Nuclear-fusion power plants

For those of us without a graduate degree in high-energy plasma, here’s a wikipedia article which gives a brief description of muon-catalyzed fusion:

I’m curious, Stranger. What do you think about the Eavor system that’s been in the news the last few days:

I’m leery of “too good to be true” solutions, but this looks both reasonably green once the initial install is complete and, at a target price of $50/Mwh, very competitive at industrial scales. The one thing I haven’t seen is geographic viability (i.e., can one of these be set up in Florida with our geology).

Fusion used to be pretty much entirely in the hands of big governments. Everything was shared.

Now there are some smaller (though still big) companies looking into it, using the technology that was developed by governments. Thy may be coming along without having to give the public a press report on every milestone.

The two things that are game changers in fusion are computers and high temperature superconductors.

Keeping a plasma stable requires enormous amounts of constant changes to the magnetic fields, along with massive simulations, and computing power is finally catching up to those demands.

High temperature superconductors not only change the requirements and abilities, but also the fabrication. They are easier to use and deploy than traditional superconductors. This allows much quicker prototyping. Rather than spending decades building each iteration, now they are spending months.

I’m not familiar with Eavor but there is a long history with geothermal energy, and these projects rarely pan out to be as sustainable as initially promised. The Geysers, a complex of geothermal steam plants in the Northern Coastal Ranges, saw a peak production of 240 billion lbm of steam in 1987, but declined rapidly and has leveled off at 150 billion lbm of steam only with the injection of wastewater into the steam bed. Although this is probably sustainable for the foreseeable future, the need to deliver and inject wastewater detracts from net energy production, and at some point it may not be fiscally viable to maintain the steambed for energy production. It looks like there is a renewed plan to build more facilities at the Geysers as of 2020 to help facilitate phase out of hydrocarbon fuel power production but this would seem to be more politically motivated than technically feasible.

This is somewhat misleading. When you say fusion was “entirely in the hands of big governments,” what you mean is that research was actually being done by university-associated research labs like Sandia National Labs and Princeton Plasma Physics Lab, and private companies like General Atomics with government (and sometimes private) funding. These labs were (and still are) highly competitive and did not issue “a press report on every milestone”; in fact, the published literature was often lagging the latest research by a couple of years, which made it frustrating when multiple labs would go down the same blind alleys because of a lack of shared information.

In the ‘Seventies through the mid-‘Eighties, there was actually a lot of interest in fusion research by oil companies who saw the petroleum market potentially contracting and were looking for the next big revolution in energy research. They poured tens of millions into fusion research but quit because despite claims and the occasional advance it wasn’t showing any promise of being closer. Chevron is actually investing in several nuclear fusion startups again because they know that the future of oil is limited.

Computing power and high temperature superconductors are certainly ‘game-changers’ in terms of making a workable nuclear fusion power generation system more feasible economically; however, there are still fundamental hurdles that need to be overcome just to achieve sustainable over-unity fusion, much less extract useful power from it. There is a long history in nuclear fusion research of overestimating or overpromising on when over-unity fusion would be possible and completely failing to deliver because of new problems being discovered. When I was an eager young aspiring-to-be-a-physicist middle school student excited about fusion, the microwave-plasma-heating system of the ELMO bumpy torus was being touted in all of the pop science press as the fur-sure route to practical fusion; however, it turned out that interstitial heating the plasma created other problems and as far as I am aware no lab today is still pursuing this configuration.

There was more recently a Lockheed Skunkworks project promoting a working fusion reactor within five years, the EMC2 Polywell that Robert Bussard promoted just before his death based upon one test run that produced an excess of three energetic neutrons, and various other promises and promotions that have turned into so much hot air. The hot new topic in fusion power research in the past few years has been “artificial intelligence”, with companies like TAE Technologies promising that the ability to test a bunch of configurations and feed it into some machine learning algorithm would let it spit out an optimal configuration for stable fusion, which begs the question if they can find any stable configuration with their architecture.

And of course, this is what tech startup companies do; they promise the world because they need investors who want to believe so much that they’ll back something that sounds vaguely promising, a la Theranos or Jawbone. They may sincerely believe in their product or research enough to convince you of its feasibility, too, but they need to show actual evidence, not just wild projections based upon hopes and dreams before claiming that such a technology will be ready to deploy by some particular date. In short, when you hear tech startups spinning tales to astound about how fusion power is just around the corner, temper your enthusiasm and hold onto your wallet because history indicates that such claims are often overblown or even just outright technically unworkable.


For storage of solar power, what about electrolysis of water to produce hydrogen gas that can be burned like natural gas? Or even reduction of CO2 to produce methane?

Electrolysis is fairly inefficient, and storage of hydrogen is difficult.

Pumped hydro is pretty much the gold standard of energy storage, efficiency wise, but it’s not practical to do in many or most places.

As @k9bfriender notes, electrolysis is not especially efficient (60%-80% efficient in electrolysis of water to hydrogen and oxygen), although if solar panels are really cheap or easy to deploy remotely, say on ocean platforms, it may still be financially viable. The bigger problem is storage and transportation, as gaseous hydrogen has a very low mass density and will seep through any path it can find and even diffuse through many seemingly solid materials. All of that being said, a large scale plant that uses solar to electrolyze hydrogen and then bind it into some kind of liquid hydrocarbon fuel could potentially be a worthwhile means of producing a fungible, carbon-neutral transportation fuel like dimethyl ether (DME). But someone would have to develop and deploy that platform at a capital investment of hundreds of millions of dollars.

Reduction of CO2 from the atmosphere suffers the problem that it is a very small component of the atmosphere (<0.05%), and so this ends up being a limiting factor in how fast you can extract it or sequester it. Ideally, you’d convert methane to methanol or DME because these are more stable and easier to store (methane is a potent greenhouse gas). Of course, that takes energy, too, but if you are producing a surfeit of energy from solar power the losses may not be of concern.

Pumped storage hydropower can be really efficient but only on large scales, e.g. you need a large dammed lake or reservoir to make it worthwhile, and creating such structures has ecological impacts. Molten salt is also a good thermal energy storage medium which can be extracted by heat pump at high efficacy.

There are potentially a lot of ways to store excess solar energy, but the most efficient ones aside from batteries are not really scalable to home installations, and while conventional electrochemical batteries are scalable in concept, the costs and production limitations limit the practical ability to deploy them. Solid state batteries made of inexpensive constituents and supercapacitors could be potentially game-changing technologies in that regard but they’re still years way from practical deployment. Still, they are more likely to get to a level of functional maturity long before controlled nuclear fusion and should definitely be an area of energy research that is given a lot of focus and funding.


Mars surface pressure is only 0.0062 atm. I think the new rover on Mars is able to extract O2 from the martian atmosphere from CO2 even at that low pressure. Interesting technology.

Re: chemical storage, it makes more sense the longer you need to store it or the farther you need to move it. E.g. Japan plans to effectively import solar energy via ammonia. Fission fell out of favor there for some reason. The already-mentioned difficulty of compressing and storing hydrogen means that they come out ahead even with the additional energy required to make and liquefy the ammonia.

The bad joke in my crowd is that DAC gets easier every year.
I’m not hugely sanguine about direct air capture for the reasons you mention, but there’s been progress. Re: MeOH/DME* vs methane, one factor to consider is that they fit into different current uses and infrastructures. With DME being effectively a diesel drop-in. Whereas we are already pretty good at moving methane around with more resilience than the electrical grid. But leaks are a problem wrt GHG emissions, as you mentioned.

If anyone is curious about the chemistry, we make DME from methanol by effectively dehydrating it. Methanol can be made by reduction of CO2 with hydrogen, and is current practiced at the George Olah plant in Iceland. Methane, also from CO2 and H2, is via the Sabatier reaction, although the folks over at Opus 12 tell me they have some fancy catalytic membrane technology that works better. Most of the above should have wikipedia articles if anyone is interested in further reading.

*In my organic chemistry days, this is what we called the solvent dimethoxyethane. But for anyone confused at home, we’re talking about dimethyl ether here.

Heh, that’s grim. I know a lot or people including a number of prominent climatologists and Bill Gates have pinned their hopes for offsetting carbon emissions on direct air capture and sequestration but the scale (millions if not billions of plants would be required to make a significant dent on current emissions) and the energy requirements are prohibitive without some external energy source. I’m slightly more optimistic about extracting carbon dioxide from the ocean where the density is much higher, and at tropical latitudes using solar power for this makes sense but the scale problem remains. Ultimately, replanting areas that have been deforested and aggressively ending deforestation are more cost-effective but politically and logistically challenging. Point-of-source sequestration is more feasible at natural gas power plants although the net energy production is significantly reduced.

As you mentioned George Olah in passing, below is an interview with him in Technology Review regarding the “methanol economy”. Olah, of course, is not some crackpot or elder scientist spouting off about a fleeting notion in a field far feom his own; he was awarded the Nobel Prize in Chemistry in 1994 and has been working on alternative fuel synthesis for decades. His book, Beyond Oil and Gas: The Methanol Economy, is the leading policy resource in the area of methanol and dimethyl ether (DME) synthesis and is accessible enough for the layperson and energy policy enthusiast to follow, and makes an excellent case for methanol and DME as a transition fuel that can be easily swapped into the current liquid hydrocarbon fuels infrastructure and even into existing gasoline and diesel engines with pretty minimal modifications. As much as electric car advocates want to assume that we’re going to total electrify the transportation system in ten years, that just isn’t going to happen for the majority of the world where those changeover costs would be prohibitive, notwithstanding the logistical problems of ramping battery production on that scale and the severe limitations of accessible lithium and various rare earth elements needed for the manufacture of batteries and electrical control systems for them.