Subscriber Chris sent us an email earlier this week inquiring about heavy water. We thought it was a topic that might interest a lot of water folks, so here it is in today’s blog. As it is used in nuclear energy, the Dire Straits tune “Heavy Fuel” came to mind.
We all know that the chemical formula for water is H2O. That tells us that the water molecule is composed of two Hydrogen atoms each attached to a central Oxygen atom. We think of each atom of an element as being identical, and this is generally true: each Hydrogen atom has a single proton in its nucleus, making it the simplest of all known substances. Oxygen has eight such protons.
A proton has a positive electrical charge, but atoms have no such charge. To accomplish this, there has to be one negative charge — an electron — for each positively charged proton in an atom. So every atom has the same number of protons and electrons, and every atom of a single element has a unique number of these. This is known as the Atomic Number, and it is 1 for Hydrogen and 8 for Oxygen.
Protons outweigh electrons by a factor of about 2000, so the electron’s contribution to the mass or weight of an atom is pretty small. But there is a third component to the atom that weighs almost exactly the same as a proton: the neutron. And, as the name implies, the neutron has no electrical charge. That means that an atom can have any number of neutrons and still remain neutral in electrical charge.
Atoms of a single element MUST have the same number of protons, but they MAY possess varying numbers of neutrons. This changes the mass or weight of each atom. These atomic “cousins” are called isotopes — atoms of the same element that possess different masses.
The most common isotope of Hydrogen has no neutrons, and is called Protium. “Heavy” Hydrogen has one neutron as well, doubling the atom’s mass. This isotope is called Deuterium. There is another isotope of Hydrogen called Tritium, which has two neutrons. However, the heavy water is formed when at least one of the two Hydrogen atoms is the Deuterium isotope.
Deuterium has been used in nuclear power and weaponry since the early 1930’s, and was one of the main reasons that Nazi Germany invaded Norway: the Norwegians were producing heavy water.
We are true believers in a future on Earth with cheap, clean, and limitless energy. And we’re not talking about windmills or solar panels. Our energy future lies in nuclear fusion. And one of the most promising fuels for this form of energy is Deuterium. It is estimated that the Deuterium in a cubic mile of seawater — and Planet Earth has many, many cubic miles of seawater! — would produce as much energy as all the known petroleum on the planet.
So heavy water is potentially heavy, heavy fuel!