Nuclear power is an energy source but it also has implications for civil liberties such as freedom of speech and assembly. Because nuclear power is centralised, expensive and potentially dangerous, it is a potential target for terrorists. It also increases the risk of nuclear proliferation. Preventing these possibilities means cutting back on civil liberties. The result: nuclear power is not a suitable power source for a free society. Energy systems are concerned with energy, of course, but they also have other implications, for example for the environment and investment policy. One of the important but little-discussed impacts of energy systems is on personal and social freedom. Freedom should be a factor in energy choices. Nuclear power has several characteristic features. First, it is a large-scale energy source: units are typically around 1000MW. A nuclear power plant is very large physically. Second, it is very expensive — it costs billions of dollars to build a single plant.