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We need nuclear power if we’re going to meet the world’s growing need for energy while also eliminating carbon emissions.

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No Hot Air

Understanding energy use and technology

David MacKay’s brilliant book is a primer on how we make energy and its impact on the climate.


The noted climate researcher Ken Caldeira suggested I read Sustainable Energy - without the hot air by David MacKay. I’m grateful for his recommendation.

The book is available for free at: www.withouthotair.com where you can also buy it in hard copy.

There’s also a great video of MacKay that I really like.

I agree with Ken that this is one of the best books on energy that has been written. If someone is going to read just one book I would recommend this one. It isn’t an easy read but that’s because you learn so much. Even after you read this book you will want to keep it around since whenever you read about a new development in energy technology, the framework in this book will help you understand how important it is and where it fits in.

If someone wants an overall view of how energy gets used, where it comes from, and the challenges in switching to new sources, this is the book to read. The book isn’t a global warming book per se but it shows various ways to change our energy generation so it emits very little CO2.

The book is very numeric which is appropriate. MacKay uses kilowatt-hours-per-person-per-day to discuss everything. He has a great section that explains how articles about energy use different measures like number of households powered and how all these measures obscure the overall energy equation. His use of a common metric is critical to giving the reader a clear understanding of how we might get our energy inputs to match our overall energy needs in the future.

To avoid overwhelming the main text with formulas, MacKay uses the appendix to explain why cars, planes, or houses use as much energy as they do and how to figure out the potential energy from various new approaches like wind and tides.

The focus is on educating the reader rather than promoting a point of view. MacKay’s strongest point is that any plan for the future has to have enough energy sources to meet the demand. He thinks people ought to have a numeric sense of how their energy consumption adds up. He gives a lot of examples of things like the energy used for making grocery store plastic bags that won’t have a significant impact on reducing CO2 but that get far more attention than critical issues like how to dramatically improve the transmission network.

He focuses on the UK in early chapters but then extends that to the rest of the world. You might learn a bit more about British inlets that can be used for pumped water storage and the tides around Britain than you expected to but that is minor.

The book explains all the big categories of energy usage with great clarity and he explains what can be done to reduce usage in all of these areas. In Europe, for example, people use 125Kwh per day per person, including 40Kwh for transportation, 40Kwh for heating and cooling, and 45Khw to generate the 18Kwh of electricity they use each day.

MacKay thinks that new designs and electric engines can reduce transportation to 20Kwh and heating and cooling can be cut to 30kwh per person per day. He leaves direct electrical usage at 18Kwh per person per day since the improvements in areas like lighting will be offset by new uses of electricity. MacKay is very convincing that we won’t see usage fall much more than this despite all the great ideas for efficiency improvements.

Americans use 250Kwh per person per day so there are even more opportunities for efficiency, but still not enough to solve the problem of future energy sources.

The area where there is great uncertainty is what the sources of energy will be in the future. MacKay provides five different scenarios which vary according to how much solar, clean coal, nuclear, or wind they use.

MacKay does a great job of explaining the challenges that come with sources that don’t provide energy on demand 24 hours a day. Whenever you hear someone talk about the power output of a wind farm they are talking about the output during the time the wind blows which is typically one-third of the day. Solar is similar. As long as we are getting a modest amount of our power from these sources, other sources can be adjusted to make the total work out around the clock. MacKay explains that there is no magic storage technology today that would allow you to store extra power for the rest of the day. He talks about how costly and large the storage would be for the UK to get most of its energy from renewable sources.

It is possible that there will be a huge breakthrough in battery technology to help with this problem but it would be unwise to count on that. The scenario MacKay gives where electric car batteries are used for storage doesn’t seem realistic to me since batteries can only be cycled a finite number of times before they have to be replaced and it would take an amazing grid. He doesn’t mention the possibility of using rocks in connection with solar thermal energy plants to enable them to provide power over a 24-hour period.

Society is incredibly dependent on having a reliable power supply. It is easy to stockpile coal at a coal plant. The cost to having the same guaranteed availability for wind and sun would be very high.

MacKay also does a great job of explaining that changing to energy sources that only work well in specific locations requires a lot of investment and permitting for transmission lines. Today’s fuels can be moved from place to place but sun and wind cannot.

MacKay has one chapter focused on global warming and CO2. He talks about a scheme for capturing CO2 from the atmosphere which is worth exploring. I was surprised he didn’t mention geoengineering techniques to delay or reduce the effects of global warming. He also didn’t explain enough about other gases that cause global warming.

As you look at the possibilities for the UK you see that there is a huge question about whether it is reasonable to count on a high percentage of the power coming from the deserts of North Africa using solar photovoltaic or solar thermal technology. It can be done but does it create unaffordable political and reliability risk? The book offers only one plan that doesn’t count on nuclear, clean coal, or acquiring most of the power from a foreign country. Of the five scenarios, I think it is the least realistic since it uses so much wind and requires gigantic levels of storage.

One place where MacKay does have a strong point of view is that the amount of government R&D going into energy is pathetically low. The UK is spending less than £0.2 per person per year. The United States has raised its number but it is still way too low. If people understood that the only way to reduce CO2 emission by 80% is to have a large number of research breakthroughs, then perhaps this would change. Even the most optimistic scenarios for conservation will not get to 80% as long as cars, heating, and electricity generate CO2.

If people think that raising energy prices a little bit or just consuming a bit less will solve this problem, we will never achieve the required reductions. Regulations requiring electricity plants to move to low CO2 emission over a 40 year period would send a stronger market signal to power plant makers than any of the cap and trade systems that are likely to get implemented.

I was thrilled to see a book that is scientific, numeric, broad, open-minded, and well written on a topic where a lot of narrow, obscure, non-numeric writing confuses the public. People need to really understand what is going on and then be part of the process of moving the world to a new energy infrastructure.