“Sustainable Energy – without the hot air” is a book by David MacKay. It’s a thorough but clear analysis of how Britain could attempt to satisfy its present power-requirements without trashing the climate.
The book is available on the web for free download as a PDF and in other formats. David is more interested in having the book read than in making a profit from it. If you’d like to have a taste before reading the whole book, you can start with the 10-page summary he also provides on his site.
I think this is one of the most important books on tackling climate change that I have come across. Anyone who wishes to understand the complex question of how to reduce the carbon footprint of a nation should definitely read it. There are several reasons why I think that, here are some of them.
Though David is a every inch a scientist, the book is written in plain english, you don’t need a PhD to understand it. That said, non-native English speakers may have to look up words like ‘twaddle’ in a dictionary from time to time.
David starts by considering how much energy the British need to run their daily lives. By converting all uses of energy to a single unit he can produce a simple yet useful picture that includes electricity, transport, heating, food, and other lifestyle factors. This makes it easy to see what part of our lives is responsible for consuming energy, which makes it easy to see where we should look if we want to make changes.
He does not promote or favour a particular technology as part of the solution. He is not pro-wind, pro-solar, pro-nuclear, or pro-clean-coal. Nor is he against any of these or other climate-friendly energy-generation technologies. He considers all possible contributions to lowering Britain’s carbon footprint. Then he goes on to see if any different mix of technologies can possibly meet Britain’s energy requirements, or if it simply doesn’t add up. This makes the whole book very easy to comprehend.
He keeps things simple by looking only at what could potentially be done, if we captured all the available sources of energy. So, he looks at the total amount of wave-power energy arriving along the entire Atlantic coast. He looks at the total solar power we could get if we put panels on every south-facing rooftop. He considers the power we could get from wind if we put up turbines everywhere we feasibly could. He clearly and concisely works out what we could hope to get if we deploy these and other technologies on a nation-wide scale.
He is fully transparent about everything he does. All his assumptions are explained, he tells us where all his numbers come from, and he gives references to the material he used. So you can check his numbers yourself, there is no need to decide if you trust him or not. It’s all there for you to verify. He also uses round numbers, rather than quoting calculations to 10 decimal places like Spock in Star Trek, so we can follow the big picture more easily.
He does not rule out anything for political reasons, or for ethical reasons. He concentrates strictly on the basic facts instead. As he says:
This book is emphatically intended to be about facts, not ethics. I want the facts to be clear, so that people can have a meaningful debate about ethical decisions.
I don’t want to feed you my own conclusions. Convictions are stronger if they are self-generated, rather than taught. Understanding is a creative process. When you’ve read this book I hope you’ll have reinforced the confidence that you can figure anything out.
These days, there is so much written about climate change and what we need to do about it, with so many people reaching different conclusions, that is can be very hard to know who to trust. Some authors have their own conclusions that they want to convince us to agree with, so they bias their writing. Some fail to take account of important factors, which makes their conclusions unreliable. Some are deliberately trying to mislead us, working to a hidden agenda, as happens in so many walks of life. Some, finally, are simply too difficult to understand, with complex arguments that non-experts have no hope of following. We live in a world where the opinion of an expert is considered suspect, and is often rejected because, being an expert, we believe that they must be biased.
The result is that we are left with a choice among different viewpoints without knowing the facts, without knowing who is right or wrong, who is honest and who is not, or who is trying to manipulate us for their own gain. That’s not a good position to be in. That’s why it’s refreshing to find a scientist who wants us to reach our own conclusions.
That, in a nutshell, is why this book is important. Rather than pushing an agenda, David wants us to understand the limits of what we can do, and must do. He looks at the possibilities to see how they adds up, and he wants us to understand how he does it.
energy use per Briton per day (left) and energy available in renewables (right)
David’s simple way of looking at how we use energy is to convert everything to kilowatt-hours
(kWh). One kWh is the amount of energy used by a 1 kW appliance left running for one hour. A 100 watt lightbulb running for 10 hours also uses 1 kWh. A 40 watt bulb would take 25 hours to use one kWh, and so on. Your electricity meter measures consumption in kWh, so it’s a sensible unit, we can all relate to it because it appears on our monthly bills.
Other forms of energy can also be expressed in kWh. Driving the mythical average car 30 miles (50 km) consumes about 40 kWh of energy in the form of petrol. So if your commute to work is a 30-mile round trip, 5 days a week, that uses about the same amount of energy as running a 1 kW heater all day long, every day. The heater would use 1 kW x 168 hours per week = 168 kWh per week, the car would use 40 kWh per day x 5 days, which equals 200 kWh. That’s close enough to being the same thing, as I’m sure David would agree.
Similarly, if you take one long-distance flight per year, that also works out to be the equivalent of 30 kWh per day for that year. So just getting to your holiday destination uses the same amount of energy as if you left a 1 kW heater on all day long, every day, for the whole year.
That’s not to say that these things are exactly equal. After all, if you do leave your heater on for a year, you won’t suddenly wake up in the Bahamas on New Year’s Day (more’s the pity!). But it does allow you to start comparing things. 1 long-distance-flight = commuting 30 miles per day to work for a year = a 1 kW heater left on all year long. So, if you want to reduce your carbon footprint, you might consider car-pooling with a colleague, which will halve your energy consumption for your commute. Or, if you could cut out that long-distance flight, that’s going to be twice as effective, equivalent to taking your car off the road completely!
David does all the other sums for us too. Heating accounts for 37 kWh per person per day. Lighting accounts for 4 kWh, electrical and electronic gadgets (such as computers, phones, stereos and vacuum cleaners) consume about 5 kWh. The food we eat requires about 15 kWh to produce, when you add up everything that goes into it. Consumer goods (from cars to newspapers and other things that we buy) come with a cost of about 49 kWh. That huge number comes up when you take account of the energy needed to produce the raw materials, manufacture the object, use it, and dispose of it. Packaging alone adds 4 kWh per day to our consumption.
So do you unplug your phone-charger, as we are often told to do? Sure, go ahead, though it won’t make much difference. Change your light bulbs and turn down your thermostat? Definitely some savings to be had there. Trade in that SUV for a real car? Great idea! Don’t overlook how much you can save in other ways, like not buying stuff you don’t need, and not throwing things out when there’s still some use in them. Small economies and reducing waste are always a good idea, but we need to make bigger changes, on a national scale, if we want to save the planet.
David also tackles the question of how to look at the energy needs of the entire country. This is where many analyses come unstuck. For example, take the recently announced wave and tidal energy projects in Scotland. These are described with phrases like “major milestone”, and “Saudi Arabia of marine power”. These projects between them will yield the same amount of electricity as a large nuclear power station. That sounds impressive, but is it really? Could we simply build more of these and satisfy our energy needs that way?
David MacKay points out that Britain has about 1000 km of Atlantic coastline, and the waves crossing it have an energy of 40 kW per metre of coastline. If we build wave-machines that can collect half of that, and build enough to cover half of our coastline, we would get (drum roll please) 4 kWh per person, per day. [update: See also "Tidal power - no thanks" in New Scientist]
That’s not so much after all, just enough to keep the lights on. Is it worth covering half the coastline with wave machines for that? It certainly doesn’t sound like Saudi Arabia to me!
Using a similar approach, David calculates that if we were to cover one tenth of Britain with windmills, that would give us each 20 kWh per day, or one sixth of what we currently use. Covering every south-facing roof with solar water-heating panels would give us 13 kWh per day. Biofuels? If we converted all the farmland in Britain to producing biofuels, that would give at most 36 kWh each per day (and no more food!).
David MacKays five plans for powering Britain
David then goes on to consider what mix of technologies might be used to balance the energy needs of the UK in some foreseeable future, and proposes a number of simple plans to illustrate the possibilities and the limits of what might be achievable. Rather than go into details about them here, I’ll let you read the book for yourself and see if any of them appeal to you.
If you have the slightest interest in sustainable energy, I urge you to read this book. It’s the best illustration I’ve seen of what it means to wean a nation off of fossil fuels. That’s something that is really difficult to grasp, it’s such an enormous undertaking, yet David presents it in a way that makes sense. If you don’t want to let yourself be fooled by people with their own bias or hidden agenda, this is the book you need.