Common European toroid reactor – 700 megawatt input power
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By Steven B. Krivit
October 5, 2021
Most of the people I speak with who are first discovering the power differences with fusion reactors are at first incredulous. They can’t believe the Joint European Torus (JET) fusion reactor needed 700 megawatts of electricity to run instead of 24 megawatts. They cannot believe that the International Thermonuclear Experimental Reactor (ITER) will require at least 300 megawatts of electricity to operate instead of just 50 megawatts.
They cannot believe that the SPARC reactor planned by the Massachusetts Institute of Technology / Commonwealth Fusion Systems partnership is not designed to produce net power.
Some journalists – and favorite television physicist Michio Kaku – have even been led to believe that the National Ignition Facility produces fusion reactions that release 70% of the energy consumed by the device.
One of the most common questions people ask me is how I discovered this trail of deception. It was an accident. I ran into it. Here is an excerpt from my 2016 book Fiasco fusion, which explains the story.
Thermonuclear fusion 50 years later
Since the 1970s, researchers and advocates of thermonuclear fusion have said that practical fusion reactors are only two decades away.
Ethan Siegel, Professor of Physics and Astronomy at Lewis & Clark College, Ph.D. in astrophysics, wrote on the progress of fusion on the Forbes.com blog on August 27, 2015: “The reality is that we are getting closer and closer to… breaking even. [power] point in nuclear fusion – where we get out so much [power] as we put it. Yet there is still no practical fusion reactor, and no experimental reactor has produced a single watt more than the total power required to run the reactor.
As I checked out the basic facts about the constant technical advancements claimed in fusion research – which I had assumed to be correct – I discovered an astonishing gap between what was reported publicly and the actual advancements in potency. net produced by the merger.
Representation of net power
One of my technical writers [Mat Nieuwenhoven] asked if I had any information on the progress made in increasing net fusion power over the decades.
I emailed Stephen O. Dean, the director of Fusion Power Associates, a nonprofit research and education foundation, and asked if he had any such information. He did not do it. Slowly, the image became clear. I quickly learned how important the expression of the initiates “injected power” or “heating power” or “applied fusion power” was important.
“Applied fusion power,” Dean wrote, “is not a relevant measure of progress as these are all experiments not designed for the net. [power]. The input referred to is only the plasma input and does not include the power required to operate the equipment.
I was confused. I thought the numbers – for example, the 65 percent quoted for JET – reflected total net power. I asked him if he knew the best total net power for these devices. He did not do it. I asked him if this meant that the peaks of the JET and TFTR were based on input heating power rather than total input electrical power. Yes he did, he wrote. Now I was worried.
As I soon learned, in addition to the power required to heat the plasma, power is consumed in tokamaks by a variety of processes. The most important of these is the power required to create and maintain the magnetic field which suspends the plasma in the toroidal chamber.
Two accounting methods
At first, I didn’t think fusion researchers normally represented only a fraction of the total input power when they reported net power values. I called [Michel Shaffer] a plasma fusion physicist who worked for General Atomics and asked him to explain this. He corroborated what Dean told me. It was true.
Yes, people in the magnetic fusion research industry, since the 1970s, have always used applied heating power rather than total system input power to report their progress. I asked [Shaffer] if it knew how much the actual total input power to the system was greater than the input power to the heater. He guessed that, generally, the total input power was about 10 times that. If this was correct, then the merger results had been exaggerated by an order of magnitude for decades.
I sent a request to Nick Holloway, the media manager of the communications group at the Culham Center for Fusion Energy, which operates the Joint European Torus. I told him that I understood that JET generated 16MW fusion power with 24MW applied heating power. I asked him if he could tell me how much total input electrical energy was needed to produce so much energy.
“We unfortunately don’t have the power supply figure for this pulse at hand,” Holloway wrote. “Below is some information from my colleague Chris D. Warrick on typical JET electrical power levels, so it will be around that. But if you need the exact input figure, we can figure it out. Here is Warrick’s email:
The general answer is that a JET pulse typically requires around 700 MW of electrical energy to operate. The vast majority is used to power the copper magnetic coils and the rest in the subsystems and to power the heating systems. In future machines, the copper coils will be replaced by superconducting coils, which will ensure that the total input power is significantly reduced. I do not have in hand the specific figures for this particular impulse.
Order of magnitude difference
Holloway and Warrick had confirmed this: the total input power was an order of magnitude greater than the applied heating power, as was the value that was universally used to represent the state of the art in research. on thermonuclear fusion.
The total system input power used for the JET world record fusion experiment was approximately 700 MW. So, a more accurate summary of the most successful thermonuclear fusion experiment is as follows:
With a total input power of ~ 700 MW, JET produced 16 MW of fusion power, resulting in a net consumption of ~ 684 MW of power, for a duration of 100 milliseconds. In other words, the JET tokamak consumed ~ 98% of the total power given to it. The “fusion power” it produced, as heat, was about 2% of the total power absorbed.
As most people would understand the term “fusion power,” JET produced none. (This calculation assumes, as an example, that the number of ~ 700 MW is an accurate value with three significant digits, which it probably is not.)
The truth about the overall efficiency of reactors has been so well hidden that even Charles Seife, the author of a pessimistic book on fusion, has missed it. He, too, did not know that the researchers were reporting their absorbed power as a function of the thermal power applied rather than the total electrical power. Seife believed that the best JET experience lost between 10-40% of the input power.
JET put out 6 watts for every 10 it put in. It was a record and a remarkable achievement, but a net loss of 40 percent of [power] is not the mark of a great powerhouse. Scientists would claim – after manipulating the definition of [power] put into the system – that the loss was only 10%. Maybe it was, but it still wasn’t breaking even; JET was losing energy, not succeeding.
Seife had no idea that JET had lost around 98% of the entry [power], rather than 10 to 40% of the input [power]. The shorthand generally used to describe energy production in the fusion community has created a mistaken view of its success among most observers.
This is the end of the excerpt from my book.
I had already consulted Google. But by the time Holloway sent me the value of 700 MW, on December 1, 2014, I had not found any books or web pages that cited a value for the overall input power required for the JET. It was only after learning the input value of Holloway that I was able to put this number into my search criteria and locate a published reference for it.
A copy of the email I received from Holloway can be found on this webpage, along with any sources I found for ITER’s input power requirements.
Once I understood how fusion scientists had communicated the JET results almost universally, I realized that they had done the same with the projected power values for ITER. And I later saw scientists from the Massachusetts Institute of Technology / Commonwealth Fusion Systems do it too.
Coming back to Nieuwenhoven’s question about the advancements in reactor power output over the decades, I produced a detailed report titled “When will we have energy from nuclear fusion?” Which answers this question.