New Ideas and New Products

I read an article today which mentioned that the naturalist Sir David Attenborough has become patron of the Optimum Population Trust, a think tank campaigning for global research and awareness of the issue of population growth and the effect it is having on planet earth.

According to the United Nations the global population is expected to grow from 6.8 billion today to 9.1 billion in 2050. Here are a few of the OPT’s conclusions:

• Water demand exceeds supply in nearly half the world’s countries: by 2025 two-thirds of the Earth’s population will live in water-stressed areas.
• The proportion of cultivated land on the planet has increased from 7% to 40% in 300 years, with almost no room left for expansion.
• Oil and natural gas look set to ‘peak’ within a decade or two and it’s doubtful that either nuclear or renewables can fill the gap. (I agree with the first half of that statement but disagree with the second half. I believe solar power has the potential to be an extremely cheap and abundant form of energy in 10-15 years. Although Nuclear Fusion power has its issues as I discussed here recently, I believe it could be a potential solution in the more distant future.)
• If we believe climate change has anthropogenic origins then population growth is not going to help.
• Population is growing at 1 million people every 5 days.
• Humanity is currently using 120-140% of the resources that the Earth can sustainably provide.
• This topic has become too controversial an issue for politicians and environmental groups to address for fear of causing offence. It can sound anti-people, and pro-poverty.
• This isn’t just an issue for the developing world. People in the developed world consume far more resources and emit more pollution than those from the developing world.
• Ultimately the world needs to reduce its population by about half to around 2-3 billion.

Some rather sobering conclusions but I believe they come from solid academic study. How we start to address this problem I do not know. Maybe Obama should wait for his second term to address this issue!

So what is the situation with nuclear fusion? Are we close to being able to use nuclear fusion as an electricity generating source?

After the invention of the nuclear fission bomb back in the 1940’s scientists were able to find a way of using the energy released from splitting atoms to generate electricity within about 10 years. However, it is now around 50 years since the Hydrogen bomb was invented so why haven’t we been able to convert this into a feasible source of electricity generation?

As an idea electricity generated from nuclear fusion is perfect. It is a clean source of energy (unlike coal, natural gas or crude oil), it uses Hydrogen as fuel (the most abundant element on earth), it requires tiny amounts of the fuel, it produces no radioactive waste (unlike nuclear fission that uses Uranium), it can provide baseload power (unlike wind or solar) and it does not rely on the weather (unlike solar, wind and hydro power).

There a number of problems with nuclear fusion with current technology.

1. We end up putting in more energy than we get out.
2. The length of time between actual fusion events is too long, i.e. in the order of hours rather than minutes or seconds.

However, technology is improving. Whereas say 15-20 years ago experiments were inputting say 30 times more energy than they were extracting, a project in Korea now expects to be about 1 to 1. So why do we have this problem of not being able to extract more energy than we put in?

This really relates to the amount of energy we need in order to force the two atoms together. But first…

A quick explanation of Nuclear Fusion:

Nuclear Fusion is the forcing together of two atoms to create a new heavier atom. When you force two light atoms close enough together they will combine together to make a heavier atom and also release energy.  The fuel that tends to be used is Deuterium which is a special type of naturally occurring Hydrogen which is made up of one proton, one neutron and one electron. These are forced together to eventually produce the inert gas Helium.

So why do we get energy out when we combine two light atoms together to form a larger one? Well this is explained by Einstein’s famous equation E=mc^2. What this equation is saying is that energy and mass are essentially the same thing. Or in other words mass can be converted into energy. So what we find is that when we bring two light atoms together the resulting larger atom does not have the same mass as the sum of the two lighter atoms. It actually has less mass and the mass that no longer exists has been converted to energy.

The problem is that in order for us to force these two small atoms together they have to overcome an enormous electrostatic repulsive force which is the same force you experience when you try forcing the north pole of two magnets together. This force is far stronger than the gravitational attraction of the two atoms. If we can get the two atoms close enough together then another force known as the “Strong Force” overcomes the electrostatic force and the two atoms combine and fusion occurs. Therefore we have to put in large amounts of energy to get fusion to occur.

In a huge body like the sun the energy released by the fusion of one set of hydrogen atoms contributes to another set and so on and therefore it is self sustaining. However, on earth we have to use only a small amount of material so that we can initiate fusion and also contain the energy that it gives off, if we failed to contain it we would have an almighty explosion.

This means that the fusion events that have been created in experiments only last a short time. For example the Joint European Torus were able to create an output of 10MW but for only half  a second. The experiment then has to be setup again which can take hours.

One new project called ITER in France which is currently under construction hope to be able to produce a net energy output for a meaningful length of time. However, this is still probably 20 years away and even then it is only an experiment.

It doesn’t look like we are going to see electricity flowing into our grids from nuclear fusion in the near future. However, i think it is really important to continue to explore fusion as a source of electricity because it has the potential to provide cheap, clean baseload power. The IEA expect energy demand to increase 50% by 2030 due largely to a demographic shift towards the middle class in developing countries such as China and India. We clearly can’t rely on coal and natural gas due to depleting reserves and the effect it is having the climate. And as much as I support the use of wind and solar and other forms of alternative energy what we really need is a baseload source of power. At the moment the only other alternative is nuclear fission which I think we will have to rely on until we can find a way of making nuclear fusion work for us.