Yes we can! But it's not gonna be easy - a refreshing look at global warming - September 2009

This is about a book on climate change for people who care about the environment but might not be physicists, climatologists, or politicians. The book is called Sustainable Energy: Without the Hot Air and is available in paperback or free to download on-line: www.withouthotair.com. There is also a downloadable ten-page synopsis which provides an introduction or summary for those without time to read more.

The author talks in an everyday English that non-professionals can understand. He also realizes that the huge numbers involved in so many discussions about alternative energy are so big as to be meaningless to many of us.

Irritated by the waffle that often surrounds discussions of energy and climate change, David MacKay, a physicist at Cambridge University, has chosen to illustrate the challenge of breaking our fossil-fuel addiction armed only with the laws of physics, reams of publicly available information, a calculator - and a lot of common sense.

The book's masterstroke is to express all forms of power consumption and production - the car, the washing machine, the wind turbine, the mobile phone charger, the nuclear power station - in a single unit of measurement. So rather than drown readers in a swamp of gigahertz, megawatts, joules, tonnes of oil equivalent and the like, he describes everything in terms of kilowatt hours per day (kWh/d). Put another way, one 40 watt light bulb, kept switched on all the time, uses one kilowatt-hour a day. Once we learn that driving the average car 50km a day consumes 40kWh/d, we can see that this is equal to the power needed to keep 40 40W light bulbs constantly lit for a day. This, MacKay argues, sharpens the debate by helping us to focus on the big things - such as how hopelessly undercooked our current plans for renewable energy are - rather than get distracted by "eco-gestures", such as believing you have done your bit by remembering to switch off the mobile phone charger. ("The amount of energy saved by switching off the phone charger is exactly the same as the energy used by driving an average car for one second. ...don’t be duped by the mantra “every little helps.” Obsessively switching off the phone-charger is like bailing the Titanic with a teaspoon. Do switch it off, but please be aware how tiny a gesture it is....If everyone does a little, we'll achieve only a little.")

Mr. MacKay favors no particular technology. He is concerned only that proposals to decarbonize the economy should add up. But his refreshingly hard-headed approach (confined to Britain, but easily adapted to other countries - including the Netherlands) comes to some sobering conclusions. Meeting Britain’s energy needs from onshore wind power would require covering literally the entire country in turbines - even assuming that the wind was guaranteed to blow. If only 10% of Britain were covered then wind could provide roughly a tenth of total demand. Switching every piece of agricultural land to biofuel production would provide just 12% of the requisite energy juice. 

It is a similar story for offshore wind, tidal and wave energy, all of which make the claims of green advocates in Britain (and other countries) that the country has a “huge” renewable resource look somewhat hollow, especially since the book ignores questions of costs and focuses purely on physical limits. To make a dent in fossil-fuel consumption without using nuclear power, renewable-energy facilities will have to be “country-sized”, with offshore wind farms bigger than Wales and huge solar-power arrays in sunny deserts piping power to cloudier nations.
This is how environmental science should be communicated; crystal clear text and honest graphs, with simplified theory and ballpark calculations that anyone can follow, backed up by empirical data as a check on results, real examples, frequent references, and explanations of limitations. Read it.

Scope of the problem. This concentrator photovoltaic collector can generate 138 kilowatt-hours per day, half the energy consumption of an average American per day. You would need two of these for every American if such collectors were the only energy source in the USA. Today there are 307 million Americans. There are, today, some 6.5 billion people on earth that aspire to achieve the same welfare level as achieved in the USA - with the consequent energy utilization.