This is an exceptionally good article published originally in the Economist. It completes our understanding of where we are going with all this and actually is very encouraging. The hydrogen fusion part of the reaction is far more believable than other proposed protocols because the comparable momentum of boron to hydrogen is large enough to suggest a much lower energy expense in achieving fusion.
The result is that we break up a boron atom into high energy helium and no nasties. It is almost too good to be true.
Anyway, This article will go a long way to helping all of us understand just why this can work and also why now after all the effort spent over the past forty years. Both methods do look very close to success. And that is likely to be the most important thing to so far happen in this century. It will never be free energy, but I can settle with the next best thing and the swift end of carbon based energy technology.
Do not invest in coal plants for the long haul. This going to be resolved a lot quicker than anyone presently imagines.
October 25, 2009
The Economist has positive coverage of dense plasma focus fusion.
http://nextbigfuture.com/2009/10/positive-mainstream-reviews-of-dense.html
Mr Lerner’s machine is called a dense plasma focus fusion device. It works by storing charge in capacitors and then discharging the accumulated electricity rapidly through electrodes bathed in a gas held at low pressure. The electrodes are arranged as a central positively charged anode surrounded by smaller negatively charged cathodes.
When the capacitors are discharged, electrons flow through the gas, knocking the electrons away from the atomic nuclei and thus transforming it into a plasma. By compressing this plasma using electromagnetic forces, Mr Lerner and his colleagues at Lawrenceville Plasma Physics, in New Jersey (the firm he started in order to pursue this research) have created a plasmoid. This is a tiny bubble of plasma that might be made so hot that it could initiate certain sorts of fusion. The nuclei in the plasmoid, so the theory goes, would be moving so fast that when they hit each other they would overcome their mutual electrostatic repulsion and merge. If, of course, they were the right type of nuclei.
For the test run, Mr Lerner used deuterium, a heavy isotope of hydrogen, as the gas. This is the proposed fuel for big fusion reactors, such as the $12 billion International Thermonuclear Experimental Reactor being built at Cadarache in France and the $4 billion National Ignition Facility at Livermore, California. It is not, however, what he proposes to use in the end. In fact his trick (and the reason why it might be possible to produce a nuclear reaction in such a small piece of apparatus) is that what he does propose is not really fusion at all. Rather, it is a very unusual form of nuclear fission. Normal fission involves breaking uranium or plutonium atoms up by hitting them with neutrons. The reaction Mr Lerner proposes would break up boron atoms by hitting them with protons (the nuclei of normal hydrogen atoms). This process is known technically, and somewhat perversely, as aneutronic fusion. The reason is that the boron and hydrogen nuclei do, indeed, fuse. But the whole thing then breaks up into three helium nuclei, releasing a lot of energy at the same time. Unlike the sort of fusion done in big machines, which squeeze heavy hydrogen nuclei together, no neutrons are released in this reaction.
From an energy-generation point of view, that is good. Because neutrons have no electric charge they tend to escape from the apparatus, taking energy with them. Helium nuclei are positively charged and thus easier to rein in using an electric field, in order to strip them of their energy. That also means they cannot damage the walls of the apparatus, since they do not fly through them, and makes the whole operation less radioactive, and thus safer.
The plasmoids Mr Lerner has come up with are not yet hot enough to sustain even aneutronic fusion. But he has proved the principle. If he can get his machine to the point where it is busting up boron atoms, he might have something that could be converted into a viable technology—and the search for El Dorado would be over.
Department of Defence study of energy security mentions Polywell (Inertial electrostatic fusion) fusion in the abstract (84 page pdf) (H/T IECfusiontech)
Findings of multiple Department of Defense (DoD) studies and other sources indicate that the United States faces a cluster of significant security threats caused by how the country obtains, distributes, and uses energy. This paper explores the nature and magnitude of the security threats as related to energy—some potential solutions, which include technical, political, and programmatic options; and some alternative futures the nation may face depending upon various choices of actions and assumptions. Specific emerging options addressed include Polywell fusion, renewable fuel from waste and algae cultivation, all-electric vehicle fl eets, highly-efficient heat engines, and special military energy considerations
The DoD, and especially the DoN (Dept of the Navy), could benefit greatly from the potential of nuclear power. But nuclear fission power is expensive and presents ongoing safety concerns. A spinoff from a form of nuclear fusion developed in the 1960s by Farnsworth and Hirsch has achieved groundbreaking success recently. This Polywell fusion device was pioneered and scientifically demonstrated in 2005 by Robert W. Bussard. This type of fusion can use boron-11 and hydrogen as the fuel. Fusion of these elements produces no neutrons and no radioactive waste. Estimated cost to build a Polywell electric plant is less than that for a similar power-producing, combined-cycle gas plant or coal plant. A gigawatt-sized reactor would be a sphere about 15 meters in diameter. If all power for the United States were generated with boron-11 and hydrogen Polywell fusion, the total yearly requirement for boron would be less than 5% of current U.S. boron production and would cost less than two trainloads of coal at current prices for both commodities. A single coal plant requires a trainload every day for full-scale operation. The U.S. Navy could adapt such devices to ship propulsion and free ships from the tether of petroleum use and logistics. The Polywell device could enable very inexpensive and reliable access to space for DoD and the nation as a whole.
Nuclear Fusion—The Farnsworth-Hirsch Fusor
The DOE and international groups have invested hundreds of millions of dollars and decades on the tokamak approach. If all works well for the ITER, a fusion power plant will come online in 2050. However, a device derived from the Hirsch-Farnsworth fusor may enable operation of a fusion power plant to begin by 2015—or earlier.
Philo T. Farnsworth invented the electron tube technology that enabled television. He also discovered a technique to produce fusion with a sort of electron tube. The basic concept of the machine is the confi nement of energetically injected nuclei into a chamber containing a positive grid electrode and a concentrically interior negative grid electrode. The injected particles fly through a hole in the outer grid and accelerate toward the inner grid. Nuclei fuse when they collide with sufficient cross-sectional energy in the center of the machine. Particle-grid collisions limit obtainable output power. This fusion method is known as Inertial Electrostatic Confinement Fusion (IECF). Robert Hirsch joined Farnsworth in his lab and developed a more advanced version of IECF, which uses concentric spherical grids.
Tuck, Elmore, Watson, George Miley, D.C. Barnes, and Robert W. Bussard have extended the research. Many people have developed “fusors” (including a high-school student), which produce fusion from deuterium-deuterium reactions but do not produce net power. These devices have been used as compact neutron sources.
Nuclear Fusion—Bussard Polywell Fusion
Dr Robert W. Bussard published results in 2006 claiming that he had achieved 100,000 times better performance than had ever previously been achieved from an IECF device. Bussard’s machine replaces the physical grid electrodes with magnetic confinement of an electron gradient known as a “polywell” that accelerates the positive ion nuclei into the center of the negative gradient. His paper in the 2006 proceedings of the International Astronautical Congress states that he had developed a design based on his previous success that, if built, would produce net power from fusion. Bill Matthews’s article in Defense News covered the story in March 2007. In November of 2005, the machine achieved 100,000 times greater performance than any previous fusor. Analysis of those experimental results led Bussard to conclude that his design will produce net power.
Bussard’s company, EMCC, continues his work since his death in October 2007. Alan Boyle at MSNBC. com covered recent developments at EMCC in an online column in June 2008, and Tom Ligon, former Bussard employee, wrote a combination history and technical description published in 2008. Bussard referred to his confinement mechanism as “magnetic grid” confinement. The system has no actual, physical electrode grids, such as in the Farnsworth-Hirsch machines.
In Bussard’s concept of a net-power-producing machine, the high-energy fusion particles produced from fusion would directly convert their energy to electricity. The high-energy charged particles resulting from the fusion will fly toward an electrical-energy-capture grid (not used for particle confinement) and expend their energy by being decelerated by this grid, which will be tuned to the energy and charge of the fusion products. The high-energy particles need not actually impact the grid and heat it. Rather, they can decelerate as the electrical grid extracts energy from the charged particle’s motion, thus “pushing” a voltage onto the grid and yielding direct electric power from the fusion. About 25–35% of the power in this type of device will be in bremsstrahlung power, which will have to be thermally converted. The total power efficiency will probably be in the 60–75% range.
One of the great advantages of IECF is the potential to use boron and hydrogen as the fusing elements. In a Bussard fusor, a sphere—with a strong magnetic fi eld imposed on it and electrons injected into it—would develop a gradient of those electrons, such that the center of the sphere would appear to a positively charged particle as if it were a negatively charged electrode (somewhat like the electrode grid of the Hirsch-Farnsworth device). Positively charged nuclei of boron and hydrogen would be injected at appropriate angles into the sphere and would “fall” into the negative well of electrons toward this virtual anode at the center of the sphere. If the particles do not collide with each other, they will fly an oscillating path within the vessel by alternately traveling toward the center of the sphere and then out toward the sphere limits until the force of the “virtual” negative electrode at the center of the sphere again attracts the positively charged nuclei toward the center again. If the virtual electrode has sufficient power (about 156 kilovolts for boron/hydrogen fusion), when the hydrogen and boron nuclei collide, they will fuse. A high-energy carbon atom will be formed, which will instantly fission into a helium nucleus with 3.76 million eV of energy and a beryllium atom. The beryllium atom will instantly divide into two additional helium nuclei, each with 2.46 million eV of energy. Boron and hydrogen, when fused in this matter, produce 6.926 E13 joules/kilogram.
To place this ability in context, the United States consumed from all sources (e.g., nuclear, fossil fuel, and renewables) in 2007 approximately 107 exajoules (E18 joules). One hundred thousand kilograms of boron-11 with the proportional amount of hydrogen (which would be vastly smaller than the amount required for a “hydrogen economy”) could produce about seven times more energy than the United States consumed from all sources by all modes of consumption in 2007. Therefore, (assuming 100% efficiency for simplicity’s sake) about 120 metric tons (not 100 tonnes, because only boron-11, which is 80% of natural boron, gives the desired fusion with hydrogen) of amorphous boron would provide equivalent power for all U.S. energy needs for over 6 years. About 1.8 million metric tons of boric oxide (about 558,000 metric tons of boron) were consumed worldwide in 2005, and production and consumption continue to grow. The United States produces the majority of boron yearly, although Turkey reportedly has the largest reserve. At $2 per gram for 99% boron, the cost in raw boron to produce six times the United States 2007’s energy supply (not just utilities but all energy) would be $240 million (120,000 kilograms × $2.00/gram)—6 years worth of U.S. power for a little more than the price of coal to run one coal-fired power plant for 1 year.
If a Bussard power plant consumed one gram of boron-11 per second, this fusion rate would produce approximately 69 gigawatts, roughly the simultaneous power output of 69 major electric power generating plants—more than one tenth of all coal-plant power generation in the United States. About 320 kilograms of boron-11 fuel ($640,000 worth of boron) at one of these fusion plants would provide 1 year’s continuous power output at 700 megawatts. A typical coal-fired electric utility power plant nominally produces 500 megawatts of electricity, but it requires about 10,000 short tons of coal per day (a short ton is only about 91% the size of a metric ton). A short ton of coal for electric utilities cost around $56 in 2008. So, one day’s worth of coal for a single coal-fired plant cost about $560,000, and a year’s worth for a single plant cost over $204 million. The United States has approximately 600 coal-fired power plants, about 500 of which are run by utility companies for public power. A 500-gigawatt (or even larger) Polywell fusion plant (which could cost less than $500 million to build) built to replace a coal-fired plant will pay for itself by coal-cost savings in less than 3 years of operation if the charge per kilowatt-hour remains constant. Because the fusion plant has fewer moving parts and fewer parts in general, it should be less expensive to maintain and operate as well.
Over the past year, Bussard’s Company, EMCC, has built a new device to verify and extend the 2006 results. Contingent on continued funding, a prototype power plant with 100 megawatts of net power production could be built at a cost less than $300 million, and producing power within 5 years—perhaps as early as 2015. Because of the nature of this device, the power output versus input is directly proportional to the seventh power of the radius of the containment sphere. A 100-megawatt power producer requires a sphere about 3 meters in diameter. A gigawatt power producer would require a sphere approximately 15–20 meters in diameter. EMCC’s decade-ago designed machine size for a 100-megawatt generator to power a naval vessel is a cylinder about 20 feet in diameter and 30 feet in length.
With no way to convert a Bussard Polywell machine to a bomb, no radioactive waste produced, small relative size, ability to operate on abundant boron and hydrogen fuel, relatively inexpensive to build, and only moderate operational safety issues (high voltage and X-ray emission during operation), these machines offer a path to a magnum advance in civilization; elimination of the carbon emission aspect of climate change; a whole new realm of platform propulsion capability and deployed electricity abundance for the U.S. military; and abundant, inexpensive energy for all who adopt its use. These machines could be exported worldwide without concern that they would proliferate nuclear bomb technology.
