Wednesday, July 14, 2021

Solar and Wind

In 2016 I considered putting up an array of solar panels on my south roof. It was going to be an ideal situation - okay, I'm in New Hampshire, so there are not yet any ideal situations, but other than that - no trees blocking the roof; I was going to be replacing the roof and putting in new electric anyway, and so could deduct that amount from the estimate of whether it was worth it; there were subsidies, one state and one federal. There was some other factor, I think.  I recall there being four.  Ah well.  I apparently did not blog about it at the time.

Even with all the advantages in play, the payback period was going to be twelve years minimum, on equipment that had a twenty-year warranty. As we were quite certain we were going to move before twelve years, and didn't know how much it would increase the value of the home, we decided against it. Even if we had stayed, we would not have gone for it, I don't think. (We made the right choice.  The price of oil went down soon after, pushing the payback period out to sixteen years.)

I had a metal roof put on, and spoke with the installer about my computations. He thought my numbers were similar to what he was figuring for Vermont, where he usually did business. I shrugged that solar looked like it was more than one breakthrough away.  He agreed, but thought those might not be too long in coming. His understanding was that battery technology was going to improve enough to be one breakthrough.  Where the second one would come from he didn't know, but there were nominations. He mentioned at the end that he was talking about subsidy-free numbers.

It's five years later, and battery storage is much better, so maybe that's one breakthrough.  I thought of him this weekend, listening to two men in their thirties who worked for commercial solar installation companies on opposite coasts, New Hampshire and Washington. So, not prime sunshine. One was a child of suburban privilege, the other a blue-collar guy.  They had just been introduced and were comparing notes. Both had some irritation at Tesla for sucking up all the battery technology and air in the room, but both also thought it was doing good-enough exciting stuff, moving things forward. One detailed a particular program that had two subsidies offered for certain businesses, totaling about 56% of the cost.  The other marveled.  "You could do it easily with only one of those.  You might be able to get it done with no subsidies, if everything broke your way." While they both are likely to be optimistic about their field, both also make their daily bread this way and seemed to be crunching numbers pretty sternly.

Obligatory skepticism: I think the enthusiasts have overlooked intermittency and vulnerability. They didn't take into consideration that emergency vehicles and construction vehicles have different needs than Priuses. I think they have been over-optimistic about when technologies will come on line.  I think both federal and state governments have no business subsidising anything more than experimental or proof-of-concept enterprises. I am not surprised that we are not solar-dominant at this point. If you caught me last week before I had thought about it a little harder, I would have done my usual scoffing.  "Call me when it's here."

Yet I also believe that ideas are the infinite resource, and technology does improve over time. I posted two years ago an article suggesting the time has arrived in the Southwest, with a few other places marginal. People do keep working on this. Just because some wide-eyed innocents make me crazy with their optimism, and their ability to convince governments to spend money, it doesn't mean that real improvements aren't happening. Batteries do have other uses, and other folks interested in improving them.  Their price is 10% what it was ten years ago.

New Hampshire will be just about last to come on board, but I would bet that solar is becoming viable, non-subsidy viable, moving up from the southland. Wind is the natural pairing for solar, because it is windier at night and windier in the winter, but I don't know a thing about that. The bladeless wind farm looks intriguing, but I am not positioned to be either optimistic or pessimistic about its chances. Single events like the Texas storm don't move the dial much for me. The computations have to focus on long-term use, with protections against one-off events.  the one-offs themselves too easily dominate our thinking.

29 comments:

Unknown said...

It bothers me a little that some subsidies for solar are taxpayer funded and on net 'regressive' -- it's the folks with ready money to invest in it that are getting the benefits.

It bothers me quite a bit more that other subsidies are dollar-for-dollar higher electric bills averaged across everyone else, so those on limited income are paying more so that those who can afford solar on their roof get a subsidy. I once when low-income lived in a rental with baseboard electric heat, and an especially cold week in winter could mean a couple of weeks subsisting on beans and rice -- that with rooms only set to 60° and even then only when occupied. We splurged to keep the bathroom at 67° 24/7 thru the winter . . .

So although we've now got the ready cash and no intention of moving, I just find it unethical to go solar until the numbers make sense with no subsidy.

Mentioning this makes me unpopular when people start extolling their own solar systems. I am, however, in a region where a very high proportion of the electricity generation mix is hydro, so I'd be offsetting a renewable with a different renewable. Maybe it would make some difference in distant-region's reliance on peaking gas?

I've read of people trimming or removing trees that shaded their roofs in order to maximize their solar capacity, and when I've run the numbers for my own house (with summer AC in use) more shade wins in every scenario so far.

I also believe that the 'duck curve' is real, and a real (but not intractable) problem. Adding wind doesn't fix it, but more uptake of demand pricing might?

Christopher B said...

I think the enthusiasts have overlooked intermittency and vulnerability.

This ought to knock the whole thing down as the recent Texas experience proved quite dramatically. It's pretty much an absolute guarantee that when you *really need* the power, i.e. when it's cold and dark, solar ain't gonna be there and wind isn't much better. Unless you want people freezing to death in the dead of night, quite likely anywhere north of the Mason-Dixon in an extended outage, we're still going to need baseload power plants capable of powering the grid. If you gotta build them, you may as well run them so they earn their keep since nobody is willing to pay electric rates that include them as backup. Wind and solar are little more than subsidy collection devices.

David Foster said...

Battery technology may improve enough to economically store several hours worth of power, so that solar electricity generated during the peak of the day can be consumed in the evening when air conditioning loads are high (the 'duck curve'0...but you're not going to see economical battery storage good for a couple of weeks. And weather conditions with little sun/wind for extended periods do exist, as the Germans have discovered with their 'energy transition.' There are some things that can be done with demand shifting, but few of them are viable over extended periods.

So you need a source which is *dispatchable*, that you can get when you need it. This means gas-fired, and it means that the capital costs of that system must be borne by the whole grid even if it is used for only say 100 hours per year. I think it's quite possible that the politics will lead to skimping on the dispatchable sources in favor of ''green-ness', and we'll enter an era of unreliable electricity.

David Foster said...

(I've been doing some research on this field, for investment purposes as well as general interest) Here is a useful summary of battery system costs and trends:

https://www.nrel.gov/docs/fy19osti/73222.pdf

Note (page 9) that there are 2 separate components of the cost: the POWER cost, which depends on the rate at which the battery can be charged or discharged ($/kw) and the ENERGY cost, which depends on the amount of energy stored ($/kwh).

dmoelling said...

For perspective here are the New England electric grid sources as of this morning. (see New England ISO iso-ne on the web)

Total Fuel Mix: 66% Natural Gas, 24% nuclear, 6% renewables 4% Hydroelectric

Renewables 39% Refuse (burning garbage), 37% Wood (wood waste and chips), 20% Solar, 4% landfill gas and <1% wind.

So of the renewables only the combustion technologies (refuse, wood and landfill gas) are reliable.

Solar is just a tax farming business in New England today.

David Foster said...

Real-time electricity generation is available for several regions in the US, here:

https://www.electricitymap.org/zone/US-MIDA-PJM

California and Texas have disappeared from the map; they were there a few months ago.

Sam L. said...

A couple of days ago I saw a short video of a a Tesla driver stopped on a road and asking for gasoline. His battery was dead. Well, he had a Honda generator in his trunk, but without gas...

Zachriel said...

Christopher B: It's pretty much an absolute guarantee that when you *really need* the power, i.e. when it's cold and dark, solar ain't gonna be there and wind isn't much better.

Like most systems implementing green energy (including in Texas), the green energy has to be backed by dispatchable generation, such as natural gas. That doesn't mean the green energy isn't useful, as it reduces the amount of fossil fuels consumed overall, even though it is insufficient on its own to reach zero carbon emissions.

David Foster said...

" the green energy has to be backed by dispatchable generation, such as natural gas"...indeed, and the capital cost of that dispatchable generation continues whether or not it is being used...if the gas plant has a 30-year lifespan, then that cost (including interest) has to be recovered over that 30-year time period.

Yet a lot of supposedly-reputatble sources are announcing that *solar/wind is cheaper than gas*, and they are calculating this by simply dividing the costs by kwh generated, without concern for *when* these kwh are generated or the cost of the backup.

Zachriel said...

David Foster: Yet a lot of supposedly-reputatble sources are announcing that *solar/wind is cheaper than gas*, and they are calculating this by simply dividing the costs by kwh generated, without concern for *when* these kwh are generated or the cost of the backup.

Can't speak for others. Gas is the backup in most instances. The investment for solar is about 10x what it is for gas, but the operating costs for gas are about 10x what it is for solar due to the cost of fuel. If you reduce the fuel requirement by 50% by replacing it with solar, then the breakeven point is about 10 years, not including the cost of carbon emissions.

David Foster said...

Good source on capital costs of various generation modes, here:

https://www.eia.gov/analysis/studies/powerplants/capitalcost/pdf/capital_cost_AEO2020.pdf

A combined-cycle gas plant will run you $958 per kw of capacity, and a solar plant will run you $1331. But the solar plant will only have a capacity factor of maybe 15-20%, due to night, bad weather, etc, while the gas plant can run whenever it needs to, so you will get a lot less kw from the solar plant than from a gas plant with the same peak capacity.

Moreover, even if you have 100% backup capacity from the gas plant, it can't ramp up and down instantly, owing to thermal stresses. If solar is going to represent more than a few % of total grid capacity, it is going to need to include some level of battery storage, at least 2-3 hours worth at a guess, to be a good grid citizen.

The solar plant does save fuel...for an efficient CCGT gas plant, this runs 2-3 cents per kwh, depending on gas price, and about half a cent per kwh for variable operations & maintenance expenses.

I think it's clear that when all the factors are combined, solar will cost more. Bear in mind also that solar, wind, and batteries are dependent on certain critical minerals, and the great expansion of these technologies will lead to bottlenecks. See this analysis: https://iea.blob.core.windows.net/assets/24d5dfbb-a77a-4647-abcc-667867207f74/TheRoleofCriticalMineralsinCleanEnergyTransitions.pdf

Christopher B said...

Zachriel said...
Like most systems implementing green energy (including in Texas), the green energy has to be backed by dispatchable generation, such as natural gas. That doesn't mean the green energy isn't useful...


Again, as the Texas incident showed, any episodic power source not backed by continuous generation capability has extremely limited usefulness given the instability those sources cause in the grid as well as second-order effects that may result in disruption of other energy supplies. If you want to gamble your existence on solar + wind + batteries to generate your electric power, knock yourself out. Just don't expect the rest of us not huffing the 'green energy' glue to explicitly or implicitly subsidize your dice roll with tax credits or other direct payments, buybacks of power at inflated rates, or that you get to be connected to our grid as an emergency backstop.

as it reduces the amount of fossil fuels consumed overall, even though it is insufficient on its own to reach zero carbon emissions.

When 'green energy' folks start backing nuclear power generation, I'll believe this.

Zachriel said...

David Foster: A combined-cycle gas plant will run you $958 per kw of capacity, and a solar plant will run you $1331.

Using your numbers, and assuming stability in the natural gas market, payback is 25 years: $1331/($0.03 * 20% * 365 * 24), while reducing greenhouse emissions.

David Foster: Bear in mind also that solar, wind, and batteries are dependent on certain critical minerals

According to your source, solar primarily requires copper and silicon. There are sufficient reserves of both.

Christopher B: Again, as the Texas incident showed, any episodic power source not backed by continuous generation capability has extremely limited usefulness given the instability those sources cause in the grid as well as second-order effects that may result in disruption of other energy supplies.

Again, Texas WAS backed by natural gas. Wind was not expected to produce much if anything during winter months. The natural gas system failed.

Aggie said...

I can't ever see solar energy working out in the northern states, just in terms of available sun energy. We are more than a couple of step-changes in technology away from it ever being truly viable, and in my opinion, the benchmark should be nuclear power. Solar's chief attraction really is that it is portable - ideal for your little dacha.

What leaves me scratching my head is the block-headedness that our leaders have pursued in trying to get solar power over the public policy line. They try to convince the public by offering tax incentives to stick these things on your roof. But anybody with the intelligence to explore the idea, is going to conclude that a tax incentive is not proof of concept, quite the contrary. And praying for payout before a hailstorm comes is not a good risk, at least not in the central US.

Duke Energy has just committed to installing 250 MW of capacity in rural central Texas. Bravo. So realistically we'll have enough to power a few thousand homes - during the day.

What if, on the other hand, we had Walmart get on a campaign to install panels on the roofs of their gigantic stores? Poor people in the South go to Walmart during the day, just to get into the air conditioning they can't afford, and this would be a way to power the peak loads. Or how about this: Install solar panels in large car parks to afford shade for parked cars, another thing that's a terrible problem in the South.

Really, integrating solar power with peak load shaving to take some stress of the fossil-fuelled grids seems to me to be the most logically beneficial idea, and providing shade for broiling parked cars seems a better, more practical way to show the public the complicated advantages of pursuing alternative energy.

David Foster said...

Aggie..."What if, on the other hand, we had Walmart get on a campaign to install panels on the roofs of their gigantic stores? Poor people in the South go to Walmart during the day, just to get into the air conditioning they can't afford, and this would be a way to power the peak loads."

I I believe Walmart has actually been doing this to some extent. One problem is that the heavy air-conditioning loads continue in the evenings past the peak times of solar generation. See GE's post The California Duck Must Die, which shows how the addition of solar has shifted the demand curves in California:

https://www.ge.com/news/reports/california-duck-must-die-not-think

Assistant Village Idiot said...

Solar panels to shade parking lots sounds like a winner. What am I overlooking about this being a great idea?

Zachriel said...

Another interesting concept is to use the increasing number of car batteries and home batteries to buffer energy supply. They charge during peak solar hours, such as at charger stations at work or home solar installations, return power during peak usage hours, then top off their charge at night.

David Foster said...

re the minerals report: PV solar needs copper and aluminum (plus silicon, of course, also silver)...solar is inextricably linked to batteries, due to the intermittency, and is also linked to electric vehicles, since a big part of the argument for such vehicles is that they could run on low-or-no-CO2 energy. These technologies require cobalt, nickel, lithium, and rare earths. About 70% of the world's cobalt comes from the DRC (Congo), and more than 60% of the processing is done in China. Lithium from Australia, Chile, and China, but about 55% of the processing is done in China. For the rare earths, it's 60% mining and 90% of the processing done in China. See pages 30 & 31.

There is also a handy chart (p 126) showing which minerals are most exposed to political risk and high-emissions mining & processing practices.

Donna B. said...

@AVI - solar panels to shade parking lots.

This has been niggling at me for a few days. I am not an engineer or physical scientist, but I kept trying to imagine this in a Texas WalMart parking lot. First, I thought the structure to hold the solar panels and "plug them in" would be really expensive, especially for a 1 story parking structure.

And then I thought the panels are essentially collecting heat as energy. Am I wrong? If I'm not, parking a car in this type "shade" would either make no difference in the interior heat of the car or make it hotter. Unless I've got everything wrong/backwards (very likely), a parking lot structure in the northeast might be a viable thing.

Zachriel said...

Donna B: parking a car in this type "shade" would either make no difference in the interior heat of the car or make it hotter.

Like all dark-colored shades, solar panels do absorb and emit heat, but the heat will tend to dissipate in the surrounding air, leaving your car cool.
https://news-media.energysage.com/wp-content/uploads/2017/02/parking-canopies-1.jpg

Aggie said...

It would keep your car cooler, much cooler. Most of your car's temperature comes from the albedo-related heat transfer from its roof sheet metal, and the greenhouse effect of the sun on the glass. A simple cantilevered frame with commonplace insulation board installed under the panels would negate any albedo-related radiant heat issues.

But: Just imagine the transaction: It's 95°F in the shade. You drive to Walmart and see their new solar-panel array in front of the store, covering the Handicapped and Momma / Seniors slots and extending further. There are 100 parking slots available under the array and - one's open! You hit the slot, get out of your car. You're already in a better mood - the car's not going to be broiling when you come out. Last year you snorted when the newspaper ran an article about a solar farm near town. Now you look up in the shade at that panel. Solar power. Not so bad. Might be a good idea after all. It's doing something besides making a politician look good and costing me tax dollars. Hey guess what: If it's raining when you come out, you can load your stuff and not get wet.

David Foster said...

Aggie...very good marketing thinking! And once Store A had this feature, competitor B would be under considerable pressure to do the same.

The degree to which the construction costs (as well as the solar panels themselves) would be recovered by electricity savings is going to depend on the pricing structure of the local utility: if they have time-based pricing, then the economics work better if their highest rate periods overlap considerably with the hours of peak sun.

I do wonder about damage from hailstorms; might want to think carefully before doing this in an area where those are frequent.

David Foster said...

Back on the economics: Zachriel calculated the payback on solar when only the avoided operating costs (fuel plus variable ops & maintenance) are included. I think that once the solar (and wind) reach more than a small % of overall capacity, you're going to need some level of battery storage to give the gas plants time to adjust their output. (Remember, electrical supply and demand must be in exact balance *at all times*.) Say $500 worth of battery storage, which should buy you roughly 2 hours worth.

Batteries don't last as long as gas turbines or solar panels; 10 years seems like a reasonable assumption. I ran a case with 25 year life for the solar plant, 10 years for the batteries, cost of capital 4%. The incremental cost that would need be be recovered across the total customer base is about 1.7 cents per kwh.

In these models, only a small % of the total generation is being provided by the solar panels...about 28%...To get above that, you need to "overbuilt", ie to size the solar system to provide *more* than the peak required capacity. Some of this will be unused at peaks, but more will be available when the sun is low in the sky or partially clouded over. You generate more kwh from solar, but the cost per kwh will definitely be higher....considerably higher if you want to generate a majority of the total from solar/wind.

WSJ today has a piece on a bill in Illinois that would force shutdown of all coal plants by 2035 and all nat gas plants by 2045. Subsidies for the wind/solar plants are included.

Zachriel said...

David Foster: I think that once the solar (and wind) reach more than a small % of overall capacity, you're going to need some level of battery storage to give the gas plants time to adjust their output.

About 20% or so. Wind can help even out some of the fluctuations. You can overbuild solar, but you would just have excess during off-peak demand times. (Ramp times are much lower with newer gas plants.)

Solar and wind cannot currently replace all fossil fuels, but can be economical up to 20% of capacity at current fuel prices, not including the cost of carbon.

Assistant Village Idiot said...

Illinois - I am never a fan of "Let's paint ourselves into a corner, because those jibroneys don't know what's good for them" solutions.

Carbon questions should be referred to China first, India second. The US is largely irrelevant going forward. The advertising pitch is that the US should become a world leader in environmental issues, and other places will follow suit, either by inspiration or shaming. As this hasn't worked in anything else, I don't see why it should work for carbon mitigation either. I became convinced over two decades ago that most environmental causes are about people feeling better, not actually fixing anything. If it were the latter the focus would be on fresh water availability and overfishing.

Zachriel said...

Assistant Village Idiot: The US is largely irrelevant going forward. The advertising pitch is that the US should become a world leader in environmental issues, and other places will follow suit, either by inspiration or shaming.

The U.S. is hardly irrelevant as it is a leading hub of technology and innovation. By being the world leader in green technology, the U.S. won't have to buy green technology from others, but can sell or trade green technology.

Assistant Village Idiot: As this hasn't worked in anything else, I don't see why it should work for carbon mitigation either.

Of course it works. The U.S. has prospered at the center of a great trading network, mostly because of its constant innovation. But it's not without competition in the modern world.

stevo said...

I think the whole thing is rendered moot if, as I think, the entire notion that petrocarbons are destroying the climate is completely false.

Aggie said...

Well now, the Silicon Graybeard has pointed out something rather interesting today, that Solar Power is unlikely to get much bigger, and for an interesting reason: Because of a tendency, as more solar power becomes available in a given area, for the entire supply to become increasingly devalued. The phenomenon has already been seen, in California for example.

"A few lonely academics have been warning for years that solar power faces a fundamental challenge that could halt the industry’s breakneck growth. Simply put: the more solar you add to the grid, the less valuable it becomes. "

https://thesilicongraybeard.blogspot.com/2021/07/why-solar-power-isnt-likely-to-keep.html

Zachriel said...

Aggie: as more solar power becomes available in a given area, for the entire supply to become increasingly devalued.

That relates to the discussion above. Solar is a good option for reducing the use of natural gas when the sun shines, but can't completely replace other sources. Pairing a solar plant with the equivalent sized gas plant means the gas plant can stop using gas when the sun shines, but burns gas the rest of the time. Doubling the number of solar plants only leads to an excess of power during daylight hours.