Professor David MacKay and the Renewables Delusion

“I’m not pro-nuclear- just pro-arithmetic”.

The cause for a rational evidence-based approach to energy policy has suffered a huge loss with the death of Professor David Mackay  three weeks ago, on April 14th.

Mackay, Chief Scientific Advisor at the UK government’s Department of Energy and Climate Change, was the author of Sustainable Energy Without Hot Air, a key text that has been my number one stop to point folks to as a starting point for understanding energy supply and demand. In particular, I have frequently cited this table which explains very well the limitations of wind and solar energy due to their relatively low energy density:

Power per unit land or water area

Based on these figures, population and current energy demand, MacKay calculates that Britain cannot live on its own renewables- they simply need too much land.

By contrast to the 2-20W/m2 that can be achieved through wind or solar pv power, fossil fuels or nuclear power are extremely energy dense, perhaps delivering up to 1000W/m2- or 1-2 orders of magnitude greater.

Additionally, wind and solar are intermittent in that they only supply energy when the wind is blowing or the sun is shining, and so would need a baseload back-up- typically natural gas- or a whole additional infrastructure of energy storage would be required, which is very expensive and the technology does not yet exist to do this at scale.

A third factor, which is a result of the first two, is the speed at which renewables can be deployed.

If decarbonisation is the goal, France decarbonised most of its electricity supply using nuclear power 6 times faster in the 1980s than the famous German Energiewende is achieving today:


In MacKay’s last interview given to Mark Lynas shortly before his death (below), he is very outspoken about the lack of energy literacy applied to energy policy, leading to dangerous delusions:

there’s so much delusion, it’s so dangerous for humanity that people allow themselves to have such delusions, that they are willing to not think carefully about the numbers, and the reality of the laws of physics and the reality of engineering….humanity does need to pay attention to arithmetic ad the laws of physics.

He goes on to lament the emergence of a new delusion- that the  drop in price of solar and wind in recent years signifies a greater capacity for them to replace fossil fuels- but calculates that price would have to come down by a factor of 100 to make much difference (for battery storage also)- and even if they were free, they would still be just as costly in terms of land-use. Dream on…

Solar and wind can still play a role perhaps, in sunnier parts of the world, but is likely to remain relatively small. Although fossil fuels have dropped slightly in terms of their total share of supply to the UK, they still supply 85% of our power.

Meanwhile, in Germany they are also busy closing the largest supplier of low-carbon energy they have, and one would be forgiven in thinking that the decarbonisation agenda is really just a smoke-screen to facilitate the  traditional Green anti-nuclear agenda.

To replace fossil fuels, the only option is to move forward to a more energy dense fuel, not one that is 100 times more diffuse and intermittent to boot. Based on arithmetic, rather than ideology, in the foreseeable future that can only mean nuclear power.

If you are interested in honouring the legacy of David MacKay and would like to include arithmetic and basic engineering to promote a realistic energy policy, you can do worse than to start with reading his book, or if you prefer, watching his talk from 2010: