peaking energy is needed for hours on end for months and months.

Joe Deely's picture
Joe Deely on Jul 3, 2021

No - wrong.

Sure MWh are interesting but at this point in time MW are more important.

For example, on the CAISO grid in the summer of 2021 it would be better to have 4000 MW of storage with a duration of 2 hours vs  1000 MW of storage with a duration of 8 hours.

By the way never heard of “peaking energy” which is needed for  “hours on  end for months and months”. Can you point us to the source of these peaks that last for 2000 hours?  Also, isn’t that more of a plateau?

Michael Keller's picture
Michael Keller on Jul 7, 2021

You are seriously deficient in technical and energy knowledge.

Meeting peaking demands nearly every day of the year for several hours a day works out to be a lot of ENERGY. A plant(s) that supplies 1000 megawatts for only a few minutes is more or less useless for sustained use to meet peaks that routinely emerge in the grid. For instance, multiple hour peaks that habitually show up in the evening when solar energy is offline because the the planet has rotated away from the sun.

Joe Deely's picture
Joe Deely on Jul 8, 2021

A plant(s) that supplies 1000 megawatts for only a few minutes is more or less useless for sustained use to meet peaks that routinely emerge in the grid.

Are actually replying to something I said with this? or is this just a standard cut and paste for you?

Something I done learned in the second grade - a few minutes does not equal 2 hours.

Also 4,000 = 4x greater than 1,000

Do you see how that works? Perhaps arithmetic is different in the Land of Oz.

Or...maybe you just need to read what I said before commenting.

Michael Keller's picture
Michael Keller on Jul 3, 2021

The CPUC is doing their best to make electricity a luxury item for the poor and middle class. Further, their actions are utterly irrelevant to climate change as simple mathematics easily demonstrates - relative to world-wide CO2 emissions, California is pure bug dust. Further, the assumption of man made CO2 having any meaningful impact on the climate remains conjecture.

The CPUC actions have been ill conceived and not particularly bright, as they are primarily kowtowing to environmental zealots, at the expense of providing the population with affordable energy. You have a bunch of like minded individuals suffering from severe tunnel vision and group think. Couple that with the arrogance of unaccountable bureaucrats and the result is predictable. Exorbitant energy prices and an intermittent and unreliable electrical grid. Welcome to California, a third world country of the extremely rich and the poor.

Joe Deely's picture
Joe Deely on Jul 3, 2021

Further, the assumption of man made CO2 having any meaningful impact on the climate remains conjecture.

 We’ve seen  similar arguments in the past from the folks fighting pollution controls on coal plants.  

‘Hey - what’s a little mercury between friends?”

“You can’t prove that’s “our NOx.”  

“So a little coal ash got into the river, big deal”

Curious - were you employed by Westar? Perhaps the wrong side of the below? Tough loss, eh?

https://www.epa.gov/enforcement/westar-energy-inc-settlement

You heard here first- you’re gonna lose again.

Michael Keller's picture
Michael Keller on Jul 7, 2021

Pollution and it’s impacts are reasonably quantifiable.  The impacts of CO2 are not and remain difficult to forecast with any degree of certainty, particularly when trying to separate from natural phenomena.

I have never worked for Westar or Kansas City Power and Light.

Suggest you refrain from slurs.

Joe Deely's picture
Joe Deely on Jul 9, 2021

Pollution and it’s impacts are reasonably quantifiable.

And yet you still advocate for more of the same. Says a lot.

 

Suggest you refrain from slurs.

Well, I definitely won't call you an environmental zealot. You could care less about the environment.

How about a pollution zealot?

 

David Pope's picture
David Pope on Jul 1, 2021

John,

Nice post, John, I'm glad to see others talking about not only the duck curve, but all the other curves associated with all the different types of generation.  In addition to the sources of generation we also have to understand that forecast the impact of battery storage capabilities as those start to be added to the power grid as well.   All of which requires a different or better approach to forecasting across all departments including load forecastings.   I wrote a blog on this which entitled: Utilities, forget the Duck Curve, and get ready for the Turducken Curve.  

Regards,
David

Jim Stack's picture
Jim Stack on Jul 2, 2021

John, excellent point on this issue that had plagued the GRID for 100 years. As you know the new advanced battery storage like the Tesla Mega Pack has this and many other load matching problems covered. It seems every utility around the world is adding battery storage. 

   It can help add renewable energy, balance the power mismatches and replace peak power plants that are very expensive and slow to react. 

    The cost on battery storage is falling as the life of the batteries increases. It is the holy grail for the GRID. 

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