Energy Future Source
It is either the miracle energy source of the future, or the most expensive wild goose chase in the history of science. If it succeeds, it could solve climate change and resource depletion at one stroke. It would be an endless source of cheap power, and our energy-intensive lifestyles could continue with impunity. If it fails, decades of research and billions of dollars will have been wasted. This is the great gamble of nuclear fusion, and since it’s been in the news again this week, I thought it was worth exploring in a little depth.
The limits of nuclear power
Nuclear power is an incredible achievement, and being low-carbon, it is often hailed as an important energy source for the future. However, even putting the expense to one side, there are major drawbacks. The biggest problems are the issue of radioactive waste, and the limited stocks of uranium. At current rates of use, we have around 59 years of uranium left, but that will quickly reduce if nuclear power grows much beyond the 16% of the world’s electricity that it currently provides.
Thorium reactors or ‘breeder reactors’ are much more efficient, but despite decades of development, it is still experimental technology. There is just one fully functioning breeder reactor, the thirty year old and much studied Russian BN-600. A more modern prototype in Japan began transmission in 1994, reported a fire just months later, and has been in repair for 15 years. It came back online in May this year – things move slowly in the world of nuclear power. India has also developed the technology and plans to build a series of ‘second-generation’ reactors that will run off the spent fuel from its conventional nuclear programme. The first of these has been delayed, but is expected to open in 2011.
Despite the potential of breeder reactors, they are subject to the same dangers as any other nuclear reactor, and we don’t yet have a foolproof solution to nuclear waste. Decommissioned power stations are dangerous for decades, and the waste products for thousands of years. Options include burying it in the ground, burying it in deep-sea trenches or, more imaginatively, firing it into space. But some high level radioactive materials have a half life of over a million years – there is simply no safe way of handling something like that, no hole in the ground deep enough or container strong enough.
In the UK we mix nuclear waste into glass, and seal it in steel containers. Eventually, it will be buried deep underground, but we haven’t decided quite where yet. In fact, almost nobody has decided where to put their waste. Russia is stacking it up in the Ural mountains until it finds a safe long-term location for it. The US plan to create a national disposal site under Yucca Mountain has stalled. France has identified a site, but it won’t be ready until 2025, and there have been a series of incidents in the meantime. A proposal to create an international site in the desert in Australia never got off the ground, but it is probably only a matter of time before someone suggests burying it in the desert in a poor and sparsely populated African country.
The promise of nuclear fusion
So what we need is a new generation of nuclear power stations that doesn’t run off a rapidly depleting resource, and that doesn’t produce radioactive waste. And that’s where nuclear fusion comes in. You can run it off the hydrogen isotope deuterium, which is easy to come by – you just extract it from water, meaning you could fuel your power station with the boundless resource of seawater. As for waste, the most harmful by-products such as tritium could be burnt off, leaving some helium emissions and a small amount of solid waste. These solids would be more radioactive, but for a much shorter time – even the most toxic of them would degrade to harmless ash within 300 years.
Nuclear fusion is the counterpart to nuclear fission, the current form of nuclear power. Fission splits atoms to release energy, while fusion bonds them together, creating intense heat. It is the process that takes place inside a star, or the sun. It’s also what happens when you set off a hydrogen bomb. A nuclear fusion power station would fuse hydrogen atoms and generate that intense heat, and then simply use that heat to run steam-driven turbines and create electricity. It’s a beautiful theory.
When you stop and think about it, it gets a little more complicated. You are essentially creating a miniature sun inside the reactor, and while making a sun is one thing, working out what to put it in is another problem altogether. The sun burns under unfathomably enormous pressure, and fuses hydrogen at 15 million degrees. Unable to create that pressure, a fusion reactor would need to push the heat to 100 million degrees to release the energy, and there’s just nothing that can contain anything that hot. “An unearthly kind of fire needs an unearthly kind of furnace,” as Marek Kohn puts it. The solution is really quite astonishing – rather than trying to box it in with exotic composites of metal and ceramic, the reactor contains the charged particles (or plasma) within a magnetic field.
At a recent event in Japan, the developer of this technology, the Brother Industries, showed how the vibration packs were used to power up TV remote control, a remote switch for a lamp and even an LED flashlight. These are perfect devices for the Vibration Energy Cells, because they tend to have low power consumption.
Speaking to the press, the spokesman of the company said that the Vibration Energy Cells could generate electricity using a coil, magnet and condenser that charges electricity. These will all be embedded in the battery. Just by walking with the device in your pocket; it would create enough vibration to power it.
However, we may have to wait a little longer before we start to see the products in the market – as the Vibration Energy Cells are still in trial phase and as of now the company is not planning to bring it to mass market. The two AA-sized prototypes that have been developed can so far generate a voltage of 3.2V – which would be just enough to power your remote controls. But one analyst believes a breakthrough has been made and that the cells have big potential.
Radio Waves
Imagine a device that can harvest all the energy and power they need from ambient radio waves. This can potentially reduce or even eliminate the need for using batteries. Though there are already several people that have been devising such devices, the use of radio waves to power electronic devices remains largely untapped.
