Bill Gates seems to love to invest in things that aren’t going to make much of a difference to climate change but that are good for the fossil fuel industry. The latest is Heliogen, a company which uses machine learning to make solar ovens hotter and more reliable. The problems are rife with the technology and it’s not competitive except in niches that likely aren’t actually climate friendly.
This is the second of two articles assessing this technology. It introduced five problems with the technology as an industrial component:
- It’s a single, poorly scalable disk of high temperature
- Tight coupling of energy production to energy consumption
- Industrial facilities cast big shadows
- Very high heat doesn’t store or transmit easily
- We have solutions already that are much easier to integrate into industrial plants
The first article covered the first two points, showing that tying this to, for example, a single reasonably sized cement plant would require roughly 4,000 times the space, and that decoupling energy creation from demand would provide substantially more flexibility and higher value. Now we’ll step through the remaining three problems.
Industrial facilities cast big shadows
You’ll note from the Heliogen demo site that the tower is casting shadows across the array of mirrors. As noted, it’s about 55 feet tall based on the image, not an unusual height for industrial facilities for those of us who have been near them.
But industrial facilities are a lot more solid and wider than the Heliogen tower. They are going to cast a much bigger shadow. That requires the concentrating mirrors to be further away from the facility or a lot more loss of useful generation of heat during hours of the day when the sun is lower in the sky, which is to say further away from noonday summer sunlight. Basically it just adds to the engineering and land use costs to find some niche where this is actually as opposed to hypothetically useful.
This doesn’t particularly get better as concentrating solar power scales, as the concentration point typically rises further and further above the ground, both increasing shadows from infrastructure and requiring the heat to be moved further with attendant quality degradation. Ivanpah’s tower, for example, is about 460 feet or 144 meters in height.
That’s problem number 3, that the shadows diminish further the economically viable use cases. It’s not insurmountable, just drives this further into niche categories.
Very high heat doesn’t store or transmit easily
So this is the next problem. As stated, maximum temperatures are only going to be achievable for a portion of sunlight hours, with diminishing heat available in shoulder hours. There are certainly stores for heat, but the higher the temperatures, the greater the engineering challenges.
When we get up into the 1,000-1,500 degrees Celsius range, normal pumps and pipes just get soft and deform, which is a significant limitation. Only recently was a low volume 1,400 degree ceramic pump demonstrated in a lab that didn’t shatter due to its brittle nature. The machine was incredibly high tolerance, hasn’t been proven to scale and screams ‘expensive’.
And as soon as you drop the temperature down to the range that metals are comfortable with, you lose a lot of the benefits, and you certainly lose the 1,000 degree + mark. Molten salts run from 150 degrees C to 600 degrees. It’s possible to combine them to get higher temperatures, but then you start running into the same challenges.
Heat 55 feet off the ground and on one side only isn’t that useful to most industrial processes. Typically heat is useful below and in the middle of industrial plants. That means you have to transmit it for it to be useful. That disk of extremely hot temperature isn’t directly useful in most applications, so it’s going to be heating up some heat exchange medium which will transmit the heat downward and inward in a facility, losing its temperature along the way.
And heat is only useful on the site where it’s generated for a relatively short period of time before it degrades further below the level of usefulness. Heat escapes and can’t be transmitted long distances.
By comparison, it’s trivial to deliver electricity from hundreds of miles away and have it power heat sources in directly the location that they are required. In fact, it’s probably more efficient than transmitting heat 100 meters end to end.
So that’s problem number 4 with Heliogen’s hypothetical industrial component. It doesn’t put heat where it’s useful, the very high temperature is very hard to transmit even a few dozen meters to where it is useful, and it’s currently incredibly difficult to store anything at that high a temperature. It’s certainly possible to engineer an industrial solution around this, but it’s hard to imagine how without increasing the shadow problem mentioned earlier. Basically, every industrial plant would have to be designed from the ground up to work with Heliogen technology, or they could just bolt in electrical heat sources in convenient locations.
We have solutions already that are much easier to integrate into industrial plants
Is Heliogen uniquely capable of providing high temperatures? No, not at all. Obviously, we’re doing this today in multiple ways. A lot of heat is provided by fossil fuels, but an awful lot is provided by electricity too.
Let’s look at a couple of examples. Electric steel minimills are a good one. They use electric arcs to maintain temperatures of 1,800 degrees Celsius, well above the range Heliogen thinks that it might be able to achieve, and electric arcs can produce heat up to 3,000 degrees. Minimills currently provide about 70% of the steel used in North America without any problem at all. They’ve displaced most of North America’s steel manufacturing from iron ore with provision of high quality steel from scrap.
The same week that Heliogen made its announcement, Energywire carried a story about a new electric steel minimill being built in Sedalia, Missouri. What’s so special about it? Well, it’s going to run entirely off of renewable electricity. They’ve contracted for entirely renewable electricity, and more wind generation capacity is being added regionally to accommodate their demands.
Now that’s a model that makes sense. Put the plant where it is economically sensible to put the plant. Use incredibly well known, highly efficient technology for heat sources powered by electricity. Put the renewable generation where it makes sense to put the renewables. Run the electricity through existing transmission and distribution lines from generation to the plant. Don’t tightly couple them.
What other example springs to mind? Well, once again in the same week as Heliogen’s announcement, another steel innovation came to the forefront. Steel from scrap via electric minimills covers one part of the process, but doesn’t cover new steel from iron ore. That’s been proposed to be significantly decarbonized by using hydrogen in the process. Currently, coking coal is mostly used to iron ore reduction. When replaced with hydrogen, that eliminates CO2 from one major step and emits only water.
And how is the hydrogen to be created? From renewably generated electricity. Siemens has provided an industrial scale PEM hydrogen production machine for the facility, but the electricity is once again coming from wherever the renewable energy is generated over efficient transmission lines.
I reached out to Mark Z. Jacobson of Stanford, assuming that he and his team would have assessed concentrating solar power in some depth. He concurred.
“I don’t see the technology as filling any gap that was not filled previously, just another method of producing high temperature heat from renewable energy. Other methods of producing high-temperature heat from renewables include from electric resistance furnaces, electric induction furnaces, and electric arc furnaces, all powered by wind, water, or solar electricity. Whereas, Heliogen’s apparatus can produce temperatures up to 1,500C, an electric resistance furnace can produce temperatures of up to 3,000 C, so twice those of this new technology.”
All of which begs the question about Heliogen being useful for hydrogen production as well, another use case that it mentions. PEM hydrolysis is already 80% plus efficient and renewable generation to PEM device including transmission losses only drops that by a bit. If the proposed high temperature creation of hydrogen that Heliogen points to is useful, that heat can be supplied by electric arcs just as readily and without all of the other problems inherent in tight coupling of concentrating solar power to industrial facilities.
What does this all mean?
Well, it means that Heliogen has done some really cool machine learning to provide better alignment and capacity factors for a technology which continues not to prove that useful otherwise. I’m not downplaying the technical advancement. I’m sure that there are some industrial niches where Heliogen’s solution will be useful and economically viable, although I think it’s more likely that its core machine learning innovation regarding halo focusing will find a completely different niche outside of concentrated solar.
But the technology isn’t suitable for the vast majority of industrial facilities and their need for high quality heat. There are better alternatives, and systemically, electricity from renewables is far superior than direct use of the heat.
What would characterize a use case that this type of component would fit into? Well, it would have to be something where heat was required in the middle of nowhere where lots of land was cheaply available. It wouldn’t need incredibly high temperatures, just highly elevated ones. It wouldn’t require bulky above ground industrial facilities. It would have to be poorly served by grid connectivity, otherwise it would be simpler to just get electricity from widely spread renewables and use that with existing components that use electricity to provide high quality heat where required in the process. Even then, it’s going to need electricity to operate the neural net, the cameras and the drives the focus the mirrors, just not as much as heat would require.
What does that sound like to me? Steam assisted gravity drainage (SAGD) enhanced oil recovery for the oil sands. The oil sands in Alberta inject steam a couple of thousand feet underground through pipes with holes along their lengths to loosen up the oil trapped in the sand and allow it to be extracted through another hole nearby. The oil sands currently use co-generation gas units for this purpose, using the waste heat to create steam to inject underground, powering anything electrical with some of the electricity and selling the rest of the electricity to the utilities.
That’s right, once again, Gates has invested in a company whose only apparent natural market is for pumping more oil out of the ground that we can’t afford to burn. It might be a lower carbon way of getting at that oil, but we can’t afford to burn the very easily and cheaply recoverable oil, never mind most of what’s in oil sands right now.
And, once again, Bill Gates is spending his money and influence on dubious side bets instead of sensible technologies. Like Terrapower, Carbon Engineering, and solar geoengineering, Bill Gates is spending his money and influence in ways that aren’t beneficial to combating climate change. As I’ve said before, he needs new energy and climate advisors.
- Ivanpah Solar Power Facility – Wikipedia
- Press Release: Heliogen achieves breakthrough temperatures from concentrated sunlight for industrial processes
- Ceramic pump moves molten metal at a record 1,400 degrees Celsius: Device could store energy from renewables
- Electricity is the future for all energy
- Molten Salts: Thermal Energy Storage and Heat Transfer Media
- U.S. readies first wind-powered steel plant
- World’s largest “green” hydrogen pilot commences operation
- Assessment of hydrogen direct reduction for fossil-free steelmaking
- Bill Gates Is Throwing Away Money On Ill-Advised Non-Solutions To Global Warming
- Market potential of solar thermal enhanced oil recovery-a techno-economic model for Issaran oil field in Egypt
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