The 2013 Climate CoLab popular vote winners in the electricity category were Integral fast fission reactors and funding nuclear fusion projects that could succeed within ten years. The goal of the Climate CoLab is to harness the collective intelligence of thousands of people from all around the world to address global climate change.
Popular Choice (at large): It’s the 21st Century. Where’s My Fusion Reactor? submitted by Dennis Peterson
Popular Choice: Integral Fast Reactors Can Power The Planet submitted by Tom Blees
Nuclear Fusion sooner
Investment in high-risk, high-reward, low-cost research on a wide variety of approaches to nuclear fusion, focusing especially on those with the potential for very inexpensive energy production. X-Prizes for milestones, direct grants for early-stage research, knowledge sharing and open licensing.
The key to extremely cheap fusion is aneutronic fuel. Most fusion research uses deuterium and tritium, which is the easiest to achieve but produces high-energy neutrons. But there’s another option: fusion boron with hydrogen. The reaction produces three helium ions, plenty of x-rays, and nothing else. (While there is a small amount of neutron radiation from side reactions, it’s less than released by burning coal, which contains 2 ppm uranium.)
The lack of neutron radiation completely eliminates even low-level nuclear waste. But more importantly, the charged particles carrying the energy can be converted directly to electricity, without needing to heat a coolant which is then run through a turbine. This has the potential to dramatically reduce the capital cost of the powerplant.
The disadvantage of boron fusion is that it’s harder to achieve net power production than with D-T fusion (which of course isn’t there yet either). But there are several projects with the potential to get there in the near term.
Tri-Alpha Energy is a fairly secretive private company focusing on boron fusion, with over $140 million invested by venture capitalists, Goldman-Sachs, Microsoft’s Paul Allen, and most recently, the government of Russia. They hope to build a working demo plant by 2020, using direct conversion of the alpha particles to electricity
Focus fusion (Lawrenceville Plasma Physics) is the most transparent of fusion projects, making regular public reports of their successes, failures, and challenges. It’s also the least expensive of all fusion approaches.
Focus Fusion uses a device called the “plasma focus,” which has been used in research for several decades. In a paper published in Physics of Plasmas, the team has shown it has reached temperatures of 1.8 billion degrees C, well over the billion degrees required for boron fusion.
At this point, experiments are going well, and the team is scaling up the reaction, with higher input power and density. If no roadblocks are found, breakeven could occur within a year or two. Engineering a production reactor after that would require an additional $50 million and five years.
The device is pulsed, with energy output in the form of x-rays and a jet of charged particles. Electricity generation is simply a matter of aiming the jet through a coil, and capturing x-rays photoelectrically.
A typical focus fusion plant would fit in a shipping container, generate 5MW, cost half a million dollars, and produce electricity at a tenth the price of coal.
Inertial Electrostatic Confinement – Bussard’s Polywell. Robert Bussard was one of the early pioneers of the tokamak fusion reactor, the approach used by ITER. For over a decade he worked at the Navy on a new approach using electrostatic confinement, which he dubbed the Polywell. The project was canceled, but analysis of their last experiment showed good results, and after several years the project was restarted. The Navy isn’t talking much but it continues to renew funding, and there’s been additional research in academia, with recent conferences in Maryland and Australia.
Polywell power output scales up rapidly with the size of the reactor. A 2-meter reactor chamber would, in theory, accomplish net power for D-T fusion, and a 3-meter for boron. A demo reactor would cost several hundred million dollars.
Petawatt Picosecond Laser Fusion. According to theoretical studies (backed by experimental verification of the basic physics), a petawatt picosecond laser igniting uncompressed fuel from the side could accomplish boron fusion with only ten times the difficulty of D-T fusion (compared to 100,000 times as difficult with NIF’s spherical ignition). Papers project a 10,000x energy gain and electricity ten times cheaper than coal.
Lasers of the necessary beam quality have only become available in the past decade. The largest currently available is ten petawatts; to attempt this method we’ll need at least 60 petawatts.
Deuterium Fusion – MIT’s Levitated Dipole. Levitated Dipole turns the tokamak inside-out, with a solid superconducting levitating torus, and plasma magnetically contained around it. It’s a simple configuration that imitates the magnetic fields surrounding the Earth and Jupiter, creating a steady-state system in which any turbulence helps to compress the plasma.
Recently the Alcator C-Mod group at MIT proposed a much smaller, cheaper design, using advanced superconductors for stronger magnetic fields, modular construction, and the same FLIBE coolant used in some molten-salt fission designs. (The C-Mod already has the highest magnetic field and plasma pressure of any tokamak device.) Sadly, the Alcator C-Mod lost funding in recent cuts, with the government redirecting money towards ITER. There’s growing support in Congress to restore funding.
Lockheed-Martin recently presented, at Google SolveForX, an ongoing project attempting D-T fusion, with a 2020 target date for a 100MW reactor transportable by truck.
Helion Energy explores a midway point between tokamak (low density plasma, long confinement) and laser inertial fusion (high density, short confinement). It’s a linear device that collides two plasmas. A one-third-scale device was built with $5 million in funding, and Helion claims to have validated its approach.
More recently, Helion has received about $7 million in funds from the DOE, the DOD and NASA. The company hopes to raise another $2 million by next year, $35 million in 2015-17, and $200 million for its pilot plant.
General Fusion also works in that “middle ground” with a variant of magnetized target fusion. A vat of molten lead spins, opening a channel in the middle, through which two balls of plasma are injected and collide. Two hundred steam-powered pistons impact the outside of the chamber, and an acoustic shockwave compresses the plasma. Neutrons heat the lead, and some steam from the coolant is used to drive the pistons. The project is well-funded by private investment, in part by Jeff Bezos. The design is only feasible due to recent advances in computerized control systems, requiring microsecond precision which the company has already demonstrated.
The company believes it is on track to show proof of feasibility in 2013, actual net gain in 2016, and a working reactor in 2020. They expect to be cost-competitive with conventional coal.
Integral Fast Reactor
The integral fast reactor (IFR) is a type of complete closed nuclear power system that recycles its own waste so that the elements that are radioactive for tens of thousands of years are all consumed and converted into electricity and waste elements with short half-lives. IFRs are capable of using spent fuel from existing reactors (so-called “nuclear waste”) as well as old weapons material and even depleted uranium. The inert waste from this process can’t leach anything into the environment for thousands of years, yet its radiotoxicity will decline to levels below that of natural uranium ore in a few hundred years, so it essentially solves the nuclear waste problem. Whereas ordinary light-water reactors (LWRs) in use around the world today extract only about six-tenths of one percent of the energy in uranium, IFRs can utilize virtually all of it, making them over 150 times more efficient.
The IFR was developed at Argonne National Laboratory until 1994, when the program was defunded by congress just as it was finishing. The EBR-II reactor there ran for thirty years and proved every aspect of the system. The goal was to solve all the problems associated with nuclear power—safety, economics, proliferation, fuel issues, construction time, etc. The program was amazingly successful on all counts, yet the technology was shelved and virtually unknown until 2008 when it began to be publicized.
During the years of the Argonne IFR research, a consortium of major American companies led by General Electric (including Westinghouse, Bechtel, Raytheon, Babcock & Wilcox, etc.) worked at Argonne with the researchers there to design a commercial-scale fast reactor incorporating the principles of the IFR. The result was the PRISM reactor. In the ensuing years that design has been slightly altered and optimized. It is capable of an output of 300-350 MWe, about a third the amount of a big power plant. The PRISM is a modular system intended for mass production. They are ready to be built.