I recently finished reading "A Piece of the Sun: The Quest for Fusion Energy" by Daniel Clery. In the book, Clery summarizes how the fusion research endeavor began and how each individual or group contributed to it over time, concluding around 2012. It covers most of what needs to be said on the subject.
The obvious use for fusion energy is to provide electrical power for cities, or generally on a larger scale. Currently, progressive fusion research requires international collaboration, extremely rare materials, and delicate parts in gigantic machines to produce less than effective results.
I have always dreamed of utilizing fusion
batteries to power various things, from heating and cooling,
to propulsion, and especially supercomputing.
My idea is unique in that the fusion device is small. Household items could be engineered to utilize its own individual power source, instead of requiring a plug. In turn, this would completely decentralize power needs. Extremely large power stations would become obsolete, buildings would no longer need extensive wiring to provide electricity to lights, computers, and other systems, and unsightly power lines could be dismantled. At the very minimum, the battery should be small and safe enough to be easily introduced into a typical home, and potent enough to run all its devices simultaneously. The only downside is, like all batteries, it would need to be disposed of properly, and then replaced at predictable intervals.
Problem: Substantial magnetic fields are required to keep the plasma from touching any solid surfaces so it doesn't damage the device or its surroundings. This is especially the case if these batteries becomes a consumer product.
Problem: Even when regulated, such a device could easily be turned into a weapon.
Solution: Completely seal the container with the electromagnets needed to sustain the plasma. The electromagnet container would be encased in a solid metallic or composite shell. Any tampering or attempt to open the shell would break a vacuum or release an inert gas, oxidize the electrical wiring, and freeze the battery. Since the device is filled with hydrogen surrounded by some electromagnets, the most dubious re-purposing would result in a 6th grade science project.
Problem: The nature of physics, especially plasma physics. Electromagnets are not typically small devices. Even when they are, they are not necessarily intended to be used for plasma containment. Plasma physics seems to be leaning more towards the cosmic scale when put in context with energy production. In other words, in order to produce electricity from fusion, the larger the device, the better. Smaller machines do not have the proportions necessary for certain reactions to occur, or to sustain a fusion state for any substantial period of time.
Plasma also behaves in ways that are unpredictable due to fact that it typically doesn't exist except for at temperatures that would more or less kill us if we were in direct contact with it. We can interact directly with solids, liquids, and gases. Indeed, we do so daily. There are some that are less common that are more difficult to handle, such as liquid nitrogen or helium, solid argon, or chlorine gas. Plasma cannot be handled at all, though, because it is the state beyond solid, liquid, or gas. You have to provide a material with enough energy to ionize it, which on Earth, is a very difficult process. Ionization, in this case, requires electricity, and currently, we only have electricity because of coal, oil, natural gas, tidal forces, steam, solar cells, and the wind. We have been very clever to come up with this many ways to produce electricity, and that clever ingenuity only comes from a dire necessity originating from a heightened standard of living. You know, like microwave ovens.
Solution: The solution making a fusion device lies with the fuel used to initiate the plasma. The ideal fuel is hydrogen. Not heavier types of hydrogen. The common type. Using the "protium" isotope means no shortage of fuel. Ever.
Problem: Inducing enough ionizing energy into the hydrogen to make it form plasma and ignite fusion.
Solution: Initiating fusion at the production facility. If the fusion reaction is truly producing electricity, then the reaction is also self-sustaining, and only requires a focused electrical-based force (like a laser) once in its lifetime . Returning to the earlier point that plasma physics tends to be more cosmic in nature, the bigger the battery, the longer it would last. This fusion battery would only last a few years at most, and that's thinking ideally.
Problem: Fusion doesn't necessarily create electricity like some think it automatically does.
Solution: The battery would have to either be made of a composite material which charges conductive materials, or to heat water into steam which then transfers its kinetic energy into electricity by rotating a turbine. That stipulation on its own creates a device larger than a washing machine, if not much, much larger.
Fusion batteries rely on a few technologies being figured out and made commercially available: plasma containment on a small scale - small efficient electromagnets; hydrogen fusion ignition - NOT deuterium or tritium; composites that can transform heat into electrical energy (like RTGs only without the radioactivity); and nano mechanics - if you're going to produce electrical energy in a small device, you either don't use moving parts (no steam), or you use steam and need tiny moving parts.
Even if the fusion battery is just a tiny steam turbine, that's still better than burning coal or methane to keep warm and keep our lights on.
On a side note, if it took 1 zettawatt of electrical power over 1 year to ignite enough fusion batteries to last all of humanity just 1 more year, we would still be 126 times more efficient at producing power than we are as of 2008.
And those batteries could be used to create more batteries, limited
only by the materials that each battery is made of, and the physical
space they consume.