The 2006 "Eddington Report" cautioned against the common argument of modal shift from aviation to high-speed rail as a carbon-emissions benefit since only 1.2% of UK carbon emissions are due to domestic commercial aviation, and since rail transport energy efficiency is reduced as speed increases. The 2007 government white paper "Delivering a Sustainable Railway" stated trains that travel at a speed of used 90% more energy than at ; which would result in carbon emissions for a London to Edinburgh journey of approximately per passenger for high-speed rail compared to per passenger for conventional rail; air travel emits per passenger for the same journey. The paper questioned the value for money of high-speed rail as a method of reducing carbon emissions, but noted that with a switch to carbon-free or carbon-neutral electricity production the case becomes much more favourable.