ENERGY CONSUMPTION SHARES, 2023: Totals 93.59 quadrillion BTUs. There is a pie chart breakdown of the components. The fossil share is 83%, nuclear is 9%, solar and wind combined is 2.6% and other renewables is 6.4%. The other renewables -- in descending order of size -- are biomass, hydroelectric, and geothermal)

(Emphsis added. No explanation for the tiny 0.07 quad difference between this energy production figure of 102.83 quads and the below (next section) Table 1.2 value 102.76)

The Energy Consumption shares above is from the pie chart in https://www.eia.gov/energyexplained/us-energy-facts/|us-energy-facts

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83.9% of U.S energy production is fossil fuel, while wind and solar combine to only 2.3% ughh:
EIA Table 1.2 in interactive: https://www.eia.gov/totalenergy/data/browser/index.php?tbl=T01.02#/?f=A&start=200001
. . . in PDF: https://www.eia.gov/totalenergy/data/monthly/pdf/sec1_5.pdf
TABLE 1.2 PRIMARY ENERGY PRODUCTION BY SOURCE

In 2023, in quadrillion BTUs: Fossil fuels: 86.2325, Nuclear: 8.1008, Wind+solar: 2.3284, Other: 6.0979, Total: 102.7597
So as percentages of total, I calculate:
Fossil: 83.9%, Nuclear: 7.9%, Wind+Solar: 2.3%, everything else: 5.9%, Total energy: 100%

I'll have to dig into the important details. For example (#1#) on fossil fuel production, does that include net exports?
(#2#) And how does one assess the production of a fossil-fueled fired electric power plant (or nuclear power plant), that converts only about 40% of the energy content of the fuel into electrical energy (throwing the other 60% away), as compared to wind and solar that convert these resources straight into electricity? I know some info resources that convert say the 1 TWH output of a wind farm by multiplying it by, say, (100%/40%)= 2.5 TWH of equivalent primary energy. Then they convert to BTU at the theoretically perfect 3412 BTU/KWH (3.412 BTU per watthour) with the result of 8.53 trillion BTUS (or 0.00853 quadrillion BTUs) of equivalent primary energy.

The footnotes on this page probably explains #2 above (where will have to click on some of the links in the footnotes and then read all that crap, but yes, it appears that they do something like what I described above)
. . . https://www.eia.gov/energyexplained/us-energy-facts/

An Exajoule is 10^18 joules. An Exajoule is an SI unit of energy. To get the above quadrillion BTU numbers into Exajoules, multiply the above by 1.055056 EJ per quad. So, for example, the total energy 102.7597 quadrillion BTUs is 108.4172 Exajoules.

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Yesterday, I put this stuff at the bottom of the infamous post#3 in the Intersect Power thread, so its all together with the year-by-year U.S. power sector and U.S. totals stuff.

This shows the whole energy picture for 2022. Open it up in a new window, or, better yet, download it and look at it in some sort of “viewer” so you can look at it in detail.

https://flowcharts.llnl.gov/


Check out the gray mass, labeled “Rejected Energy” (upper right) this is wasted energy, and accounts for slightly more than ⅔’s of the "primary energy.” When you drive a fossil-fueled automobile, part of the energy in the fuel goes to moving the vehicle, part of it is lost to friction in the drivetrain, part of it to fighting wind resistance, most of it is lost in the form of heat from combustion. (Decades ago, I read that the average car radiator puts out enough heat to heat the average house. Cars have become more efficient since then, but not that much more efficient.)

Look at the “Transportation" sector of the flowchart (lower right.) Of 27.5 “Quads” (quadrillion BTU’s) flowing into “transportation” 21.7 is wasted. That’s more than ¾’s! Wasted! The same is largely true for fossil-fuel driven generation of electricity. An old coal-fired power plant is about ⅓ efficient. (⅔’s of the primary energy in the coal is wasted.) A newer gas-fired plant is about 45% efficient, wasting a little more than ½ the "primary energy." (EIA: More than 60% of energy used for electricity generation is lost in conversion.)


Energy from renewables can also be “rejected." What if solar panels or wind turbines are producing more electricity than is required at the moment? That excess electricity is lost, unless it is stored somehow — perhaps in a battery of some sort.

What does it mean that we waste ⅔’s of our “primary energy?” It means that if we could change our energy system to make it 100% efficient, not that we can, but, if we could, we wouldn't need to replace the full 100.3 “Quads" of “primary energy,” just about ⅓ of it!


Now, as I said, we cannot create a 100% efficient system (batteries for example are not 100% efficient, they give off heat when charging and discharging.) However, replacing horribly inefficient coal fired power plants with much more efficient photovoltaics with battery storage would require much less "primary energy” than our present system.

Last edited Tue Jul 23, 2024, 10:08 AM - Edit history (1)

Thanks much for the Lawrence Livermore flow diagrams and EIA info on efficiency. I haven't seen the LL flow diagrams posted here for a long time (years).

I see the footnote:

I don't know what the "typical fossil fuel plant rate" is that they use (I'm sure I can find that if I dig down enough), but I see in the graphic in https://www.eia.gov/energyexplained/us-energy-facts/ that 41% is used and 59% is lost (the black and gray box at the bottom center of the "U.S. energy consumption by source and sector, 2023" ),

then my example in post#1 using 40% is quite close. Using 41%, 1 TWH of electricity is equivalent to 1 TWH * 1.00/0.41 = 2.439 TWH of primary energy = 8.32 trillion BTUS (or 0.00832 quadrillion BTUs) of equivalent primary energy. Using the theoretical 100% 3.412 BTU per watt hour to convert the 2.439 TWH of primary energy into 8.32 trillion BTUs of primary energy.

The footnote goes on to say, for those reading the rest of the right half of the diagram,

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One clarification from my years as superintendant of operational planning at Northern States Power (NSP, now Xcel Energy) back in the 80's:

Once electrical energy is on the grid, it's part of the grid total. If the grid total supply exceeds demand, the result is that the system frequency starts to go up. Power plant governors (like in a car) sense the frequency deviation from normal and reduce output of the generators they control. This happens across the entire synchronously AC connected system -- in our case, the entire eastern 2/3 of the U.S. (minus, sigh, Texas) .

So the wind supplied electricity is not rejected (once its on the grid), but rather other generation automatically backs off.

The Eastern interconnection consists of a number of control areas. NSP's control area was basically southern Minnesota including the Twin Cities with some of western Wisconsin. Anyway each control area is responsible for keeping its supply and demand in balance. So what happens if the NSP control area has the offending excess generation? Its control center software will sum the net outflow of electricity on its tie lines to other utiliities, and send signals to control area generators to back off until the net outflow (or net inflow) is what it's supposed to be (scheduled exports minus scheduled imports).

Fine if we have generation that can be backed off, as usually is the case. So basically the energy from the wind generators backs off other generation in our control area. Generally not a bad thing since the wind, being free, is the cheapest resource on the grid (as is solar). (There is a small variable operation and maintenance (O&M) cost to generating). (As for the capital cost of constructing the wind turbine, that's a sunk cost, so it doesn't enter into operational economic decisions).

The automatic control generation keywords are AGC (Automatic Generation Control), and Economic Dispatch, and Equal Incremental Loading.

But what if it is during a night-time or other low-load period (spring weekends) and all the other generators are backed down all the way to their minimum generation setpoints? That means they can't be backed down any further. So we're up shit creek but we do have a paddle -- we can shut down a generating unit(s). Dispatchers aided with software figure out which generator(s) to shut down and when.

If it's one we would have shut down anyway (and restarted some time later), then no biggie -- we are just shutting it down a little earlier than planned and starting it up a little later than planned, typically.

Sometimes it’s a generator whose shutdown is being caused entirely by the wind (or solar) generation -- i.e. without the wind generation, we'd not shut down the unit. So because of the wind generation, we're paying the cost of a shutdown / startup cycle. That causes extra fuel to be burned to reheat the boiler (or keep it on hot standby), and it causes extra thermal stresses which we have estimates for the long term cost of, e.g. $25,000 per shutdown/startup cycle for a large coal unit (700 MW) back in the 1980's in 1980$.

The above is discussing generation other than the wind and solar (I'll just use wind as an example that applies to both). Well, what about shutting down the wind generation when it is causing unwanted and costly shutdowns of some of our units?

Now I'm in dunno for sure territory -- my experience is before we had any wind or solar. But I read that some wind generators can be shut down by facing their rotors into the wind and rotating the pitch of the blades so they are straight-on into the wind, so that the passing wind does not exert a torque on the blades. So the rotor doesn't spin and the attached generator doesn't spin either, so we have no electricity output. Great, problem solved.

But apparently this capability makes wind generators considerably more expensive, I guess, because a lot of them don't have this capability. So for these wind generators, they just generate when the wind blows. To avoid expensive unwanted shutdowns of other (non-wind) generation, we can play "Let's Make A Deal" and try to sell the excess generation to another utitlity. Fine if we can. Not fine if we can't.

Next up, "Let's Make Another Kind Of Deal" and offer to PAY THE OTHER UTILITY to take our excess energy. If they can come up with a (negative) price that costs us less to get rid of the excess energy that way than by shutting down some unit(s), then that's the way to go.

The other utility (if they are honest about their production costs) will incur costs to shut down some unit of their's, but they may have a unit they can shut down at lower cost (considering the whole shutdown startup cycle) than we can, so that's how the deal works out for both parties.

I've seen a lot of articles about e.g. California utitilies "selling" excess solar and wind energy at negative prices to neighboring southwestern utilities.

Why can't we just open the electrical circuit on a wind generator (if it doesn't have the capability to turn its blades into a zero torque position)? Because without electrical load, and with some wind, the rotor will just spin faster and faster and faster, destroying itself. Because there is no "back EMF" electromagnetic force countering the generator-rotor when the circuit is open.

(Don't ask me what happens if the circuit is opened by accident or if an electrical fault (short circuit) appears and the circuit must be opened to clear that fault -- I would think that happens frequently in a world of tens of thousands (a guess) of wind turbines - they must have some mechanism to lock the rotors, but if they do, why don't they do that in normal operations in the situations described above where there is excess generation causing problems? Unless it's so stressful that its only done in emergencies)

As for solar, I don't know that they do. It's mostly solar energy that California sells at a loss (at times) to neighboring utilities, so I read, so they apparently can't simply just open the circuit and all is well. I guess that solar panels they use just heat up to destructive temperatures if energy is not dissipated by energy flow out as electricity. I guess. I don't know.

All's I know is that if there were a simple way to shut down solar generation, they would, because that is cheaper than paying a neighboring utility to take the surplus energy.

Another possibility is dump resistors. At the Navy nuclear test site in Idaho, they dumped their electricity into resistor banks that were submerged in tanks in a circulating water system, creating steam that made clouds visible for tens of miles.

I've never read about that being done by utilities getting rid of excess electrical energy. Or anything useful like using the electricity for hydrogen production.

That's all I know or don't know.

Additionally, re wind energy efficiency: it doesn't convert all the wind passing thru the circle swept by the blades. Similarly with solar energy and the sun striking the solar panels.

But is the wind and solar that is not converted wasted? Or a lost opportunity cost? Or just a challenge to improve the hardware and design to reduce the capital and material costs per KWH of electricity produced?

My question:

I chose its "professional tone" and "long" answer. All underlining and emphasis is mine.

The reply:

California's approach to managing surplus solar energy is a complex issue that involves various economic, technical, and regulatory factors. The state often generates more solar energy than it can consume, especially during peak production hours. This overproduction can lead to what is known as the "duck curve," where the supply of solar energy exceeds demand during certain times of the day. To manage this, California exports excess electricity to neighboring states, sometimes at a loss, due to the lack of sufficient energy storage capacity and the challenges associated with rapidly shutting down and restarting solar farms.

Opening the circuit of a solar farm is not a trivial matter; it involves more than just flipping a switch. Solar farms are integrated into the power grid with considerations for grid stability and energy continuity. Abruptly disconnecting a solar farm can cause voltage fluctuations and reliability issues within the grid. Moreover, the infrastructure for storing excess energy is still catching up with the production capabilities. The state has been investing in battery storage technology to store excess energy, but the current capacity is not enough to handle the surplus generated on the sunniest days.

Financial incentives for solar energy production have also been reduced in an attempt to slow the rate of new solar installations, which contributes to the surplus. However, this is a short-term solution to a long-term problem. The ideal solution would involve enhancing the energy storage infrastructure, improving grid management technologies, and possibly reforming energy market policies to create more flexible and efficient ways to handle surplus energy.

California's experience serves as a case study for other regions increasing their renewable energy capacity. It highlights the need for advancements in energy storage and grid management to fully harness the potential of renewable energy sources. As the technology and infrastructure improve, it is expected that the management of surplus energy will become more efficient, reducing the need to sell excess at a loss or curtail production.

A previous medium length answer said also that there are state incentives for increased renewable energy production or something like that. To me, that implies that maybe the state incentive is larger at times than what they have to pay the other utility to take the energy. Dunno, more questions than answers as always.

I can't figure out how to ask this version of Copilot follow up questions. It used to be easy to do.

I think they can hook up groups of solar panels so that they can bring on or take off a few MW's at a time, and so as not to have to suddenly dump hundreds of MW's in an instant.

I'm going to post this now, but I'll be trying to ask follow up questions one way or another.

My question:

Copilot's answer: (all emphasis mine)

California's approach to managing surplus solar energy involves selling it to neighboring utilities, sometimes at a loss, due to a combination of factors including the state's high solar production, the timing of peak solar generation versus demand, and limitations in current energy storage technology. The phenomenon known as the "duck curve" illustrates the mismatch between peak solar production and peak demand, particularly during spring when energy demand is lower. This overproduction leads to situations where California has more solar energy than it can use or store, necessitating the sale or curtailment of this excess energy.

The idea of simply opening the solar farm's circuit to avoid generating surplus is not a practical solution due to the potential risks and inefficiencies associated with abruptly disconnecting large-scale solar generation from the grid. Solar farms are integrated into the power grid with considerations for grid stability and reliability. Sudden disconnections could lead to voltage fluctuations or power quality issues that might affect the broader electrical system.

Modulating the output of solar panels by grouping them and controlling their circuits is a strategy that is already in use to some extent. Technologies such as Maximum Power Point Tracking (MPPT) and Pulse Width Modulation (PWM) are employed to optimize the efficiency of solar panels and manage their output. MPPT, for example, allows solar farms to adjust the voltage and current to maximize power output under varying conditions. However, these technologies are primarily designed to optimize performance rather than to reduce output to zero.

((blah blah about more battery storage and transmission needed -Progree))

As for adding follow-up questions, in a typical conversational setting, you would simply ask additional questions in subsequent messages. However, since this is a text generation mode, the focus is on generating a comprehensive response to your initial query. If you have further questions or need clarification on a different aspect, you would present those as new, separate inquiries. Each question would be addressed individually to provide detailed and informative responses within the scope of the conversation. If you're looking to modify your question or expand upon it, you would present the modified or additional information, and a response would be generated accordingly, taking into account the new context provided.

Sigh. I just don't have all day to dick around. I've had about 4 earlier Copilot sessions on different subjects and have not been satisfied.

I would also like to tackle the issue of reducing or zeroing the electrical output of wind turbines that my post #5 above gets into.

And yes, I know AI Q&A produces greenhouse gasses much more than traditional Google or Bing searches

The federal government offers a production tax credit of 2.75 cents per KwH for the first 10 years of a solar power plant's life. So as long as a power plant is not paying someone more than 2.75 cents per KwH to take their power, they'll get reimbursed the full amount of their loss and then some at the end of the year.

“… s the wind and solar that is not converted wasted? Or a lost opportunity cost?”

I see this as a difference without a distinction. Electricity which is generated, but not used, is a lost opportunity, and a waste.

We need a better distribution system, and fast. There’s always some place that needs electricity. If you cannot store it for use at a more opportune time, selling it (at a profit) is an attractive alternative. Giving it away is less appealing. Paying others to take it off your hands is indicative of a serious problem. (California is not the only state that faces this quandary.)

What I meant with "not converted" is that the wind turbine blades simply do not capture all the wind passing through the swept circle, or solar panels do not convert every watthour of incoming solar energy striking the panel into electricity, due to technological limitations of those devices (some day these will be improved by better blade design and solar panel design). What I meant was the part not converted to electricity at all because of the technological limitations of these devices.

Anything and everything converted to electricity becomes part of the grid (since we don't use devices like dump resistors or any other such way to throw away electricity, AFAIK). This electricity, once introduced into the grid is physically undifferentiated from other electricity. So in a sense it can't be wasted. What it can do is cause wasteful operations of the other power sources like a thermal generator that must undergo a costly (in terms of extra fuel burn and O&M) shutdown-startup cycle because of the excess electricity on the grid.

If it merely causes some thermal units for example to back off (generate at a lower output but still remain on line), then it's not wasteful in any sense of the word (fuel costs and emissions are reduced). Ditto if it causes a unit that would be shut down and started up anyway to shut down earlier and start up later (again, fuel costs and emissions are reduced).

What's truly wasteful besides undergoing an unnecessary and costly shutdown / startup of some other unit(s) is:

If the wind/solar output is sent to a dump resistor rather than to the grid. But AFAIK there aren't any such devices. So if the wind or solar device generates electricity, then out to the grid it goes. And other units on the grid have to back off, so the grid doesn't get into a sustained overfrequency condition. (Turbine generators are designed to operate within a tight frequency band. Also utilities are required by law to maintain an average 60 hz operation in the U.S.)

If we curtail the wind turbine output by turning the blades so that it is less efficient or so the blades don't turn at all, and/or if we open-circuit some solar panels. No electricity is generated, but could have been. That is wasteful.

If we settle for wind and solar devices that are good and efficient, but could be better but we decide we don't want to pay the additional capital cost for one that is more efficient, then that is a waste (up to a point -- if the saved capital cost is spent on something that has a higher return on greenhouse gas emissions savings per dollar invested, then that is the way to go)

Yes, yes, yes, yes, and yes. (I think I got them all).

Occasionally I see a post chortling ecstatically about (wholesale marginal) electricity prices going negative on the grid, like it's a great thing. But as you say, it is indicative of a serious problem (the marketplace of other utilities is willing to be paid to take the electricity even though it causes inefficient costly operational changes)

I promised them that I would vote for whoever I thought had the best climate policy. I reasoned that if our stances on the climate were similar, our stances on other issues would be as well. (I still have my Inslee T-Shirt.)

After Inslee, I liked Harris’ climate record…

Here’s a bit of a January, 2019 article from PBS:
https://www.pbs.org/newshour/politics/what-does-kamala-harris-believe-where-the-candidate-stands-on-9-issues

Thanks for posting this. You should cross post to GD.