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Without the Hot Air (changes)

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David MacKay examines different ways of providing sustainable energy and considers a range of options appropriate for UK, which are also later recalculated for EU, US and the World. It has 360 pages with lots of pictures relating to energy transformations. The main two first parts are 250 pages and probably what most people will read. the last part contains high-school physics for the chapters in part one. The final part has an extensive bibliography and a quick reference on energy matters.

This book is on our list of recommended reading. Here we try to do a critical reading of Sustainable Energy Without the Hot Air.When he wrote the book and published it the concentration of carbon dioxide was 384-386 ppm in the atmosphere. The current scope of the review is part one and two of the book (chapter 1-32).


The book is framed by one short chapter on global warming and he chooses to focus on energy generation, energy use, energy distribution and energy storage. Where the book is unusual is that he puts appropriate numbers on everything and has very simple explanations on how to do sums and balances in your own energy book.

Personal Balance sheets

His main motivation for writing the book is summarized as quantifying the debate on sustainable energy. He also mentions the drivers for energy policy: peak oil, secure energy? supply and anthropogenic global warming. At the time his book was written, greenhouse gas emissions amounts to roughly 5.5 tonnes CO 2eCO_2e/year per person. Or if we zoom in and look at countries:

Here we see that largest CO 2CO_2 polluters are the USA, Canada, and Australia. MacKay then has a cumulative figure, where sums CO 2CO_2 emissions over all time. So if one wants to make the polluter pay, this might be an aspect of that. (Another is “follow the individual income, which Socolow and Pacala have proposed recently.)

This could of course be combined to making rich long-term polluters pay more. Just to emphasize that climate change is essentially an energy problem, MacKay has this figure:

In the rest of the chapters in the first part Numbers, not adjectives he introduce an intuitive method focusing om the individual energy use - red blocks - and energy production - green blocks. Units are also made more personal by using the energy analog to water and water flux; kWh for energy and kWh/day for power. When its feasible MacKay uses energy quantities per person to facilitate quantification in other countries. This way of doing things resemble what we do in our daily lives, check the energy meters and making household budgets, build LEGO with the kids, so its an attractive and workable approach.

Using UK as the example in this part he arrives at the conclusion that today (2006) UK consumption 195 KWh/day per person is not balanced up with the projected production of renewable energy 180 KWh/day per person. Spread over the categories that David MacKay used in the first part of the book, on page 103:

Energy ConsumptionRenewable energy production
Defense: 4Geothermal power: 1
Transporting stuff: 12Tidal power: 11
Stuff: 48Wave power: 4
Food,farming: 15Deep offshore wind power: 32
Gadgets: 48Shallow offshore wind: 16
Light: 4Hydro power: 1.5
Heating/cooling: 37Biofuel: 24
Jet flights: 30Photovoltaic solar power farms: 50
Car: 40Photovoltaic solar power on house: 5
Concentrated solar power heating on house: 13
Onshore wind farms: 20

So he chooses one of the two latter solar power options with the assumption that houses generally lack roof space to fit both. At the end he mentions two of his conclusions for the first part of the book:

  1. To make a difference, renewable facilities have to be made country-sized.
  2. It is not going to be easy to make a plan that adds up using renewables alone.

Making a difference

In chapter 19 he dispels the myth that “every little helps”. Every little bit is too little, and it makes us less keen to focus on the big necessary changes concerning energy consumption and production. To reduce consumption, we need to focus on reducing our population, changing our lifestyles, and energy efficient technologies. For the latter. Dr MacKay introduces the notion of “sustainable” production and defines it as being able to last 1000 years.

MacKay details this further and point out that we have to work with several energy efficiency and technological innovation alternatives—heat pumps in order to electrify house heating in chapter 21, electric cars and electric public transportation in chapter 20. He also adds a mixed bag of green technologies in chapter 22-26; own UK renewable energy, other countries renewable, coal with Carbon capture and storage and nuclear power until the Jevons paradox may happen in about 60 years, assuming global coal reserves of 1.6 Teraton and consumption rate 6.3 Gt/year and consumption growth rate of 3.4%.

MacKay has an interesting discussion in the second part, chapter 26 on how to handle electricity fluctuations and energy storage before arriving to the different energy plans. For the sake of simplicity he assumes that cartoon UK he focuses on the big posts in the energy budget: heating, transport and electricity consumption 125 kWh/day per person

  • Make sure your policies includes a plan that adds up!

So the electrification of heating and transport, results in energy consumption in 2050 in 30 kWh/day per person (pp) and 20 for the latter and energy for electric things stays constant at 18 kW/day pp. So 68 in total and transport is assumed to be 18 kWh/day pp electricity and 2 kWh/day pp from bio-fuels. Heating is 12 kWh/day pp electricity, pumped heat 12 kWh/day pp, wood 5 kWh/day pp, and solar 1 kWh/day pp. The electricity consumption increases to 48 kWh/day pp due to electric cars and pumps. So these are the common parts of cartoon UK in 2050. From this he creates five plans for UK:

Plan D - Domestic diversity, the lion’s share is coal with carbon capture and storage (clean coal) and nuclear power each with 16 and pumped heat 16 kWh/day pp. Plan N - Not in my backyard ,NIMBY, has as main contributors desert solar power 20, clean coal 16 and pumped heat 16 kWh/d pp. Plan L (liberal democrats wants no nuclear) the three largest contributors are desert solar 20, clean coal 16, pumped heat 12 kWh/d pp.

The green plan G, contains mainly desert solar 7, pumped heat 12 and wind 32 kWh/day pp. Plan E for economics with a free market, nuclear 44, pumped heat 12 and wind contributes the most.

From these plans he makes a plan M - middle - which illustrates both the power density problem with renewable power in the UK and also the detailed cost and areal requirements of implementing plan M. The cost for this is total 870 billion pound or per year for his 40 year scenario it is 21 billion pound /year or less than one percent of the GDP of UK for 2009.

Or in his figure 28.5 left side in between the annual profits of Shell and what people spend on makeup!

Chapter 30 he does the calculation by adding some industry energy consumption so the assumed consumption is closer to Hong Kong, 80 KWh/dpp. For EU it adds up to wind 9, hydro 6.4, wave 2, tide, solar 7 and bio 12 and photovoltaic solar power farms 54. But he claims that the main problem with photovoltaic technology is the cost. So excluding that he adds up the renewables to 42.6 kWh/dpp. So, the EU

can’t live on its own renewables. So if the aim is to get off fossil fuel, Europe needs nuclear or solar power in other people’s deserts or both.

North America - US,Canada and Mexico can live on their renewables provided that they reduce todays consumption of 250 kWh/dpp to half and include solar photovoltaic farms.

And if the world can consume 80 kWh/dpp he gets wind 24, water 1.4, tide 0.2, wave 0.5, geothermal 8, which adds up to 36. so:

We have a clear conclusion: the non-solar renewables may be “huge” but they are not huge enough. To complete a plan that adds up we must rely on one or more forms of solar power. Or use nuclear power. Or both.

Details for Some Chapters in the Second Part

Chapter 20 treats how to electrify land transport and achieve a substantial reduction in energy consumption, by aerodynamic design and efficient driving techniques, and by using public transport. The latter is upto 10 times better than car. For the person who still prefers he proposes bicycles and efficient biking facilities, and electric and hybrid cars with regenerative breaks. It can lower city driving energy use with 20 %. Hybrid cars also gives 20-30 % more energy efficient cars. MacKay has a very good summary in figure 20.23 on page 128 on different forms of passenger transport:

E-cars can deliver 15 kWh / 100 km - five times better than the car today. Aircraft’s are already are so highly optimized and they are already close to the physical limits of aerodynamics and independent of its size has to spend 0.4 kWh/ton per km to stay up and keeping its optimal speed for which it was designed. So lowering the speed of a plane would result in higher energy consumption.

In chapter 21 he suggest three ways to achieve higher efficiency by reducing the average temperature difference, reduce leakiness and increasing the heating system efficiency. in Britain each degree Celsius lower temperature results in 10% less energy used.

Chapter 24 Nuclear? professor MacKay makes fission sustainable by limiting consumption in order to last 1000 years. And provided we can make ocean extraction economically feasible we can get the following power from uranium:

Chapter 29 is short but very important and deals with how to achieve incentives and motivation for changing behavior of carbon emission on an individual and societal level and how difficult that is. He presents the current state of European carbon trading 2005-2007 - which he claims is “the way to close the stable door is to create a market in permits-to-leave-the-door-open”. He proposes carbon taxes, individual actions and energy R&D instead.


General issues

One thing that Dr MacKay has in abundance are diagrams and figures, which might be a mixed blessing for the general audience and decision makers. Confronting linear-logarithm plots on page 7 might put them off. But for the scientific and engineering community having it collected in one place is good. As long he stays to the energy topic his writing is crystal clear for most of the book up to chapter 26. But there are a couple of areas where his reasoning is a bit confusing, in the last 5 chapters of the book.

Also just focusing on the energy quantification’s misses the chance of communicating how serious the problem with global warming has become. See Eaarth. Furthermore all of MacKay plans and reasoning, makes it more of a plan B. More details and numbers about energy in the UK, and some rough estimates for the world, but still the optimistic tone that it might be bad with greenhouse gases in the air, but there is still time. This neglects the fact that global warming has been around for three decades and people are still not changing their individual behavior.

Numbers not adjectives

He claims correctly that on p.14, that carbon dioxide will hang around 50-100 years, which is valid for 50% of CO 2CO_2 and 30 % for the latter time, but the remaining 20 % will stay for many millenniums. So it would be more transparent to admit upfront that there is a high probability that Carbon is forever in the atmosphere and give the potential reader higher incentives for demanding resiliency in their energy systems and saying yes to sustainable energy. He actually has a diagram 31.4 on p.243, but at the far end of the main part.

Chapter 6 in the first part feels incomplete which deals with Geothermal power. UK has a lot of experience in this area worth sharing and also it would have been good to see how much of the infrastructure that could potentially be reused and its energy transformation potential. See the book by Godfrey Boyle in the References.

A quick check on page 103 from another source and the book by professor Boyle has an estimate for UK in 2025 in table 10.1 and figure 10.5. Using his technical potential column—which agrees most with Dr MacKay’s reasoning around sustainable nuclear power later in his book. Boyle has 14.5 KWh/day/p for land based wind power. In the same units offshore wind: 160, solar heating: n/a, photovoltaic: 12, wave: 27, small hydro (large hydro is fully developed): 1.8, tidal wave: 1.6, landfill, waste: 1.8, biocrop: 1.5 so total biomass is 3.3, geothermal: 2. This adds up to 220 KWh/day/person.

So David MacKay is in the same ballpark to Boyle even when he is making a summary for cartoon UK. Also we should remember that Boyle did an estimate—also pretty good for an estimate—and MacKay is also diligent in checking his own calculations on pages 104-107 where he compares to several offical sources. But Boyle can live on his renewables while MacKay can’t. Assuming MacKay is right we have the premises for the second part.

Making a difference

He addresses similar actions as Stabilization wedges in this part: efficiency, conservation, fission, carbon capture and storage, renewable energy but Stephen Pacala and Robert Socolow did not address technological innovation, making fission sustainable (last longer), and has a less complete set of renewable energy energy resources. David MacKay is more argumentative when presenting pros and cons for different alternatives. But David has six years of further global warming knowledge at his hands and also considerably more space in the book. His rationale on p.224 for limiting the book to how to make energy sustainable

One major problem is his redefinition of sustainable energy and in particular the term “sustainable” MacKay uses, which suddenly becomes something very 2-dimensional. Maybe he should use the term “cartoon sustainability” instead.

And related to this is the indirect re-definition “renewable energy” which in the first part is a “renewable” and in the second part it is not included directly in any of the sums, but separately as “non-solar” renewables plus solar power (and/or nuclear). Its not directly wrong but confusing and any the majority of books on renewable energy do not make this distinction (yes we all know that in the long run the Sun is not renewable but I do not think that this is Davids intention).

The plans D, N, L, G,E and M over a time span of 40 years should perhaps consider a wider spectrum of energy innovation than just better efficiency and electrification of transport and heating. Yes the innovation cycle for energy innovation is very long, but there would be good to get information on what is predicted to happen in energy research

His economical calculations are a bit flawed in some places not the sums but the economical reasoning. He states clearly in the beginning that he is not an economist but still he cannot keep his hands from the cookie jar, when given a chance. The economic argument has to be there for the whole picture to emerge, but sometimes it becomes almost one-dimensional. On pages 214-221 the reader should be made aware of how much the 870 billions are per year - which is still just a rough estimate - and perhaps as percent of the GNP. But he spends too many pages on getting the reader to get a feeling of the concept of billion, instead of putting the annual cost in diagram 28.6 and perhaps comparing it to the Stern review numbers.

Further Comments

Robert Smart remembers early drafts of SEWTHA in which Nuclear power was marked as unsustainable, with an expected life under 100 years, and suitable only as a stopgap. Later versions reduced the time frame of sustainability from infinity to 1000 years and Nuclear made the cut based on proven improvements in reactor technology over what is currently deployed, and the adequate EROEI of lower grade sources of Uranium (even sea water). The book documents the difficulties of covering British energy requirements with other carbon free sources.