I had an email from a reader that in my last post about energy generation I had omitted Fusion energy, which they believed was a major energy solution technology. So, this week’s post is a more-geeky insight in to the problems of energy generation in the post fossil fuel era.
Our current renewable technologies are only a stop-gap measure as I stated in the last post. The actual generation of electricity through these technologies is clean and green but the manufacture of the technology (e.g., solar panels, wind towers, Ocean/tidal generators, etc.) that captures the energy and the moderate lifetime (25-50 years) use of these technologies means a lot of relatively toxic and really hard to recycle materials as their use period ends. Yes, current renewables are a great improvement over burning fossil fuels to heat water to steam to spin a steam turbine but they are not solving the problem of pollution from all its various sources that is a greater existential threat to world health and stability. Local use of renewables are also a great improvement over the grid system and until we develop a system that requires almost no mining and no waste, current renewable technology is what we are stuck with. Integrating these technologies with full recycle systems would also help immensely but that would also require a complete revamp in our economic approach. You should be getting a sense of the overall complexity of what a true sustainable revolution needs. And hopefully you understand more why I say it is a socio-cultural-psychological-spiritual change we need.
I have argued against nuclear fission technology, even if the electricity generated is practically pollution free, since the nuclear waste is a very long-term problem. It also suffers from the extensive technological need for massive mining pollution and extensive energy needs to produce the technology. These latter situations are also true for all the renewables. Energy and cost payback time ranges from 1-3 years for smaller renewable systems and 10-15 years for a nuclear facility with all of them having optimistic life use of about 50 years. Overall, this makes them positive overall but the pollution aspects are still decades long and an ongoing problem.
One of my engineering friends did a review of the materials needed for a wind tower. Quite an impressive list of materials from multiple mining sources, with substantial rare earth elements needed. (Rare earths react with other metallic and non-metallic elements to form compounds each of which has specific chemical behaviors. This makes them indispensable and non-replaceable in many electrical, optical, magnetic, and catalytic applications.) Most current renewable technologies involve a lot of aluminum and/or high-grade steel. Steel is primarily made of iron and carbon, but requires numerous many other alloying elements also get added to create myriad different grades of steel, including stainless steel with high chromium and nickel composition to resist corrosion.
Each 3-MW wind turbine needs: 335 tons of steel, 4.7 tons of copper, 1,200 tons of concrete (cement and aggregates), 3 tons of aluminum, 2 tons of rare earth elements, aluminum, zinc, molybdenum. When summed up, iron ore, carbon, nickel, manganese, copper, lithium, cobalt, aluminum, neodymium, praseodymium, dysprosium, terbium, glass fibre, crude oil for the polyester and epoxy resins and the cable insulation and the cooling oil in transformers, cement for concrete, the reality of our energy generation becomes quite staggering. Focusing merely on the electricity generated as most of my environmental friends do, misses out the front and back-end problems. Yes, they are better than burning fossil fuels, but they are not a panacea for all our environmental problems.
And the energy to create the renewable technology has to come from somewhere. What we need are discussions that are systemic in nature and not simplified single shot solutions that focus on the electricity generation alone while ignoring the bigger picture. The need for reliable and clean energy is our goal, but the cost effectiveness has to be another discussion. IF we are trying to make a profit then we are limiting ourselves. What we need is the mindset like the great Victorian-age sewer-building projects that put public health as the goal, not profit.
Having put a damper on the optimism about renewables, let me transition into the more esoteric forms of future energy. One of the dreams for many decades has been nuclear fusion technology. Fission technology merely uses high energy radioactive decay to heat water to power steam generators. Fusion gets energy from forcing atomic nuclei together with immense amounts of heat released, that can also heat water. The not so minor problem of fusion technology is the ‘Coulomb Barrier.’
As a kid I was always fascinated playing with strong magnets. It was almost like a challenge for my friends and me to be able to get the equal polarity ends of two magnets to actually touch each other. With weak magnets it was doable. But with strong magnets, you would feel the repulsing force as the ends got closer together and just when you thought you could force them to touch, it was like an invisible squashy piece of foam prevented you. If only we were strong enough, we could get the ends of strong magnets to touch as we could with weak magnets. Try it. That is similar to the Coulomb Barrier.
Magnetism is one thing, but getting two positively charged atoms to connect takes a lot of effort and/or energy. We have two forms of fusion, cold and hot fusion. We know how to do hot fusion, but cold fusion which is preferred, is a tad more elusive. I just said we can do hot fusion, but the problem is that the immense energy needed to fuse nuclei is almost the same as the energy released. And by the time the heat of the fusion release heats up steam for a turbine, it is a negative energy gain. That second law of physics (entropy) gets in the way, every time it seems.
The sun (like most stars) is a fusion generator that uses intense gravitational pressures at its core to force hydrogen nuclei together to form helium. If a star is large enough it can even force larger nuclei to merge. Under Super Nova conditions the intense energy of the explosion creates large and larger merging of atomic nuclei. You could say that all the elements were born in the core of massive stars and their destruction – we are literally composed of 4th generation star dust. To create the conditions within a star can be done within a device called a ‘Tokamak’ or a ‘Stellarator.’ We superheat hydrogen (or its isotopes, or lithium) within a donut shaped chamber to a plasma (gases that are so hot that electrons are freed from atomic nuclei) that circulate through the chamber.
Now inquiring minds might ask what kind of material do we have in the Tokamak (or Stellarator) that can withstand the extreme heat of a plasma (150 million degrees Celsius)? Even though the walls are made of Beryllium and Tungsten, they would melt if touched by the plasma, so the plasma is controlled by powerful electromagnets that prevent the solid chamber atoms from interacting with the plasma nuclei. However, this controlled fusion allows the walls to get really hot so that solution pipes on the outside of the Tokamak can capture this heat to create steam – yes, all that technology to push steam through a conventional turbine.
If your eyebrows are still raised, keeping the core of a plasma hot enough so fusion can occur while preventing the Tokamak walls from melting is a problem that is more so when instabilities at the plasma edge releases energy in short bursts instead of a steady flow (Stellarator are better at keeping the plasma controlled). The good news is that unlike nuclear fission energy plants that can go into meltdown if they fail (e.g., think Fukushima or Chernobyl), If a Tokamak or Stellarator failed then it would simply vaporize the building and immediate surrounding area. Hot fusion works, but, there’s always a but it seems, it is a long way from becoming mainstream, if ever.
Now we get to ‘Cold Fusion’ and Quantum energy. This post is already long and so to be continued in next post.
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