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Last month Italian inventor Andrea Rossi was granted a U.S. patent for a fluid heater. At first glance, that’s not a particularly gripping opening sentence for a lively or interesting science column. But there is more to the story, a lot more. First off, the heat source in Rossi’s invention is purported to cold fusion. If Rossi really has mastered cold fusion, the world is about to become a very different place. There is also a local angle. Rossi is a partner in the Raleigh-based Industrial Heat, LLC who have been operating one of the patented fluid heaters at an undisclosed location for the last six months.

There are several aspects of this story that intrigue me, so I’ve laid out a three-part exploration. This week I’ll cover the science of cold fusion. Next week I’ll discuss the history of efforts to achieve cold fusion and then conclude the following week with the potentially world-changing implications. So on to the science.

Let’s start with a definition of cold fusion. Cold fusion is the generation of energy from the fusion of atomic nuclei at “reasonably” low temperatures. To me, reasonably low would be anything below 1,500 °F since this would allow us to use known types of industrial equipment. Given that nuclear fusion, the process that powers the sun, generally occurs at tens of millions of degrees, 1,500 °F still qualifies as cold.

nucleus

As you can see from the picture above, atomic nuclei are composed of positively-charged protons and neutrally-charged neutrons. The number of protons in the nucleus determines identity of the atom. For example, hydrogen atoms have one proton, helium atoms have two protons, and nickel atoms, which will be important later in this story, have 28 protons.  Atoms also have electrons, but they are not relevant to our story.  If a nucleus contained only protons, the repulsive forces between the protons would cause it to break apart. The neutrons function as spacers to prevent that from happening.   Please note that hydrogen, since it only has one proton, is the exception to this rule.

A confusing but extremely important characteristic of nuclei is that the same type of atom can have different numbers of neutrons. For example, all nickel atoms have 26 protons, but some have 32 neutrons, some have 34, and some 36. These different forms of nickel are called isotopes and are referred to by the sum total of the protons and neutrons in the nucleus. Therefore, a nickel atom with 26 protons and 32 neutrons is called nickel-58, one with 26 protons and 34 neutrons is nickel-60, and one with 26 protons and 36 neutrons is nickel-62. Generally speaking the nuclei of isotopes with more neutrons are more stable since they keep the protons spaced farther apart. All atoms, including hydrogen and helium, have more than one isotope. These isotopes of hydrogen and helium are going to central to our story in Parts II and III of this series.

With the review of atomic structure and nomenclature behind us, let’s move on to nuclear energy. We can generate energy either by breaking large nuclei into smaller ones (nuclear fission) or combining small nuclei into larger ones (nuclear fusion).

Fission is the approach used in atomic bombs and nuclear power plants. In this process you start with an unstable isotope of a large atom such as uranium. Next you shoot a neutron at it. This causes the uranium nucleus to break apart into two smaller nuclei and also to releases two or more high energy neutrons which can go on to break more uranium nuclei. Breaking the uranium nucleus also releases energy. To make sure that was clear, please look at picture below.

fission

We need to pause at the point and discuss the energy released in fission. If you start with a uranium atom and then shatter it, the sum of the masses of the smaller pieces will add up to less than the mass of uranium atom you started with. There is a lengthy quantum mechanical explanation for this loss of mass that I will not attempt to cover. What we need to focus on here is that this lost mass is what is referred to by the “m” of Albert Einstein’s famous equation, E = mc2.   If we take the amount of mass loss in our fission and multiply it by the speed of light squared (that’s the “c”), we can calculate how much energy is released. It’s a lot! Therefore, if you start a fission process with uranium and let it proceed unchecked the amount of energy released boggles the mind. This how and atom bomb works.

In a nuclear power plant, the rate of fission is kept at a manageable rate with the use of control rods that can absorb some of the neutrons before they break another uranium atom. So allow the term is not generally used, it can be said that in the form a nuclear power plant, we have achieved “cold fission.” The heat from the controlled fission is then used to make steam. If you want to know how steam is used to produce electricity please read Electricity Production 101. The Achilles’ Heel of nuclear power using fission is that spent fuel remains dangerously radioactive for millions of years and, despite running the power plants for many decades, we have yet to come up with a plan for its safe disposal.

In nuclear fusion, energy is produced when you cause two nuclei to fuse into a larger one. We’ll get into more detail in part two, but below the equation for the simplest possible nuclear fusion. (Keep in mind for next week that which isotopes of hydrogen are used is important.)

H + H –> He + energy

In this process, the helium atom has a mass of just a bit less than the two hydrogen atoms from which it was made. Here again the amount of energy release can be calculated from E = mc2.

The fundamental challenge of fusion is that nuclei, since they are positively charged, repel strongly one another. Therefore, you have to apply tremendous pressure at a temperature of tens of millions of degrees to force them to fuse. That works just fine in a star or hydrogen bomb but is not too practical for your local power plant.

Cold fusion, if we could master it, has dramatic advantages over both cold fission and all other known energy production methods. Below is a partial list.

  • The hydrogen needed for fuel can easily and cheaply be obtained from seawater. So the supply is effectively infinite where as uranium becoming increasingly scarce.
  • You don’t end up with a pile of radioactive waste to store.
  • No greenhouse gases are released.
  • Unlike coal, or natural gas, or petroleum, or uranium, there are no mining or drilling operations.
  • It’s estimated that the energy from cold fusion would be 100 times less expensive to make than that produced from coal or natural gas.

Part III of this series will explore the implications of these advantages in detail.

I’ll pick up the story next week with a review of the efforts to achieve cold fusion over the last 100 years and explain why I think that Rossi’s invention may have an important flaw.

Jeff Danner talked cold fusion with Aaron Keck on WCHL Monday.

 

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