The Worth-It Threshold – When gas or gas + renewables is as bad for climate as a coal plant

The following article dovetails nicely as support for several articles that are in the queue. Those articles will describe a global case of ill-advised groupthink about a future energy supply system consisting of unreliable wind and solar power generation. My interpretation is that the “100% renewables” goal is a seductive mirage that has been carefully created to solidify a growing dependence on an environmentally risky natural gas infrastructure that includes hydraulic fracturing, massive storage, high capacity pipelines, and numerous inefficient simple cycle generators run in a rapid response mode.

Wind and Solar’s Achilles’ Heel

The Methane Meltdown
at Porter Ranch

by Mike Conley & Tim Maloney

The following is an excerpt from an upcoming e-book “Let’s Run the Numbers”


“We need about 3,000 feet of altitude, we need flat land, we need 300 days of sunlight, and we need to be near a gas pipe. Because for all of these big utility-scale solar plants – whether it’s wind or solar – everybody is looking at gas as the supplementary fuel. The plants that we’re building, the wind plants and the solar plants, are gas plants.” 1

Robert F. Kennedy, Jr.
Environmental activist

Member of the board of Bright Source
Developers of the Ivanpah Solar Station
On the California / Nevada border
392 MW (peak) concentrated solar

Natural Gas – the polite term for methane

The methane leak in the Los Angeles suburb of Porter Ranch is America’s worst environmental disaster since the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. But even more troubling is the larger issue of “fugitive” methane, and what it means for our growing reliance on wind and solar energy.

Burning methane for energy produces about half the CO2 of coal, which is a good thing. But fugitive methane – the gas that leaks before it can be burned – is a powerful greenhouse gas, with 84X the Global Warming Potential (GWP) of CO2.

The big idea behind wind and solar farms is to fight global warming by reducing greenhouse gases. But since most of a farm’s power is actually generated by gas, the rationale for a massive build-out of utility-scale wind and solar hinges on the issue of fugitive methane.

That rationale just had a major meltdown at Porter Ranch.

But it’s natural . . .

Natural gas is about 90% methane, so when you see all those upbeat natural gas ads, that’s what they’re talking about – burning methane for fuel.

The nice thing about methane is that it’s a lot cleaner than coal. Coal toxins are legendary, plus there’s all that CO2. For the same amount of energy, burning methane releases about half the CO2, along with some water vapor. And that’s it.

That makes methane the back-up fuel of choice for renewable energy. Whenever wind and solar fail to deliver (which is most of the time), a gas turbine kicks in to make up the difference.

Like anything else in nature, wind and sunshine ebb and flow, come and go. And it’s the unreliability of these renewable fuels 2 that lowers the Capacity Factor (CF) of a typical U.S. solar farm to about 23% 3 of its Peak Capacity, which is the maximum power a farm can generate under ideal conditions.

To fill the yawning gap between the real and the ideal, methane must generate most of the farm’s “nameplate” power: A one-gigawatt solar farm with a 23% CF is actually a 770-megawatt gas plant enhanced by 230 megawatts of sunshine.

So with all due respect to Robert F. Kennedy, Jr., he was misstating the case. Because wind and sunshine are the supplementary fuels, not the gas.

The Worth-It Threshold

Wind and solar farms, and stand-alone gas plants, have what we call a Worth-It Threshold: Beyond a certain leak rate, you might as well be burning coal for all the good it’ll do you (global-warming-wise, not total-pollution-wise.)

The Worth-It Threshold isn’t an abrupt borderline between worth-it and not-worth-it, it’s the point where it’s totally not worth it. A third of the way there means that a third of the green energy benefits are gone.

The problem is, the average wind or solar farm generates carbon-free power in such a narrow margin of utility that even if the optimistic 1.6% national leak rate claimed by the gas industry is true, it’s enough to erode nearly half of the climate-saving advantages the ratepayers hoped to see.

We’ve developed two simple formulas to quickly determine if a renewables farm, or a gas plant, is as bad for global warming as coal. For a gas plant, we used the fuel efficiency of the turbine and the leak rate of the infrastructure fueling the plant. For gas-backed wind and solar, we used the farm’s Capacity Factor, the efficiency of the back-up turbine, and the leak rate. This is what we found:


The Worth-It Threshold is the point where a gas-backed wind or solar farm, or a “stand-alone” gas power plant, is as bad for global warming as a coal plant.

To determine the Worth-It Threshold of a gas-backed wind or solar farm, find the farm’s Capacity Factor (CF) on the horizontal axis (the bottom of the chart.) Go straight up to the Threshold line, then straight across to the left side of the chart. The leak rate at that point on the vertical axis is the farm’s Worth-It Threshold.

The Worth-It Threshold of a CCGT power plant (Combined-Cycle Gas Turbine) is typically 4%, based on 45% of the CO2 emissions rate from an equivalent coal-fired plant.

In Part Two, we’ll explore both formulas in depth, and what they imply for our clean energy decisions. We know that sounds awfully technical, but relax! The idea behind both formulas is actually very simple: We determine the best-case scenario, which is the “CO2 avoided” by using methane instead of coal, and we divide that by the worst-case scenario, which is the “CO2-equivalent” if all the methane we planned to use leaks before we can burn it as fuel.

Dividing the best case by the worst case gives us a leak percentage, which we call the Worth-It Threshold. Any leaks approaching or exceeding that threshold make the switch from a coal plant to a CCGT, or from a coal plant to gas-backed wind or solar, a useless gesture in the fight against global warming.

So the formulas are easy. The hard part is facing what they reveal.

An Inconvenient Truth 2.0

As promising as renewables may seem, the harsh reality is that gas-backed wind and solar are only marginally effective in the fight against global warming. And the narrow margin in which they operate can be reduced, cancelled, or even reversed by a minor leak in a complex infrastructure of wells, pipelines and storage facilities that is completely beyond the control of the renewables industry.

If that seems like we’re stepping on everyone’s Green Dream, then please understand that when it gets right down to it, Mother Nature doesn’t give a damn about anyone’s favorite technology.

She doesn’t care if some people think that nuclear power is awesome, or if others think it’s the work of the devil. And she doesn’t care if some people think that global warming is settled science, or if others think that it’s an anti-capitalist con game concocted by liberal academics angling for grant money.

She frankly doesn’t care what anyone thinks, hopes, or believes. All she cares about is objective reality, quantified by math and explored by science, both disciplines guided by a diligent respect for the true nature of things.

Thin ice in a warming world

If the purpose of renewables is to reduce our impact on global warming, then our formulas clearly show that the entire effort is skating on thin ice.

Energy is the lifeblood of civilization, the master commodity that underlies all economic activity. And as pleasant as the thought may be to power a global civilization with the capricious whims of Mother Nature, sustainable modern life requires terawatts – not megawatts, not gigawatts, but terawatts – of cheap, reliable, carbon-free and controllable baseload power. There is no other choice.

To be anything more than green ornaments of the fossil fuel industry, wind and solar companies will have to:

(a) Overbuild by at least 3X (and probably 6X or more) the thousands of farms they envision, on tens of thousands of square miles, with the hope that all those farms can eventually back each other up4 (and the stability of the grid does not bode well for this approach5), or

(b) Overbuild by 3X, while also constructing hundreds of Hoover Dam-sized “pumped-hydro” mass energy storage systems with trillions of cubic meters of water to back up the farms. In the middle of a biblical drought.

The road to 100% renewables runs through Porter Ranch

An all-renewables national infrastructure would cost tens of trillions of dollars (that’s trillions with a T), plus about 30,000 square miles of land (that’s miles, not acres.) Imagine the entire state of South Carolina carpeted by solar farms. And the equipment would have to be replaced every 20 years, if it lasts that long.

We’re not waxing hyperbolic – the scale of a self-supporting, interdependent, renewable energy buildout really is that enormous.6 And note that we said “interdependent,” not independent: Without gas backup, becalmed wind farms in North Dakota will have to rely on solar farms in sunny Arizona. Unless it’s cloudy. Or night.

And during the several decades it would take to get there, we’d have to rely on gas backup for wind and solar, the marginal utility of which is detailed below.

In case you think we’re overselling our point, here’s Robert F. Kennedy, Jr. again:

“We need about 3,000 feet of altitude, we need flat land, we need 300 days of sunlight, and we need to be near a gas pipe. Because for all of these big utility-scale solar plants – whether it’s wind or solar – everybody is looking at gas as the supplementary fuel. The plants that we’re building, the wind plants and the solar plants, are gas plants.”

Thank you, sir. We couldn’t have said it better ourselves.

Note: You can download a PDF of Wind and Solar’s Achilles’ Heel Part Two here. It’s a short read full of useful additional information, but it’s a bit lengthy for a blog post.



2. The term “renewable energy” is shorthand for “the energy produced with renewable fuels,” since the supply of fuel (sunshine, wind, wave power, etc.) is constantly replenished by nature.

3. Topaz Solar Farm in San Luis Obispo, CA:

4. The Solutions Project (Jacobson, et al):

5. Intergrating renewables on Gemany’s grid:
(note Fig. 25 Interventions)

6. “Let’s Run the Numbers” (Conley & Maloney):

About the authors:
Mike Conley is a writer based in Echo Park who’s been studying energy issues for several years

Tim Maloney is a retired community college professor of Electronics Technology and Machine Control.
BS Engineering Case Western Reserve University
MS Electrical Engineering University of Toledo
PhD Educational Psychology University of Toledo

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