Sustainable Energy - without the hot air

A crystal-clear and quantitative view of the road towards a low-carbon economy

The book Sustainable Energy – Without the Hot Air by David J.C. MacKay is a unique case among all of the current publications on this topic. If every author and decision maker involved with climate change and energy issues would take this book as a starting point before making any claims or proposals, the world would be saved a huge amount of discussion-energy, energy-to-disentangle-confusion, and energy-spent-on-fruitless-efforts.

'What exactly do you mean by "a huge amount"?' David MacKay would ask me at this point. Indeed, one of the remarkable facts about his book is that it is free of meaningless claims. In his introduction, he cites that most publications on sustainable energy do not give numbers or examples that are easily compared or put into perspective. What they do give are data used simply to impress.

MacKay’s book, on the other hand, constructs several numeric examples on how to create a low carbon economy in the UK. He reduces all figures to the unit of kWh per person per day, making the problem suddenly very transparent.

Facing the numbers

The first part of the book is called 'Numbers, not adjectives'. It builds up a red stack enumerating the energy cost of the main energy-consuming activities within the UK, and a green stack adding up all potential renewable resources available in the UK. Out of this exercise comes the first main conclusion: 'If economic and public objections are set aside, it would be possible for the current average energy consumption of 125 kWh per person per day to be provided from domestic UK renewable sources'. However, the financial cost and the impact on the British and Northern Ireland countryside and seaside would be so immense, that it is very unlikable that the public would ever accept such an extreme arrangement. Consequently, an energy plan is needed to fill the gap.

Making the plans

Such energy plans are worked out in the second part of the book, called 'Energy plans that add up'. MacKay sees four possible contributions to fill the gap: 1) reducing energy consumption by using more efficient technology, 2) coal fired generation with carbon capture and storage, 3) nuclear energy, and 4) importing renewable energy from regions that have plenty of sunshine, mainly the Sahara Desert.

Concerning the reduction of energy use, MacKay focuses on two large fossil fuel consuming functions, namely heating and transport. Each of these functions are responsible for approximately 40 kWh per person per day. The book proposes to entirely electrify both functions, through the use of electric vehicles and heat pumps. This has a double advantage: it significantly reduces energy consumption and the energy that is still required can be produced by carbon free power generation systems.

Meeting the demand that is left

Meeting the remaining energy demand after switching to high efficiency electrical technology can be accomplished in various ways. But each has certain drawbacks. Generating all required electricity — after efficiency improvements — by domestic renewables is not completely impossible, but would still demand a high price from the countryside and seaside. To complement domestic renewables, coal fired power plants with CCS can be used, but MacKay points out that they are not really sustainable on two counts. The first is obviously that the global coal reserve is finite and therefore not truly sustainable. His second point is that there is also a significant amount of carbon dioxide released during the coal mining process. Importing solar energy from the Sahara Desert is the most sustainable option from an environmental point of view, but might raise geopolitical problems. Nuclear energy has the disadvantages of nuclear waste and safety issues, but MacKay puts those drawbacks into perspective by comparing it to other waste and safety issues around the world.

By combining the various options in different ways, the book draws six possible plans for a zero-carbon economy in the UK, without expressing any preference between them. It invites the reader to compose their own preferred zero-carbon energy plan, which is made easier thanks to the transparent figures that are provided. The principal message MacKay wants to pass on to the reader is that the energy plans need to 'add up' before they are worth considering.

The last two chapters of the book are dedicated to a more specialized audience, providing technical details on energy systems and useful data that back-up the figures provided in the first part of the book.

References

You can freely download the book 'Sustainable Energy — Without the Hot Air' by David MacKay at his website