JP said…

“You obviously know what you are talking about regarding Tokamak research. What are your views on Inertial Confinement Fusion driven by lasers?”

I believe that Tokamak fusion could be brought online as a power source feeding the grid easily within ten years and perhaps as few as five if we were willing to make the national commitment (and I do believe that it is in our countries interest to do so).

I do not believe laser driven inertial confinement fusion is likely to be a viable method of generating electricity from nuclear fusion within the next three decades, however, I can’t rule out the unexpected breakthrough.

Here are the reasons for my belief. Plasma physics as they apply to Tokamak fusion reactors are sufficiently well understood that building a reactor that will confine a plasma at the necessary temperature, density, and for the necessary time is entirely doable today.

Until recently there were two large questions that needed to be answered. First, can superconductive magnets be manufactured that could create the necessary magnetic fields for long term plasma confinement?

The second question, what materials hold up to constant neutron and ion bombardment? In addition to enduring the ion and neutron bombardment, it is also desirable to utilize materials with low neutron activation potential to minimize radioactive waste from neutron activated materials when the reactor is retired.

Unlike a fission reactor in which neutron embrittlement of the reactor vessel will eventually necessitate retirement, it isn’t clear that this will ever be the case for a fusion reactor. The penalty for a failed reactor vessel is far less serious in the case of a fusion reactor owing to the fact that it’s not holding tons of radioactive fission products and actinides.

The first question, whether or not it is possible to create a strong enough field for containment using superconductive magnets was answered by the Chinese EAST reactor when it saw first plasma in September of 2006. The answer was an unequivocal “Yes” because the superconductive coils at EAST functioned as designed providing plasma confinement.

Existing test reactors, prior to China’s EAST reactor, used copper coils for confinement magnets. The resistance of the copper winding caused them to rapidly heat up and limited operations to no more than 60 seconds. In addition copper coils waste a huge amount of power. Commercial reactors will use superconductive magnets to allow for sustained operation and to avoid wasting power.

The second question won’t be answered until we build a commercial power level reactor. EAST will be able to do some testing but at a power level of approximately 16 megawatts where commercial reactors will operate at power levels of 500 megawatts or more. One can try to extrapolate but when you’re dealing with a difference in power levels of 30x you really need to be able to test at the higher power levels.

Contrast this to the situation with laser driven inertial confinement fusion. In my opinion, the state of laser driven inertial confinement fusion is approximately where Tokamak fusion was in 1970. There are several major problems relating to laser driven inertial confinement fusion.

The first problem is that because this method relies on the implosion of a fuel pellet, the fuel pellet must be extremely symmetrical, to within a few microns, and the illumination by lasers must be extremely uniform. In practice the necessary uniformity of illumination has not been achievable.

The second problem is that the delivery of energy to the fuel pellet is extremely inefficient. The lasers themselves have proven to be inefficient. The wavelengths that can be generated by lasers at the necessary power levels are not efficient for heating the target so some method of increasing the frequency (decreasing the wavelength) is necessary. Presently, this is achieved through the use of optical frequency tripplers. The end result is that around 1.5% of the electricity used to fire the lasers ends up as useful laser output. Terrawatts of power are used to implode a fuel pellet that would provide the equivalent of a barrel of oil’s energy if all the fuel were fused. The energy economics just aren’t there without massive improvements.

Shortening the laser pulse increases the overall efficiency by concentrating the power during the time it is required for rapid heating and compression of the fuel pellet. But electrical engineering realities make this problematic. Wire has inductance, inductance limits the rate that current can rise. The operation of a laser also requires the presence of an optical resonant cavity; but a resonant cavity limits the sidebands necessary for a rapid pulse rise and fall. A lower Q cavity that would allow the necessary sideband frequencies results in less efficient laser operations. The same problem also exists in the optical frequency trippling device which involves an optically non-linear material and optical resonances.

The output is not consistent from one firing to the next, nor from beam to beam, and this creates issues with the even illumination of the target.

In inertial confinement fusion, the reaction area is extremely small, consequently the heat-load in that small area is tremendous. Tokamak’s represent a much more diffuse energy production source making heat removal less problematic (though still a tricky engineering question). Given that the problem of efficient heat removal is still present in Tokamak’s, the fact that it is many orders of magnitude greater in inertial confinement leads me to believe that it may be an problem for which no solution exists.

Then there is the problem of fuel. The most promising fuel for both types of reactor initially is a mixture of tritium and deuterium because this particular mixture has the lowest energy requirement to fuse. Deuterium is not a problem, one out of two thousand hydrogen atoms in seawater is a deuterium atom. There is enough deuterium to provide for our energy needs for 15 billion years at present energy consumption levels. Granted, those levels will increase and so perhaps it will only last a billion years. But by then I’m sure we can tap extraterrestrial sources of deuterium or perhaps be able to create the necessary conditions for fusion of ordinary hydrogen which is 2000x more plentiful.

Tritium does not occur in nature in substantial quantities. A very small amount is created by the bombardment of atoms in the upper atmosphere by cosmic rays.

In a Tokamak, the reactor vessel will be lined with a lithium blanket which will absorb neutrons and breed tritium in the process, thus solving two problems at once, that of preventing neutron activation and embrittlement of the reactor vessel and producing the tritium necessary for the reactors operation. Tritium also is created by neutrons bombarding deuterium present in the cooling water of fission reactors. There are engineering obstacles to using a similar lithium blanket in an inertial confinement reactor because of the much higher energy densities and heat loads.

In a Tokamak, a burning plasma, that is a plasma in which energy created by fusion reactions is sufficient to sustain the reaction indefinitely directly, is the desirable state, but it’s not absolutely necessary. As long as the output energy from fusion is sufficiently greater than the energy input required to cause it to take place after all the losses are considered, it can be commercially viable even without a burning plasma.

By contrast, a laser driven inertial confinement reaction will absolutely need to achieve a burning plasma condition to get a significant fuel burn because it is just not possible to concentrate enough laser power in a short enough time frame at a high enough efficiency to have a prayer of reaching scientific breakeven much less commercial breakeven otherwise.

In my view inertial confinement fusion is and will only be useful as an inefficient neutron source, and for research for the development of nuclear fusion weaponry. In short, a toy of the war mongers and not a viable peaceful energy source.

On the other hand, Tokamak fusion I believe is very much ready to be brought online. As I mentioned previously, the issue of whether or not superconductive magnets of sufficient strength could be manufactured was answered by China’s EAST reactor.

A second big question was could a diverter, a device that skims helium waste and removes it, withstand the bombardment by ions and neutrons. The primary issue was the heat load that would be generated by ion bombardment which would largely be due to what are known as localized edge mode instabilities. Recently a new technique has been developed that addresses the localized edge mode instabilities.

So with these two major problems largely addressed, there really aren’t any other known major hurdles. There may be some that we won’t know about until we have a plasma operating for hours or days but those will only be discovered with the building and operation of a commercial power level reactor. However, I feel optimistic that the way is now relatively clear.

With all of this said; there are a number of new schemes for producing fusion power that may ultimately prove to be far more economical and flexible than Tokamak reactors. Tokamak’s are by necessity physically large. They are too large and too heavy to find applications in transportation. Perhaps eventually they might be small enough to power say an aircraft carrier, cruise liner, or merchant cargo ship, but not airlines, trucks, automobiles, or even trains.

Tokamaks also probably will never be able to operate with aneutronic fuels. This is because reaching the necessary energies for fusion to occur thermally results in too large of a loss for temperatures higher than what are necessary for D-T fusion.

Other new configurations may allow for a reactor sufficiently compact and lightweight to find applications in transportation. I don’t know if they’ll ever fit in a Delorean but an airliner or train is a possibility.

I believe one of the most promising new designs is the Bussard inertial electrostatic confinement fusion reactor. This reactor uses magnetic fields to confine electrons only, thus creating an electrostatic well. The electrostatic well then confines and accelerates the ions. The beauty of this design is that electrons being much lighter than nuclei can be confined by relatively whimpy magnetic fields. The electrostatic well created then confines and accelerates the atomic nuclei which then collide and fuse.

This unit causes all of the nuclei to have the same energy at the center of the electrostatic well so that it can be tuned to the energy spectrum required for fusion and then all of the nuclei will be within that range. This is much different than in a Tokamak where you can only achieve an average energy but many nuclei will have either too much or not enough energy to fuse and both of these represented wasted energy.

The Bussard design has the potential to achieve fusion with aneutronic fuels eliminating the need for massive shielding while simultaneously allowing electricity to be directly tapped rather than thermally generated. It also has the potential to be made small enough for large trucks, buses, airliners, etc. Unfortunately, it’s development is currently not being funded and I find this to be almost criminal.

Another interesting design is the levitated dipole. This device also has the potential for achieving the necessary energies for aneutronic fuels to be fused, however, I do not feel it has to potential to be compact enough for most transportation applications. It’s really too early to know how much potential it has. The Bussard design by contrast has already been through six generations of test reactors, each one showing substantial gains over the previous.

An alternative to laser driven inertial confinement fusion is particle beam driven inertial confinement fusion. The particles in questions most frequently being heavy ions. The advantage of this over lasers is that a larger percentage of the input energy can be delivered to the target, however, ions being charged particles, have a natural tendency to diverge and not remain in a focused beam and that is a problem.

The Farnsworth fusor uses two concentric grids to accelerate deuterium ions towards the center of the device where a portion of them collide and fuse. This readily produces fusion but, not at sufficient power levels to be of commercial interest. The limitation on power level is the grids which are heated by ions colliding with them. The Bussard device gets around this problem by creating a virtual grid by steering electrons with a magnetic field.

There are numerous other methods of creating fusion at low power levels. Injecting deuterium gas into a nickel cylinder under high pressure results in some “cold fusion” where ions are absorbed into the nickel and fuse. The fusion rate is extremely low, too low for power generation and only marginal as a neutron source.

There is a method of creating some fusion using pyroelectric crystals. Methods using collapsing bubbles in acetone created with ultrasound. All of these do not generate sufficient fusion to generate power. They are useful as a neutron source and to study the physics involved but little else.

Right now, I believe that Tokamak fusion is sufficiently mature to be brought online in the near term. I do not believe any other fusion technology is sufficiently mature to be brought online as soon, but ultimately some of the other methods may prove superior when sufficently developed.

If the claim made in this video is true, this is very good news. It is claimed that the yield of biodiesel from algae is 217 times as much per acre as from rapeseed, a preferred crop for the purpose in the US. What is more it doesn’t need food producing land nor high quality water.

This guy scares me. He writes this long entitled, “A new dawn for nuclear power”.

In this article he states,

“To keep this process under control most reactors require a moderator – usually made of graphite or water because their light atoms are good at absorbing the kinetic energy of the neutrons.”

For those who are not familiar with the operation of a “thermal” nuclear reactor, that is to say a nuclear reactor in which the chain reaction is perpetuated by slow “thermal” neutrons, the function of a moderator is not to “keep the process under control”. The function of the moderator is to slow the neutrons down so that they can readily be absorbed by another U-235 atom and cause another fission. Faster neutrons are not as efficiently absorbed.

Control rods are used to keep the process under control by absorbing a portion of the neutrons above that which is required to achieve break-even (a sustained reaction rate in which each fissioning atom results in exactly one additional fission reaction on average).

So what is scary about this? People who don’t know what they’re talking about write articles all the time. Well here is what is scary.. In the about the author section it states that,

“Paul Norman runs the postgraduate MSc course in the physics and technology of nuclear reactors at the University of Birmingham, UK; Andrew Worrall and Kevin Hesketh are at Nexia Solutions in the UK”

This guy “runs” a post graduate course in the physics and technology of nuclear reactors… I guess this explains a lot about the industry.

I am actually in favor of increasing the use of nuclear fission to provide for our energy needs, provided that it is done right. Unfortunately, I don’t believe that in this country or the UK that has a prayer of happening. It doesn’t have a prayer of being done in this country because flawed economics dictate the direction of the nuclear industry as well as every other industry. The economics are flawed because they do not take into account external costs, such as the real cost of waste disposal or the cost of negative health effects.

The paranoid restrictions on scientific exchange have motivated many scientists to leave this country to pursue a career elsewhere where academic and other freedoms still exist. These restrictions are stupid; even the most primitive countries understand how to make a nuclear weapon.

In light of the worlds pressing energy needs and the demonstration of working superconductive magnetic plasma confinement at China’s EAST reactor, the United States and other member nations should enter into negotiations to accelerate the construction of the ITER fusion reactor.

I also believe we should start work on a second international test reactor project but that it should be of a spherical Tokamak design rather than the conventional design chosen for ITER. The reason for this is that confinement has been shown to be approximately three times better in a spherical Tokamak design of the same size.

A spherical Tokamak presents the possibility of making a reactor that achieves commercial break-even much smaller in size than with a conventional Tokamak designs. This in turn substantially reduces capital expenditures which in turn will make utilities more willing to invest in the technology commercially.

Because ITER is already underway and because ITER will answer important material science questions, I believe it should be completed as is rather than abandoned in favor of a spherical Tokamak reactor.

ITER in it’s current form will take twelve years to complete and then another twelve years of experiments are planned. The amount of money the United States will contribute over the 24 years is equivalent to what we spend on oil imports in two days. This is not the amount we will contribute EACH year, the total amount we are contributing over 24 years is equivalent to what we spend on imported oil in two days.

Controlled hydrogen fusion is the most promising energy source to provide our energy needs in the future. Unlike fission, it produces no significant quantities of long term high level nuclear waste. It has no potential for melt down. And it produces no plutonium or enriched uranium that can be diverted to nuclear weapons or terrorists activities.

Approximately 1/2000 hydrogen atoms in ordinary seawater is deuterium and this is enough deuterium to provide for all of our energy needs for the next 15 billion years. Tritium, which is not significantly present naturally, is also required, however, enough tritium fuel can be bread a lithium blanket and the D-D reactions that do take place to sustain reactor operations in one days operation with just deuterium. So, lacking a tritium supply, a fusion reactor initially powered with just deuterium will take a days operations to become a net energy producer. In reality though this isn’t a problem because we have large quantities of tritium produced for nuclear weapons already and one operational plant can breed tritium for dozens more.

So we should be doing this and we should be doing it as a crash program like Apollo or the Manhattan project, not the current just barely give it enough funding to keep the lights on approach. China built the EAST reactor in nine months. Granted, they had been working on design and component fabrication for years in advance, but it demonstrates how much faster we could move towards bringing fusion online as a power generation source if we were willing to make the commitment.

Lies are being told in order to try to incite a war with Iran. Read about them in the Future Forums.

I have added a link to the sidebar to the Geothermal Power Blog, a comprehensive resource dealing with the subject of geothermal power.

The United States generates only .5% of it’s electricity from Geothermal Energy, and given the widespread existence of generous geothermal resources in the western United States, this is tragic.

However, the rising cost of fossil fuels and improvements in drilling technology have brought the cost of geothermal into the range of being competitive in the electricity generation market. Wind Power exploded and continues to grow after it became economically viable, and I expect we’ll see a similar growth in geothermal energy as a result.

However, I am troubled that we are still building coal fired power plants in spite of the fact that NO fossil fuel creates more carbon dioxide per unit of energy generated than coal. In addition to contributing to global warming, just visit any place where coal is the primary source of electricity. Go outside the town and look up on a cloudless day, the sky isn’t blue, it’s brown. Look at all the buildings in the area, they’ll all have a coat of soot. Look at the people, they all look prematurely aged. Coal burning distributes mercury, and radioactive elements into the environment.

I heard a new coal fired plant is planned for Washington State to be operational by 2014. Given the ample geothermal and wind resources present in this state, this is insanity.

Please folks, click on “Sustainable Future Forum” (button on right sidebar), and share your ideas. Register, it only takes a couple of minutes.

I’ve made this argument before but this photograph demonstrates the need so well. The orange-brown coloring in the sky, I didn’t add that, well I contributed to it since I’m using fossil fuels for energy also, but this is the reason we have to switch to alternatives and stop burning fossil fuels.

That crap in the air, we breath that, and so does every other oxygen breathing organism. It doesn’t stop there, heavy metals present in coal, mercury, radioactive elements, uranium, radium, these things too get dispersed in the air, and we breath them, and they settle out, and get into the food chain. Then we catch a salmon and get an unhealthy dose of mercury. All of our food gradually becomes slightly radioactive.

If we produce our electricity through clean renewable technologies and switched to electric vehicles, then we wouldn’t have that ugly brown cloud hanging over us, we’d have clean clear healthy air.

Chernobyl was the world largest nuclear disaster to date, yet, the people living in the exclusion zone near the reactor actually have better health and lower death rates than their cousins living in major cities. That’s not to say that nuclear radiation is good for you, it is to say that urban pollution is worse!

Up to this point it’s been me here sharing my ideas about how to create a sustainable future so that we can live well and our children can live well and our children’s children. Something that can’t happen if we continue down the path we’re on.

But I’m just one person, just one mind, and there are more than six billion of us on this planet. If we put our minds together we should be able to come up with a lot more solutions than any individual.

So.. I’ve added a new feature, Sustainable Future Forums. Just click on the big button on the right sidebar. It’s new, it’s not very fancy yet, it’s in it’s infancy but with your participation will change. Register, it’s instant and painless, and then you can post.

When president Bush speaks of a hydrogen economy, he is talking about using hydrogen as a fuel. In this context, hydrogen is only an energy storage medium not an energy source. Energy had to be expended separating the hydrogen from water and because efficiencies are never 100%, less will be recovered than expended.

Hydrogen can allow a fixed energy source such as a nuclear power plant to provide energy for mobile applications such as vehicles and do so in a less environmentally harmful manner than fossil fuels and providing the primary source of energy is sustainable, it can do so in a sustainable manner.

Hydrogen can be a source of energy if we can utilize it in a fusion reactor but presently political and economic forces prevent implementation. Deuterium and tritium are the isotopes of hydrogen that are likely to find application in fusion reactors. Tritium doesn’t exist naturally except in trace amounts but could be readily bred by placing a lithium blanket around the reactor. Liquid lithium also has some properties that improve the performance of a fusion reactor.

In terms of hydrogen’s use as an energy storage medium for transportation and other portable applications it has potential with some caveats. Water vapor is a far more effective greenhouse gas than is carbon dioxide, so increasing water vapor content of the atmosphere will increase greenhouse effects however additional clouds will reflect more light, so how that will balance out remains a subject of speculation.

A group of scientists working on alloys for advanced semiconductors discovered that if you drop pellets of an aluminum-gallium alloy into water, it reacts with the water. The oxygen in the water reacts with the aluminum alloy to form aluminum oxide, the hydrogen is released and can be used as a fuel. The gallium is released and can be re-used. Gallium prevents aluminum from quickly developing an oxide layer that prevents significant reaction.

Scientists envisioned this as a way to retrofit gasoline cars to use hydrogen but this would be a poor use of this technology. Spark ignited internal combustion engines have a mechanical efficiency of around 20%. They can achieve up to about 37% at their optimum operating point but only a hybrid vehicle can approach this. Hydrogen is a low octane fuel and requires a reduction in engine compression with a corresponding reduction in thermal efficiency.

Fuel cells have achieved 50% efficiency. Between controller and electric motors, the drive train efficiency is around 85%, so 42% system efficiency can be achieved this way, far better than with an internal combustion engine and the generation of nitrous oxides is avoided.

The recombination of hydrogen and oxygen in a fuel cell is an exothermic reaction and can result in temperatures in the ceramic membranes of 900°C. If this heat is captured and utilized to generate power, significantly higher vehicular system efficiencies are possible. This doesn’t speak to the efficiency of hydrogen generation, around 85% is typically achievable in a commercial electrolyzer.

This means that your electricity to wheel efficiency with a fuel-cell vehicle is going to be around 35%, if hydrogen is burned in an internal combustion engine, only about 17%. In this scheme of aluminum – gallium pellets the actual efficiency in which electricity is converted to hydrogen is not documented but I suspect it’s going to be significantly less.

Consider an all-electric vehicle. A lithium ion battery can return about 80% of the energy used to charge it, that in connection with a 85% efficient drive train can yield an electricity to wheel efficiency of 68%, far better than hydrogen fuel cell vehicle.

For NiMH cells, the charge efficiency can be between about 65 and 98%. A lot of the efficiency with NiMH cells depends on the intelligence of the charger, they are very efficient right up to where they are almost fully charged, then efficiency drops rapidly at high charge rates so a good charger will have a thermal sensor, charge at a high rate until it detects the battery getting warm, then top it off with a trickle charge.

On the discharge curve, a high discharge rate will reduce efficiency, the degree to which this is true varies widely from one manufacturer to the next. For maximum efficiency, choose a cell with good high current discharge characteristics. Consider using an ultracapacitor to spread load spikes. In addition, an all-electric vehicle can use regenerative breaking to recover energy improving the overall efficiency even more.

An all electric vehicle wins hands down in terms of electricity to wheel efficiency over hydrogen fueled vehicles, even those using high end fuel cells. However, if electricity is generated from fossil fuels, even an efficient all electric vehicle will result in an overall fuel to wheel efficiency of only around 31%, and in that case a diesel hybrid will do better. Of coarse what is desirable is to utilize renewable or essentially inexhaustible energy sources to generate the electricity.

By essentially inexhaustible I mean something like controlled hydrogen fusion or properly managed fission generation. There is enough deuterium in the worlds oceans to provide our energy needs for 15 billion years.

Properly managed fission would utilize integral fast reactor facility instead of the one-pass system we have now. Such a system could extract approximately 96% of the energy content of uranium (or thorium) while producing no actinide waste thus eliminating the 50,000 year storage problem, contrasted by our current one-pass system that extracts less than 1% of fuels energy potential and creates waste that will need to be isolated for 50,000-100,000 years.

The high efficiency of such as system would make extraction of uranium from seawater a practical fuel source and would make nuclear power viable for millions of years. It would still produce short-term fission product waste but that represents a much smaller problem than plutonium and other actinides, approximately 300-500 years verses 50,000-100,000 years.

Right now though it happens that wind power is the least expensive means of generating electricity. It also happens that the variability of wind is not such an issue with fuel production as we only have to worry about average production rates and have enough hydrogen storage facilities to bridge the periods where production is inadequate due to slow winds.

Overall though I am skeptical of the hydrogen economy, I think all-electric vehicles will provide the main alternatives to fossil fuel powered vehicles.