Book Review: Sustainable Energy -– Without the Hot Air, by David JC MacKay

I recently finished reading  a book I strongly recommend to anyone interested in sustainable development and energy. It is packed with figures and findings that I believe will easily start discussions among CleanTechies.

The author, David JC MacKay, is Professor in the Department of Physics at Cambridge University and was recently appointed Chief Scientific Advisor to the UK Department of Energy and Climate Change responsible for the Low Carbon Transition Plan.

One of the main findings of this book is that electrifying our cars and installing heat pumps in our buildings would enable us to cut significantly both our greenhouse gas emissions and fossil fuel consumption. Both solutions are much more efficient than the current traditional ones and could benefit from massive electrification to answer all our energy needs.

Below is a selection of the book’s key findings:

Sustainable Electricity: MacKay believes that the UK and Europe in general can’t count solely on renewables. He shows that wind, biofuels, hydro, solar PV and other energy sources don’t add up enough energy to answer our current needs and will do so to an even lesser extent in the future, once we have a strong electrified transport sector.

So we need a plan that provides additional resources, for example concentrated solar (like the Desertec project), or nuclear, or a combination of both. Clean coal may also add up enough electricity if proven viable.

North American Energy Consumption: The author notes that the continent should first and foremost decrease energy consumption from 250 kWh per person per day to the current European or Japanese levels of 125 kWh. This could enable the continent to rely solely on renewables with the installation of concentrated solar in its deserts.

European Energy Consumption: With Europeans consuming the equivalent of 125 kWh per day per person, we see a breakdown of transport accounting for 40 kWh per day, and heating for another 40 kWh. Delivered electricity amounts to 18 kWh but due to the inefficiencies of the system, this comes from 45 kWh of energy. With improved efficiency, we could go from the current 125 to around 80 kWh, a figure similar to that of Hong Kong. (This simplification for the sake of the argument doesn’t take into certain factors that are are tackled in detail in the book.)

Future Scenarios: In chapter 27, the author gives five examples for plans that add up enough electricity. The baseline plan is as follow: Clean coal 16 kWh per day per person, nuclear 16, tide and wave 5.7, hydro 0.1, waste 1.1, pumped heat 12, wood 5, solar thermal 1, biofuels 2, solar PV 3 and wind 8. The four other plans give more or less importance to each of these energy sources. In one plan, nuclear accounts for 44 kWh when in another plan, wind energy accounts for 32 kWh.

Transportation: Today, electric cars need as little as 15 kWh for 100 kilometers while models running on oil need 70 to 90 kWh. Hence, electric cars are already five times more efficient than current conventional models. (Side note: SUVs – also called spaceships by the author – need around 120 kWh…) High speed rail and other sustainable alternatives also have to be pushed forward. A full high speed train only consumes as little as 3 kWh per passenger, and biking consumes even less: 1 kWh.

Housing and buildings: The author is an advocate of both retrofitting and reducing the winter thermostat from 20°C to 17°C, which alone brings savings of 30% (page 292). By combining both solutions, David MacKay halved his heating bills. With a coefficient of performance (COP) of 4 to 5, heat pumps retrieve the heat contained in the outside air or soil and distribute it indoors. Another advantage of this solution is that it can bring air conditioning during hotter days.

The book is available for free on the official website. You can download it in one document or read it per chapter. The paper version can be bought for around $32 / €22. Published this year, it is up to date and explains simply but most effectively (and with a good sense of humor) how we can create a low carbon energy economy.

Grade : 20/20. A must read.

Readability: Maximum as it brings a lot of data.

Further information: MacKay in a recent article on the BBC – most interesting.