D. Industrial Heating
The easiest way to reduce worldwide industrial energy use is to realize that a portion of the goods that we make are unnecessary. We want to have products with modular replacement parts that snap into place. Engineering automobiles so that in time they shake and rub themselves apart is wrong from a climate perspective. Planned computer frame obsolescence is unwanted even if the computer chips inside keep changing, and I've noticed that certain 20 year old computer software programs still work remarkably well these days compared to their newer editions.
However, we still need some industrial output. We're the adults in the room and so we must consider how we're going to manufacture (or sometimes do without) every item that our human civilization needs with far less fuel consumption.
D1. Industrial preheating, between boiling water and steelmaking
A geothermal heat storage system can slowly preheat or fully heat any object on demand. Slowly preheating any object or fluid to an intermediate temperature will save at least a portion of the fuel needed to heat the object or fluid to its target temperature. Applying concentrated sunlight to almost any heating job can finish the heating process with approximately zero fuel use.
The only hard and fast upper temperature limit for long term geothermal heat storage is the temperature of an underground pool of molten lava. Natural pools of underground lava, or former lava formations that are cooling, have been known to exist in certain areas of the earth for decades on end. Hundreds of meters of rock can act as a powerful form of long-duration insulation around a lava pool.
If the lava pool is too hot the pool of liquid rock will start expanding until the lava can melt its way out of its pool.
D2. Facing up to a less dependable energy supply
Farmers are used to waiting If a field is too muddy to be planted then the planting just has to wait. If a drought or a blight kills this year's crop, steady customers just have to understand.
For that matter, industry sometimes has its own slowdowns when a critical component is stuck on a boat and doesn't show up in time or when the roads are blocked with three feet of snow. Texas in 2020 had a statewide rolling blackout for a week because their natural gas system wasn't properly winterized. So, it's at least possible for most energy-intensive industries to make slight accommodations for the vagarities of renewable energy if fossil fuel use is no longer a viable option. Optimally a plant's workers will get an occasional cloudiness holiday and the plant's warehouse has enough extra product in stock to tide the business over for a day or two.
That said, most energy-intensive industries will pay a bit more for a somewhat dependable seasonal source of high heat.
D3. Heating Wooden Pallets
Destructive wood-boring insects such as the Asian long-horned beetle have been hitchhiking rides across oceans inside the wood of wooden pallets. By law, wooden pallets now need to be heated to 160 degrees Fahrenheit for 30 minutes before first use and before re-use in international shipping. Some pallet sterilizing factories may heat thousands of pallets. A direct solar heating system using heliostats could displace fossil fuel on summer days. However, a pallet factory might sometimes want to perform a rush job during a cloudy stretch in November near Christmas.
It would make sense to build a pallet heating warehouse on top of a geothermal heat storage unit. A bit of the stored heat would naturally leak upward into the warehouse. Fill the warehouse with pallet-carrying trailers or design an assembly line of pallets. Move geothermal heat into the warehouse, give the pallets their required 30 minutes at the required temperature and then empty the warehouse for the next load. Overbuild capacity to handle some of the vagarities of renewable energy supply.
D4. Solar Metal Smelting
A perfect parabolic heliostat mirror can focus 1000 times the normal heating strength of the sun onto a tiny focal area, or 1000 flat heliostats can also achieve this heating strength. Solar heating to even higher temperatures is possible within a well-insulated enclosure. This amount of solar heat can quickly melt through steel. You can watch little home-based steel-melting solar experiments on the Internet. If you happen to be one of these Youtube or TikTok solar experimenters, you probably don't need me to tell you to be careful.
Because we can't choose where the best iron ores can be found, we might want to think about creating high temperature geothermal heat storage inside dry hills near iron ore deposits, for smelting steel.
It's possible to heat dry rock below the earth's surface to near-lava temperatures. Focus well-concentrated sunlight through as small an aperture as possible into a cavern perhaps 100 feet underground. It may take months or years of heating until ground temperatures near to steel smelting temperatures are reached. Block off the small aperture whenever the sun doesn't shine, to preserve heat.
A one ton bucket or a ten ton bucket of concentrated iron ore is first warmed in stages using concentrated solar heat, then is lowered down a shaft so that the bucket's bottom extends into the extremely hot. near-molten solar cavern. Between the cavern's high initial heat, additional concentrated sunlight flooding onto the ladle and possibly some additional fuel expenditures on a cloudy week, the iron in the bucket melts. As is typically done in steelmaking, the slag is scraped off, the carbon level of the steel is adjusted and then the steel is poured from the ladle into molds.
D5. Manufacturing ammonia
Ammonia has an enigmatic future. On the negative side, ammonia used as a nitrogen fertilizer is a major cause of atmospheric nitrogen dioxide, a long-lived greenhouse gas. Fertilizers in general tend to pollute rivers and create ocean dead zones so that the ocean waters don't sequester carbon well. Alternative biological methods of fixing nitrogen in the soil exist.
Currently, the world produces 175 million tons of ammonia per year. Ammonia production is responsible for 3% of global carbon emissions and 3 to 5% of natural gas consumption, so we could use some green chemistry here. Finally, ammonia has known toxicity problems.
On the positive side for ammonia, some researchers claim that it might be synthesized from atmospheric nitrogen gas and from water. A number of new methods for manufacturing ammonia require high-temperature heat, and here we might substitute geothermally stored solar heat for natural gas.
A tank of liquid ammonia is modestly stable while the ammonia stays in liquid form at -10 degrees F. under some pressure. Farm supply companies have figured this out. Ammonia might someday serve as a tertiary fuel source or as a transportation fuel. That's one reason why we might look into solar heat-prepared ammonia or possibly solar heat-prepared hydrocarbons.
https://www.science.org/content/article/ammonia-renewable-fuel-made-sun-air-and-water-could-power-globe-without-carbon
D6. In-Situ mining
It's possible to create a copper mine without much mining. Pour concentrated sunlight into the ground in order to greatly heat the ground. Drill wells so as to drain the ground thoroughly. Drill a few drainage wells across the bottom of the copper ore layer. Copper melts at 600 degrees Fahrenheit. Bronze age copper smelting was based on copper draining out of an ore at a high temperature. Good amounts of heated liquid copper should percolate downward out of the high temperature ore and it can then be pumped out of the drainage holes. I hope, but I don't know, that leaving the ground relatively undisturbed can minimize the worst of the pollution problems that copper mines typically have caused.
Even after the copper is almost all drained out of the heat sink, pumped away and sold, the seasonal geothermal heat store will continue to generate electricity on winter nights when the wind isn't blowing, in perpetuity, for centuries. This same high-temperature in-situ mining technique might work with other metal ores. Seasonal geothermal heat storage also has district-heating uses, another vast energy field.
D7. Solar Metal Smelting
A supply of stored high heat for steel smelting might be achieved. It's possible to heat a volume of dry rock well below the earth's surface to near-lava temperatures. Focus nearly parallel reflected sunlight down a long mine shaft and then through a small aperture into a small excavated cavern perhaps 100 feet underground for months or years until steel smelting temperatures are reached. Close off the small aperture when the sun doesn't shine. We want to minimize radiative heat coming back out of the mine and convective hot air coming up the mine shaft.
A ten ton ladle of concentrated iron ore is solar prewarmed in stages, then is lowered so that the ladle's bottom extends into the extremely hot, near-molten solar cavern. Between ladle preheating, the cavern's high initial heat, additional concentrated sunlight flooding onto the ladle and possibly some fuel expenditures on a cloudy week, the iron in the bucket melts. As is typically done in steelmaking, the slag is scraped off, the carbon level of the steel is adjusted and then the steel is poured from its ten ton ladle into molds.
At first, success is displacing 10% of the fuel used in a prototype steel smelting operation. Then we move on to 50% displacement, then 90%. With most heating applications a solar transition can be progressive.
D8. Solar source in-situ thermal mining
When a metal ore is heated, the metal liquefies and flows downward. Bronze age copper smelting was based on copper draining out of an ore at a high temperature. It's at least theoretically possible to create a geothermal copper mine or a tin mine without significant breaking of the ground's surface, without leaving a huge toxic open pit sore after the mine owner moves all profits offshore and then declares bankruptcy.
Drill a few copper drainage wells across the bottom of the copper ore layer. Drill wells so as to drain the entire local area of groundwater thoroughly. As before, seal the surface of the land against precipitation with clay, with waterproof runoff ditches and possibly with some thermal insulation. Pour concentrated sunlight into shafts dug into the ground in order to greatly heat the ground. Copper melts at about 300 degrees C. Good amounts of heated liquid copper should percolate downward out of the high temperature ore and the liquid ore can then be pumped out of the drainage holes. I hope, but I don't know, that leaving the ground relatively undisturbed can minimize the worst of the pollution problems that copper mines typically have caused. This same high-temperature in-situ mining technique might work with other in-situ metal ores.
Even after the copper metal is almost all drained out of the heat sink, pumped away and sold, the seasonal geothermal heat store can continue to generate electricity on winter nights when the wind isn't blowing, in perpetuity, for centuries. The entire seasonal geothermal heat storage apparatus used during the mining process can also have a second use, so that no heat used for mining needs to be lost in the long run.
D9. Incentives
For all industrial green processes used in a business-dominated marketplace, to move forward we need to see government integrity expressed in either strong incentives or disincentives, with a well-mapped research, development and ramp-up policy of replacing bad energy use with better systems. The 180 degree opposite of imposing incentives and disincentives is quiet but deliberate climate delay, which might suit a handful of fossil fuel company mogus just fine but it doesn't serve all of humanity at all.
D10. Carbon dioxide capture has verification risks
First, a caution. I'm a bit skeptical about any system of self-verification that a stream of pure carbon dioxide gas has been sequestered. It's terribly easy, and profitable if someone can get away with the scheme, to dump the stream of carbon dioxide back into the atmosphere rather than consume valuable and limited boreholes into basalt which have a limited storage capacity. For now I assume that in the early days of carbon dioxide capture, the captured carbon dioxide will displace the 7 million tons per year of carbon dioxide that humanity now manufactures. At some time in the future I assume that adequate verification standards will be established.
I note that numbers of corporations prefer to take an attitude that their previous greenhouse gas releases somehow won't count and that they need to focus only on sequestering their own company's current greenhouse gas releases and nothing else. Previous greenhouse gas releases are now setting off positive feedback loops such as our planet's thawing Arctic permafrost.
Current corporate practices color my opinion of carbon sequestration. Minor amounts of carbon dioxide are being captured out of the atmosphere, and then in most cases the CO2 is being sold off, used by industry and reintroduced to the atmosphere. In particular, captured CO2 is being used to extract more oil from existing fossil fuel wells, and I'd expect that this CO2 might escape back into the atmosphere, not to mention the carbon in the newly extracted oil. As a general principle, if bad corporate actors want to continue as bad actors then they'll have to soldier on without the climate movement's vital support.
That said, permanent carbon dioxide sequestration into common basalt formations is most likely becoming feasible. The sequestration part is approaching the realm of “better than nothing and affordable”. I'm willing to consider the possibility that good corporate or government actors might manage such a project. At present, capturing nearly pure carbon dioxide seems to be the stickier part of the process.
D11. Producing cement with solar heat and with carbon capture
Quicklime or calcium oxide, CaO, is currently created from limestone, CaCO3, by heating it above 825 degrees Celsius in kilns or in furnaces. CaO has many uses -- particularly it's used in the production of steel and concrete. Wikipedia estimates that a typical ratio of 1.3 tons of carbon dioxide is released for every ton of quicklime produced, and the world produces 280 million tons of quicklime each year.
For further reading: https://insideclimatenews.org/todaysclimate/concrete-is-worse-for-the-climate-than-flying-why-arent-more-people-talking-about-it/
For further reading see Heirloom Carbon Technologies: phys.org/news/2022-01-air-decarbonization-technologies-giant.html
I want a lime kiln that uses nearly 100% solar heat to reach a target temperature of 840 to 950 degrees Celsius. At the same time, a properly air-sealed solar kiln can capture a stream of pure carbon dioxide released by the heated limestone. Given a pipe full of pure CO2, the carbon dioxide can be sequestered in a basalt rock formation directly underneath the kiln. The planet might displace one gigaton of CO2 every three years with such a tool.
There's more. Quicklime, CaO, spontaneously absorbs CO2 out of the planet's atmosphere like a sponge, creating CaCo3, limestone. When a molecule of quicklime sits around in the presence of fresh air it eventually captures an atmospheric CO2 molecule and deteriorates back into calcium carbonate. Heating limestone, calcium carbonate, CaCO3, releases a molecule of carbon dioxide gas, CO2. So, a carbon-displacing quicklime plant can equally create CaO sponges that grab carbon dioxide out of the atmosphere and then we can sequester that collected CO2. I've read one recommendation that calcium looping is a fairly dependable method of carbon capture with few chemical side issues.
Calcium looping, also known as the regenerative calcium cycle, is heat-intensive. Because solar heat from heliostats is what we'll soon have in abundance, I recommend developing a closed cycle calcium loop for atmospheric carbon capture.
D12. CaO multiple cycle carbon sequestration modules
I previously described the design of heliostat arrays as an inexpensive source of the well-concentrated solar heat that we'll need to reach 840 to 950 degrees Celsius. Heating above 1000 degrees C creates a different, unwanted chemical.
Form follows function, and so I need to list every process that we need to do in the calcium cycle. The calcium oxide (quicklime) cycle has a carbon dioxide collection phase, a preheating phase, an atmospheric vacuum purging phase, a hot carbon dioxide release phase, possibly a final atmospheric vacuum purging of any remaining CO2 gas within the module and a cooling down phase.
In addition, the calcium oxide needs to be chemically processed every few cycles to deal with sulfur dioxide that has been sponged out of the atmosphere. Gypsum, a mineral composed of a calcium atom, a sulfur atom and hydrogen and oxygen atoms from water vapor, has immediate side-uses as a fertilizer and as drywall in house construction. Bonding sulfur dioxide out of the planet's lower atmosphere should be considered a minor benefit because it helps to reduce local asthma deaths.
During the atmospheric CO2 collection phase we want to efficiently push a great deal of outside air containing 420 ppm of carbon dioxide through the calcium oxide. We can use PV, wind turbine-powered fans or natural intermittent wind power to move the air. As with heat transfer from air to rock within a rockbed, we want to break up the airstream into 1000 tiny airstreams that are pushed quite slowly through a fixed miniscule distance that is filled with CaO particles the size of perhaps coarse sand or salt grains or perhaps as big as pea stone, particles just large enough to allow some air passage and then small enough for an enormous aggregate surface area with which the CO2 molecules in the air can react. Calcium Oxide is considered a salt, similar in physical structure to the more familiar sodium chloride, so manufacturing a container full of uniformly tiny salt grains is possible. I could see the possible manufacturing of elongated salt grains that would create more airspace for air passage through the grains, also a better ratio of air to grain contact area. Also, an array of steel air capillary tubes running from the air entrance side to the air exit side, coated with calcium oxide inside and out, would apply air quite carefully to the calcium oxide. Finally, some variation on an automobile catalytic converter design would work, substituting a layer of calcium oxide for platinum..
An integral part of the preheating and cooldown phases is residual heat transfer from a fully heated and processed CaO module to an ice-cold or a partly heated module full of CaCO3. We might run air in a loop from one hot but cooling module to one less-hot but warming module and back. In this process cool modules get marginally heated and red-hot modules get marginally cooled in stages. A multi-stage heat transfer process saves and re-uses much of our captured solar heat.
Below 825 degrees Celsius, CaO absorbs carbon dioxide. Above 825 degrees Celsius, CaCO3 releases carbon dioxide. We may want to boost each module to a final pre-cooking temperature where we preheat the module to 800 degrees.
Purging all of the atmospheric air out of a module might be accomplished within a cylinder with a hatch at one end. A vacuum pump can drain the cylinder of all air. Here we need even more heat to cook the CaCO3 from 800 degrees up past 850 degrees Celsius. The modules filled with CaCO3 will then exude carbon dioxide gas within the cylinder at these high temperatures. We then draw off the pure CO2 in a pipe.
With this description of processes, I can now design calcium oxide-containing modules. We must energy-efficiently apply good quantities of air past the calcium oxide salt grains, both for CO2 absorbtion and later for preheating and cooling down modules. We need entrance and exit air capillaries within the modules. The modules should withstand temperatures of 950 degrees Celsius of heating. The modules should roll into and out of a large high-vacuum cylinder that is equipped for hot carbon dioxide purging. Modules should come apart for periodic separation of the mineral gypsum from the calcium oxide. Finally, subsections of the modules should be easy for a robotic system to handle.
I see the module wafers as having many parallel slices of calcium oxide, with microperforated steel plates separating the slices. We may need a micropore filter material such as a fiberglass woven mat between the calcium oxide and the steel. The backs of half of the steel plates have an array of bumps that touch the flat outer steel plate of an adjoining module. These bumps create air spaces between adjoining module wafers and allow a gentle airflow through the wafers.
At the tops of an array unit of wafers are a supply air pipe and a return air pipe. Air coming through the supply pipe goes down every second air space. Air then drifts a standard, rather miniscule distance through one of the wafers, then rises up through an adjacent air space to the return air pipe.
Quicklime can be a caustic dust. These cylinder-shaped modules should only have an input pipe and an output pipe, and during transport it should be difficult for any caustic dust to escape from the modules. Air filters are recommended when blowing atmospheric air through the modules.
It costs money to build anything skyward, and so I see a long set of tracks on which pickup robots move a great number of modules out to CO2 gathering racks and bring them back. Fans that send air through modules, if used, will be close to the modules.
I see multiple high heat trading areas connected by air pipes. Perhaps ten heat transfer module slots hold four warming modules and four cooling modules connected by air pipes and fans to each other. A circular rotating manifold with five positions directs which pairs of the ten modules exchange air for temperature equalization between that pair of modules. The last two slots give us downtime to unload one mainly heated and one mainly cooled module and replace both of them with fresh incoming module and a fresh red-hot module..
The CO2 extraction facility consists of an 800 degree Celsius solar preheating station and a 950 degree carbon dioxide extraction cylinder that can also create a vacuum. A production line of modules move on carriages through heat transfer stages, through the 800 degree unit, into the high temperature vacuum chamber unit, then back out through several heat trading areas. Then the processed modules go out for a relatively long carbon dioxide absorption stage. Occasionally modules are diverted to a gypsum extraction stage.
This same CO2 extraction facility can turn mass quantities of pulverized limestone from mines into quicklime while capturing the CO2 released in the process.
The vacuum chamber will most probably be long and cylinder-shaped. The end will swing away to allow modules in. The modules will be barrel-shaped to perfectly fit the cylinder. The wafers will be round and they will stack side-by-side within the horizontally oriented cylinder modules. The wafers will have a top side, and both a supply air pipe and a return air pipe will circulate air into and out of the module.
I could see a collection of large mirrored light tubes bringing in great quantities of solar heat for the preheating and carbon dioxide extraction units. I can see an argument for massive nearby solar heat storage so that many modules are all ready to be quickly run into the CO2 extraction unit for fast extraction.
All in all, the system will be optimized to handle a high volume of extraction of pure CO2 from the atmosphere or from raw limestone, right above a basalt formation where solar energy is abundant, at low lifetime production costs and with relatively zero lifetime nonrenewable energy use. .
D13. Facing up to the world's manufacture of carbon dioxide products
Currently the world directly manufactures, uses and releases 7 million tons of carbon dioxide back into the atmosphere per year. The fizz added to sugary soda is pressurized carbon dioxide. The ground fog used in theatrical productions is created by exposing dry ice to the air. And so, a portion of the world's uses of manufactured carbon dioxide are somewhat frivolous. Dry ice is also used for refrigeration of products during shipping. Perhaps CO2 manufacture and dispersal into the atmosphere should be taxed or otherwise disincentivized. We'll also want to work on our planet's manufacturing processes.
D14. Sequestering a pipe full of pure carbon dioxide
Given a supply of pure carbon dioxide gas within a pipe, sequestration advocates claim that it can be pressurized and pumped at high pressure deep into fracked basalt formations. The CO2 pressurization process will hopefully use intermittent energy when it's available. In a few months CO2 will mineralize into the rock formation and will stay there for many thousands of years. The world has far more basalt rock for this purpose than we will ever need. As long as we can get a pipe full of relatively pure CO2, we can sequester it.
The carbon capture plant would preferably be situated in an extremely sunny and reasonably hot climate, sitting directly on top of a basalt formation. Such places are common enough. A nearby port facility would be nice for shipping manufactured quicklime and related products worldwide.
The first result of this set of innovations will be hundreds of millions of tons of CO2 not released each year into the atmosphere by cement manufacture, and the relatively affordable sequestration of gigatons of CO2 using solar power.
For further reading: https://theconversation.com/direct-air-capture-how-advanced-is-technology-to-suck-up-carbon-dioxide-and-could-it-slow-climate-change-18926
For further reading: Clearing the air: Decarbonization technologies take a giant step forward. https://phys.org/news/2022-01-air-decarbonization-technologies-giant.html
