All That Matters

The crisis at the Fukushima Daiichi nuclear plants is a real tragedy. Tens of thousands of people have been evacuated around the plants, many of which continue to live in shelters with little comfort and privacy. And even worse, there are more than 27,000 people that are either dead or declared missing as a consequence of the earthquake and the tsunami.

The stream of media reporting on the status of the Fukushima plants is continuing, although ironically we are now in a situation where although the continuing release of radiation into the plant’s immediate environment is accumulating to radiation levels that are worryingly high, the broader interest on the issue outside of Japan appears to have ebbed away. And that despite the fact that these problems will be with us for months, if not years.

What is still going strong in the media, however, is the debate on the future of nuclear energy. Some see the accident as a sign that we should stop all nuclear power plants – immediately – whereas others such as George Monbiot see the fact that the implications of this accident so far seem geographically limited as a sign to support nuclear power. Unfortunately, this pro/contra nuclear is where the debate stops, and there appears little movement on either side.

It’s about our energy future

What I am missing in this entire debate is the vision for our energy future. That’s because a sustainable energy supply is a complex issue, where broad brush strokes such as pro or contra nuclear unfortunately don’t help. Take the German government’s decision to shut down seven of its oldest nuclear reactors: unlike the shutdown of nuclear reactors in Japan this hasn’t led to power cuts in Germany. So where does the missing energy come from? This power is bought on the international market. So who can offer spare capacities of around seven gigawatts power or more? My guess is that most likely it’s nuclear energy from elsewhere….

But short-term politics and Fukushima-related knee-jerk reactions aside, how do we envision our energy future? […]

The past year has been a great year for science with major advances in several areas. Too many exciting results to mention here. Instead, to reflect about the past year I have chosen a representative paper for each month of the year that I hope can serve as an example of the great science going on in a number of research fields. Of course, this is a highly subjective and personal collection, and indeed there might be others worth mentioning. But the aim was also to provide a balanced overview of the year that covers a variety of topics.

Of course, if you have an exciting paper to add, please feel free to use the comments section below to let us know!

Anyway, enough said, here are some of my highlights from the past year:

Simulations of electronic excitations in an iron-based superconductor. Image by Oak Ridge National Laboratory via flickr.

JANUARY – iron-based superconductors

Since they were discovered in 2008, iron-based superconductors, the pnictides, have been one of the hottest topics in condensed matter physics. Part of their appeal stems from the fact that they are based on iron, which is a magnetic element. Normally, magnets and superconductivity exclude each other.

The iron-based compounds have a similar crystal structure as the so-called cuprates, which are the materials with the highest superconducting temperatures known. The mechanism for these high-temperature superconductors is unknown, and studying the iron-based superconductors may also be relevant to the understanding of the cuprates.

This paper published in Science shows for the first time that the electrons in the iron-based superconductors show a periodic arrangement that is different to the periodicity of the atoms in the crystal. Similar observations have been made in the cuprates, and their understanding is considered important to the mechanism of high-temperature superconductivity.

Chuang, T., Allan, M., Lee, J., Xie, Y., Ni, N., Bud’ko, S., Boebinger, G., Canfield, P., & Davis, J. (2010). Nematic Electronic Structure in the “Parent” State of the Iron-Based Superconductor Ca(Fe1-xCox)2As2 Science, 327 (5962), 181-184 DOI: 10.1126/science.1181083

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Rechargeable batteries. In comparison to lithium-ion batteries these are an older but more cheaper technology generation, made from metal hydrates. Image by comedy_nose via flickr.

The title of this blog post is a bit tongue in cheek, but the situation isn’t that far from the truth when it comes to rechargeable batteries such as lithium-ion batteries. Ever since lithium-ion batteries were first commercialized in 1991 by Sony, based on work by John Goodenough and others, they have been highly successful in the market. Open your mobile phone and read the battery label, almost certainly it is a lithium battery. The lithium stores electrical charges in the battery’s anode. During discharge of the battery the lithium moves to the cathode, where the charge is released. Lithium-ion batteries are also used in electric cars, in laptops, for electric power tools and so on. The market is huge.

On the other hand, if you use these rechargeable batteries, their real-world problems are pretty clear. Storage capacity could be better, particularly for electrical cars. Then, these batteries should be rechargeable more often without degrading, and last but not least the charge cycle should be reasonably fast.

The success of lithium iron phosphate

The bottleneck in the storage capacity of lithium-ion batteries is how much lithium the electrodes can take up. In particular the cathodes are a problem, their capacity is smaller than that of the graphite anodes used. One of the best cathode materials, proposed by Goodenough early on, is lithium iron phosphate (LiFePO₄). Unfortunately, lithium iron phosphate as studied by Goodenough didn’t work well, it didn’t conduct electrical current! In 2002, Yet-Ming Chiang and colleagues from MIT then published a paper where they fabricated lithium iron phosphate that is made conducting through the addition of other metals. Furthermore, Chiang also discovered that if nanoparticles are used instead of bulk to make the cathode, the surface area of the electrodes is increased and hence their efficiency goes up.

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