Sustainable Energy - without the hot air

Prof MacKay's starting point is that there is a great deal of vague flummery talked about energy production and consumption. It is easy to make vague claims of "huge" potential green sources or to obsess over what turn out to be very minor energy savings. His goal in this book is to have a hard-nosed discussion of real numbers, so that there can be a more sensible discussion of options. He avoids making explicit recommendations, but his one continual plea is that we create a plan that "adds up" rather than merely reflecting wishful thinking. The world currently consumes enormous quantities of fossil fuel, so any viable alternative plan also has to deal with very large numbers, either as savings or as alternate sources.MacKay writes in a very readable and entertaining style. But he is also very careful to explain his numbers and to build his scenarios from the ground up. I found his analyses convincing and stimulating. Sometimes more detailed or more mathematical analysis is pushed off to supplementary appendices, but those are also well worth reading.I learned many things. One key factor I hadn't appreciated was the enormous land areas required for renewable sources, such as wind, solar, biofuel, or geothermal to make a substantial difference. For example, MacKay calculates that it would probably require 10% of the UK's surface to be dedicated to wind farms in order to make a significant contribution to the UK's current energy needs. Even larger areas are required to generate meaningful quantities of biofuel. If an area the size of Africa were dedicated to growing biofuel, that might only replace a third of current world oil needs. But MacKay also points out there may be places where building vast energy farms makes sense. For example, a 20,000 square km solar power farm in the Sahara could be one way to meet the UK's energy needs.MacKay explains how technologies such as electric cars or heat pumps reduce energy needs, independent of how the electricity is generated. He shows us that because electric motors are extremely efficient, burning oil in a central power plant and using the electricity to run an electric car actually requires much less energy than traditional cars. Similarly, he shows how using a central electric power station to power home heat pumps is a significantly more efficient way to heat houses than burning gas or oil at the house. (I had definitely not understood this before!) MacKay would prefer we use green technology to create the electric power, but it is interesting that even using fossil fuel power stations, electric cars and heat pumps still reduce overall fossil fuel consumption.In his concluding chapters, MacKay outlines several possible plans that "add up". All of them have significant negatives, either through reliance on nuclear power, or enormous environmental impact, or enormous expense. He doesn't pick a winner from among these options, but he emphasizes that we need to chose a plan rather than simply saying "no" to every possible option.Regardless of whether you agree with Prof Mackay's goal of shifting to alternative energy supplies, this book is definitely worth reading. MacKay succeeds admirably in explaining the raw numbers, so we can see what realistic energy choices are available.Having read this book (and having it available as a reference) I now feel much better equipped to read the plethora of ideas, plans, suggestions, trivia, wishful thinking and occasional good sense that circulate around energy policy. MacKay is right that numbers matter, and plans need to add up!

...because I was so engrossed.First, I want to congratulate MacKay for being all about the numbers. He has his opinions, sure. But, in the end, what really matters with CO2 is boring old arithmetic: How much does it cost? How long will it last? How much energy can be delivered? How much energy can be saved? How much space will it take? More than anything else, he provides us with an intellectual toolkit on how to measure different approaches. Taking the basic raw numbers, such as incoming sunlight and available surface area, multiply them by an efficiency factor. Simple, elegant, powerful.His approach also tells us where OUR own greatest energy use, as individuals, is likely coming from. Which tells us where WE can improve and where we should not bother.Now, I don't agree with everything he says, but the observations below by no mean justify any less than 5 stars:- Nuclear power may not be renewable, but say a 100 year supply of uranium would nicely tidy us over till we found other energy sources. So it shouldn't be dismissed that quickly.- His numerical analysis is relentlessly English in outlook. England's geography imposes a fairly specific set of constraints that would apply differently to other countries. Which he admits - noting for example that the US could make solar energy work in its southwest deserts, as England could not. That's not so much a flaw with the book as, well, a feature. We need another edition for Canada and the US.- I am not always fully convinced by his calculations. For example, he relates fuel consumption in cars to the cube of the speed, IIRC and backs it up with some empirical data. And also links it to the number of stop/starts in city driving. But, one of the most common recommendations we hear to save gas is to accelerate slowly which really does not appear in his calculations. Are we getting the full picture? I think a broader admission of the need for "engineering fudge factors", not just simple predictive equations, would have been welcome.- Costs are not covered much. Seeing as there is only so much money around, the best solution may be the one which is affordable, not just the best that is theoretically possible.Honestly, I am only mentioning these points to highlight how little there is to criticize about this book. Praising it with faint criticism if you wish. If only more of the climate change advocates were as rigorous in their analysis we would have much better much better sets of policy options to choose from. It is one thing to convince people that climate change is happening, another to convince them to take action, potentially at personal cost. If you then mess that up by prescribing insufficiently thought out, dogmatic, solutions that is really a shame. This book is a huge step towards teaching us how to analyze possible solutions critically.Finally, one of his most important points is that we can't _always_ say NO to everything. Most renewables DO take up space and they DO change the environment. My area has had years of impact studies to birds and scenery of offshore wind turbines. Ditto run-of-river hydro objections. What it hasn't had is much new generation capacity.