David adopts an avowedly arbitrary definition of a sustainable burn rate: can a burn-rate be sustained for 1000 years? If yes, it is sustainable. That definition allow shim to relate the UK's coal reserves with a daily per person sustainable consumption rate --- there would be less than 1 kWh of electricity per person available from clean coal. But we consume 180 kWh/day/person, so clean coal is a stop gap --- it will not see our way of life go on for that long. This relies pretty crucially on the definition of sustainability, which I think is wrong for the purpose. David adopts what one might call the Ise Shrine notion of sustainability. The Ise Shrine was first built in 4BC and has been rebuilt, identically, ever since then every 20 years. It was last rebuilt in 1993. This is "sustainability" as in keeping on and on doing the same thing. David is ISe-esque in choosing our ability to do the same thing - burn British coal - for a very long time to come.

Many gadgets consume a surprising amount of power on standby. David cut his electricity consumption by half by making sure his "vampire appliances" were kept off. There are real savings available here. David and friends set up "ReadYourMeter.org" to try to encourage others to make this sort of saving. According to the International Energy Agency, standby power consumes a surprising8% of residential electricity.

Sustainable Energy - without the hot air

Least woolly of all is David MacKay’s book (which can be bought or downloaded free from www.withouthotair.com). Irritated by the waffle that often surrounds discussions of energy and climate change, Mr 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 and the back of an envelope.

How much energy does Britain use - and how much could we generate without burning fossil fuels? Physics professor David MacKay has been doing the sums.

The average winter-time temperature in English homes in 1970 was 13C. Today, 50% more than that is usually thought of as just about tolerable. There are three strategies for reducing the carbon footprint of keeping warm: reduce the temperature difference between the inside and outside; reduce heat losses from inside to outside and increase the efficiency with which energy is transformed into heat. The first two seem obvious and cheap solutions. We hear a lot about "nudging" as a policy, and this seems an ideal area for clever devices to make people aware that they could be heating less and leaking less heat. David does not mention my own favourite long term solution here---a widespread move to small exoskeletons as a substitute to housing: we should be able to walk around with our temperature control close to our bodies and our living spaces open to the elements. David makes a powerful argument for heat pumps rather than Combined-Heat-and-Power plants, and slips in a big fault-line in eco-politics versus eco-engineering: energy transformation efficiency tends to rise as scale rises, whereas green politics loves to decentralise and make solutions small and local. This chapter is full of low-ish tech, labor-intensive investments that make energy-efficiency sense today. This is just what government policy should be stimulating our economies with today.

For forest-dwellers, there’s wood. For everyone else, there’s heat pumps.

A final impediment to rational discussion of combined heat and power is a myth that has grown up recently, that decentralizing a technology somehow makes it greener. So whereas big centralized fossil fuel power stations are “bad,” flocks of local micro-power stations are imbued with goodness. But if decentralization is actually a good idea then “small is beautiful” should be evident in the numbers. Decentralization should be able to stand on its own two feet. And what the numbers actually show is that centralized electricity generation has many benefits in both economic and energy terms. Only in large buildings is there any benefit to local generation, and usually that benefit is only about 10% or 20%.

What’s a reason- able thermostat setting to aim for? Nowadays many people seem to think that 17 °C is unbearably cold. However, the average winter-time tempera- ture in British houses in 1970 was 13 °C!

Electrify transport. There's not much to beat trains+bicycles, and any government looking for a Keynesian stimulus should find lots of infrastructure opportunities here. David MacKay comes down softly on the car---which shows great realism---and finds that electrification is the only real solution there. He debunks hydrogen as a good energy carrier. Flying is a really tough case---there is not much that can be done to reduce its energy intensity. (I was sitting in an easyjet plane the other day that tried to convince me of its greenery by saying: "Flying contributes less CO2 than driving to the atmosphere" ...). Batteries are the way to go---though just wait for the peak lithium scares. David has an interesting aside on nuclear ships. If we could make the (political) world safe for small-scale nuclear power, maybe there's more than ships that could benefit.

The congestion charge would be proportional to the number of bleeps received; this charge could be paid at refuelling stations whenever the vehicle is refuelled. The radio transmitter/receiver would replace the current UK road tax disc.

there is no prospect of significant improvements in plane efficiency.

the amount of lithium may be a concern, especially when we take into account the competing ambitions of the nuclear fusion posse (Chapter 24) to guzzle lithium in their reactors.

So I conclude that switching to electric cars is already a good idea, even before we green our electricity supply.

Figure 20.23. Energy requirements of different forms of passenger transport. The vertical coordinate shows the energy consumption in kWh per 100 passenger-km. The horizontal coordinate indicates the speed of the transport. The “Car (1)” is an average UK car doing 33 miles per gallon with a single occupant. The “Bus” is the average performance of all London buses. The “Underground system” shows the performance of the whole London Underground system. The catamaran is a diesel-powered vessel. I’ve indicated on the left-hand side equivalent fuel efficiencies in passenger-miles per imperial gallon (p-mpg). Hollow point-styles show best-practice performance, assuming all seats of a vehicle are in use. Filled point-styles indicate actual performance of a vehicle in typical use. See also figure 15.8 (energy requirements of freight transport).

Chapter 18 was depressing --- the diffuse nature of renewables in the crowded UK basically means that a realistic view of their usage makes it clear we won't make it on local wind, tide, sun, geothermal, wood etc. Assume: a) we can't change energy per capita too much; b) we can't change the capita (ie no creepy population control) and we still want sustainability ... The basic solution is:  1. electrify transport 2.  electrify space heating 3. produce electricity with whatever local renewables we can, augmented by clean coal, nuclear and imported solar from desert regions. Sounds simple, no?

Second, to supplement solar-thermal heating, we electrify most heating of air and water in buildings using heat pumps, which are four times more efficient than ordinary electrical heaters. This electrification of heating further increases the amount of green electricity required. Third, we get all the green electricity from a mix of four sources: from our own renewables; perhaps from “clean coal;” perhaps from nuclear; and finally, and with great politeness, from other countries’ renewables. Among other countries’ renewables, solar power in deserts is the most plentiful option. As long as we can build peaceful international collabor- ations, solar power in other people’s deserts certainly has the technical potential to provide us, them, and everyone with 125 kWh per day per person.

a little adds up to a lot,” if all those “littles” are somehow focused into a single “lot” – for example, if one million people donate £10 to one accident- victim, then the victim receives £10 million. That’s a lot. But power is a very different thing. We all use power. So to achieve a “big difference” in total power consumption, you need almost everyone to make a “big” difference to their own power consumption.

March 30th 2009. Join the Group Read. Chapter 18. A first balance (Instructions on how to join are at the bottom of the original post) This is the first chapter attempting to balance-up consumption and production. While the story told so far of the raw energy potential from renewable sources shows an ecouragingly close race to maintain our rich lifestyles with sustainable energy sources, a little digging provides much disappointment. Between the potential and the realisation lies a factor of over 100! From a production potential of 180 kWh per day per person, we get to an actual production figure of just 1 kwh/d/p and a "realisable" estimate of 18 kwh/d/p---a full ten times less than our consumption. Looking at the heart of the physics problem, David MacKay points to the geographically diffuse nature of renewables: each person needs a huge amount of land, tidal exposure, wind per person to make the sums add up. The sustainable potentials, as David emphasises, need "country-sized solutions". "To get a big contribu- tion from wind, we used wind farms with the area of Wales. To get a big contribution from solar photovoltaics, we required half the area of Wales. To get a big contribution from waves, we imagined wave farms covering 500 km of coastline. To make energy crops with a big contribution, we took 75% of the whole country." Yet protection of species, habitats, nature, beauty etc. all move the same people who want to reduce fossil fuel dependency to limit the installations. Something will need to give to balance our energy ...