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I’ve been reading the online book that I mentioned the other day being written by Professor David J C MacKay of the Cambridge University Department of Physics. Its an absolutely incredible read and I wish there was something like it regarding energy issues in the United States.

Its a fairly easy read and it is, as he’s titled it, without hot air. I’m only about 200 pages in. So far he hasn’t gotten into the economics of the issue at all (I suspect he really won’t) but instead sticks mostly to providing the facts necessary to have an intelligent debate about energy related issues. In a nutshell, he mathematically breaks down how much energy each person in the U.K. uses on a daily basis and then attempts to determine if there are enough non-carbon emitting sustainable energy sources in the U.K. to satisfy all of those energy needs in perpetuity.

I’ve lifted sections and quotes from his book that I think are poignant. Normally I don’t like cutting and pasting this much of another person’s work but he’s doing this all on a non-copyright/commons basis. Like I said, he’s doing an incredible job.

This is his break-down of English energy use, per person on a daily basis:

Consumption Type Amount
Car 40 kWh/d
Air Travel 24 kWh/d
Air Temperature 24 kWh/d
Water Temperature 13 kWh/d
Lights 4 kWh/d
Gadgets 5 kWh/d
Food 12 kWh/d
Fertilizer 3 kWh/d
Stuff 48 kWh/d
Transporting Stuff 12 kWh/d
Defense 4 kWh/d
Total 189 kWh/d

Here is a more detailed view of some of the items encompassed in the larger categories:

kettle 1 kWh/d microwave 0.5 kWh/d
electric cooker 1 kWh/d electric oven 2 kWh/d
refrigerator 0.5 kWh/d freezer 2.3 kWh/d
tumble dryer 0.8 kWh/d airing-cupboard 0.25 kWh/d
washing machine 0.8 kWh/d dishwasher 1.6 kWh/d
Aluminum 3 kWh/d Packaging 4 kWh/d
Paper 2 kWh/d House-building 1 kWh/d
Car-making 14 kWh/d Road-building 2 kWh/d
Road freight 7 kWh/d Plastic 8 kWh/d

I don’t know exactly how much a kWh/d is. For our purposes its not necessarily important. Focus instead on the relationship between the numbers. Understand that your personal share in the creation of aluminum uses almost as much energy as your personal share of lighting. Understand how transportation and regulation of air temperature dwarf the rest of the energy you use.

And two astounding facts:

For instance, if you learn that a round-trip intercontinental flight emits nearly two tons of CO2 per passenger, then knowing the average emissions yardstick (51/2 tons per year per person) helps you realise that just one such plane-trip per year corresponds to over a third of the average person’s carbon emissions.

We spend about one third of our energy on controlling the temperature of our surroundings – at home and at work – and on warming or cooling our food, drink, laundry, and dirty dishes.

Remember that these are English consumption habits. Americans consume fifty percent more energy than the British. Recognize also that we are talking about current energy consumption, not current electricity consumption. This is important however because if we are to move away from a carbon-based energy infrastructure then, more-or-less, we will need to convert most energy consumption to electricity consumption. If we are to move to an electricity based society then we have to build massive amounts of new electricity generating capacity.

I think many people confuse “electricity” and “energy”; but electricity is only one way in which we get energy; most of us get most of our energy in forms other than electricity – natural gas and petrol, for example (for heating and transport, respectively). In fact electricity accounts for only one fifth of our energy consumption, so even if renewables could supply 80% of our electricity, that would represent less than one fifth of our current energy demand.

On Economics and Efficiency

And today, electricity from solar farms would be four times as expensive as the market rate.

Remember, he’s only focused on the United Kingdom. Solar (and wind) in various areas of the U.S. would be far more efficient than the same systems in England due to the environment and climate. Future energy solution will be country specific. There will be no universally applicable renewable energy solution. Each country will be forced to assess its own strengths and weaknesses and apply the solution which works best for it.

The energy yield ratio (the ratio of energy delivered by a system over its lifetime to the energy required to make it) of a roof mounted, grid-connected solar system in Central Northern Europe is 4, for a system with a lifetime of 20 years [Richards and Watt, 2007]; and more than 7 in a sunnier spot such as Australia. [An energy yield ratio bigger than one means that a system was A Good Thing, energy-wise.] Wind turbines with a lifetime of 20 years have an energy yield ratio of 80.

This is important

If we are going to go about any sort of revamping of the energy grid then we need to do it in the most carbon neutral way. To me, this means that the initial focus should be on building out that part of the infrastructure that has the highest energy yield ratio first. E.g., use carbon or hydro based energy to build wind capacity, then use the additional wind capacity to build out the solar infrastructure.

Offshore wind is tough to pull off because of the corrosive effects of sea water. At the big Danish windfarm, Horns Reef, all 80 turbines had to be completely dismantled and repaired after only 18 months’ exposure to the sea air. The Kentish Flats turbines seem to be having similar problems with their gearboxes, with one third of them needing replacement during the first 18 months.

I’ll include this potential deep offshore contribution in the production stack, with the proviso, as I said before, that wind experts reckon deep offshore wind is not economically feasible.

On the Assumptions MacKay is Making

I should emphasize how audacious an assumption I’m making. Let’s compare this estimate of British wind potential with current installed wind power worldwide. The windmills required to provide the UK with 20 kWh/d per person are fifty times the entire wind hardware of Denmark; seven times all the windfarms of Germany; and double the entire fleet of all wind turbines in the world.

Before moving on, I want to emphasize the audaciously large area – two thirds of Wales – that would be required to deliver this 16 kWh/d per person. If we take the total coastline of Britain (length: 3000 km), and put a strip of turbines 4 km wide all the way round, that strip would have an area of 13,000 km2. That is the area we must fill with turbines to deliver 16 kWh/d per person. To put it another way, consider the number of turbines required. 16 kWh/d per person would be delivered by 44,000 ‘3MW’ turbines, which works out to fifteen per kilometre of coastline, if they were evenly spaced around 3000 km of coast.

On the Size of the Project Confronting Us

Its not hard to understand why the Presidential candidates are describing what we face as the “Apollo Project” of energy.

To create 48 kWh per day of offshore wind per person in the UK would require 60 million tons of concrete and steel – one ton per person. Annual world steel production is about 1200 million tonnes, which is 0.2 tons per person. During world war II, American shipyards built 2751 Liberty ships, each containing 7000 tons of steel – that’s a total of 19 million tons of steel, or 0.1 tons per American. So the building of 60 million tons of wind turbines is not off the scale of achievability; but don’t kid yourself into thinking that it’s easy. Making this many windmills is as big a feat as building the Liberty ships.
For comparison, to make 48 kWh per day of nuclear power per person in the UK would require 8 million tons of steel and 0.14 million tons of concrete.

But please remember: in calculating our production stack we threw all economic constraints to the wind. Also, some of our green contributors are probably incompatible with each other: with our solar PV farm we assumed that we’d use 10% of the country, then with our energy crops we covered 75% of the country. If we were to lose just one of our bigger green contributors – for example, if we decided that deep offshore wind is not an option, or that paneling 10% of the country with photovoltaics is not on – the production stack would no longer match the consumption stack. Our estimate of a typical affluent person’s consumption has reached 200 kWh per day. It is indeed true that many people use this much energy, and that many more aspire to such levels of consumption. The average American consumes about 300 kWh per day.

MacKay’s Calculations

Making what he calls “audacious assumptions,” MacKay believes that the maximum sustainable renewable energy that the U.K. could generate is as follows:

Production Type Amount
Onshore Wind 20 kWh/d
Biomass 24 kWh/d
Solar PV farm (400 m2/p) 50 kWh/d
Solar PV 4 kWh/d
Solar heating 10 kWh/d
Hydro 1.5 kWh/d
Shallow offshore wind 16 kWh/d
Deep offshore wind 32 kWh/d
Wave 4 kWh/d
Tide 14 kWh/d
Geothermal 2 kWh/d

After covering the 10% of the windiest part of the U.K. with windmills, burning most of the U.K.’s waste output (food, biofuel, wood, waste, landfill gas), erecting a 65′ x 65′ solar panel for every person in the country, covering every roof with solar panels, maximizing hydro capacity, erecting a four mile wide band of wind turbines offshore around the entire island and maxing out wave, tide and geothermal production, MacKay concludes that the U.K. could conceivable produce a maximum of 173.5 kWh/d sustainable renewable energy.

That’s 15.5 kWh/d less than the average Brit consumes today.

It should be noted that MacKay acknowledges that this theoretical production is far in excess of any sort of practical production due to political/societal/economic restraints. Practical production is not the point of his exercise however. He is simply interested in whether it is theoretically possible for the U.K. to produce enough renewable energy to meet its current needs.

MacKay’s Conclusions

Realistically, I don’t think Britain can live on its own renewables – at least not the way we currently live. I am partly driven to this conclusion by the chorus of opposition that greets any major renewable energy proposal. People love renewable energy, unless it is bigger than a figleaf. If the British are very good at one thing, it’s saying “no.” Wind farms across the country? “No, they’re ugly noisy things.” Solar panels on roofs? “No, that would spoil the visual amenity of the street.” An expansion of forestry? “Ruins the countryside.” Waste incineration? “No, I’m worried about health risks, traffic congestion.

Stop saying “we’ve got huge renewables,” and do the sums. To make a difference, renewable facilities have to be country-sized. For any renewable facility to make a contribution comparable to our current consumption, it has to be country-sized. To get a big contribution from wind, we used windfarms with the area of Wales. To get a big contribution from solar photovoltaics, we required the area of Wales. To get a big contribution from waves, we imagined wavefarms covering 500 km of coastline. To make energy crops with a big contribution, we took 75% of the whole country.

To sustain Britain’s lifestyle on its own renewables alone would be very difficult. A renewable-based energy solution will necessarily be large and intrusive.

“Nuclear or wind?” is the wrong question. We need everything we can get our hands on – all the wind, and all the nuclear – and even then, we’re still in trouble.

This concludes MacKay’s examination of renewables. Next time I’ll review his examination of the possibilities of nuclear and clean coal.

Related Reading:
Part 1: Is There Enough Alternative Energy to Power the United States?
Part 2: Can the Electric Car Save the American Way of Life?
Part 3: How Much Renewable Energy Does the U.S. Produce?
Part 4: Carbon Sequestration. Of Jet Emissions?
Part 5: Professor David MacKay’s View of Future Britain’s Energy Use
Part 6: Wind Power: Can We Get to 300 GW by 2030?
Part 7: The Solar Pipe Dream?
Part 8: World Energy Consumption Per Capita
Part 9: Dealing With the Intermittency of Wind and Solar Power