At the end of the non-technical portion of his book, David MacKay estimates what it would take to renewably power the United Kingdom, switching forever away from unsustainable fossil fuels. With one possible approach, he reckons that it would require the following:
- 52 onshore wind farms: 5200 km2
- 29 offshore wind farms: 2900 km2
- Pumped storage: 15 facilities similar to Dinorwig
- Photovoltaic farms: 1000 km2
- Solar hot water panels: 1 m2 of roof-mounted panel per person. (60 km2 total)
- Waste incinerators: 100 new 30 MW incinerators
- Heat pumps: 210 GW of thermal energy pumped
- Wave farms â€“ 2500 Pelamis, 130 km of sea
- Severn barrage: 550 km2
- Tidal lagoons: 800 km2
- Tidal stream: 15 000 turbines â€“ 2000 km2
- Nuclear power: 40 stations
- Clean coal: 8 GW
- Concentrating solar power in deserts: 2700 km2
- Land in Europe for 1600 km of HVDC power lines: 1200 km2
- 2000 km of HVDC power lines
- Biofuels: 30 000 km2
- Wood/Miscanthus: 31 000 km2
In total, this adds up to about 300 gigawatts (GW) of energy for transport, heating, buildings, and everything else. What this suggests is that, if you want to maintain population density at levels similar to now along with per capita energy use, you need to turn entire densely populated countries into energy factories even with nuclear and ‘clean coal.’ While he doesn’t estimate costs for the last two, his ballpark estimate for building all the rest are about Â£870 billion. That number may well be an overestimate, since the costs for many of the technologies are extrapolated from a few pilot facilities.
That may seem like a staggering amount of money and land. On the money side, however, it must be borne in mind that the UK is currently spending Â£75 billion per year on imported energy. That means the whole conversion would cost as much as about twelve years of continued fossil fuel use, at prices similar to now. The land use change may be a far bigger barrier. Making the UK into a renewably-powered country requires devoting a considerable portion of its total land area to that purpose. That’s a lot of spoiled views and local resistance to overcome.
He offers five other energy plans for the UK, based on different balances of technology. He also has energy plans for Europe, North America, and the world as a whole. To make the figures add up, they all require either nuclear, massive solar farms in the desert (600 by 600km), or both.
Countries are going to need to make some hard choices about population size, energy use, and the maintenance of land for agriculture, wildlife, and human enjoyment.