Group items tagged

This river of reading material and advertising junk pouring through our letterboxes contains energy. It also costs energy to make and deliver. Paper has an embodied energy of 10 kWh per kg. So the energy embodied in a typical personal flow of junk mail, magazines, and newspapers, amounting to 200 g of paper per day (that’s equivalent to one Independent per day for example) is about 2 kWh per day.

A new car’s embodied energy is 76 000 kWh – so if you get one every 15 years, that’s an average energy cost of 14 kWh per day. A life-cycle analysis by Treloar, Love, and Crawford estimates that building an Australian road costs 7600 kWh per metre (a continuously reinforced concrete road), and that, including maintenance costs, the total cost over 40 years was 35 000 kWh per metre.

We use about as much to heat and cool ourselves (in Britain) as we use to move around in our cars, while lighting uses onlu a graction of that energy - especially using low energy fluorescent bulbs or the new generation of LED lights. Hydro-electric power in Britain, however, even with generosity from the wet Highlands, will only deliver about one third of the small amount of energy we use to light ourselves. How unfortunate that such accidental power-concentrators as mountains and streams are not more plentiful, and not just, maybe, for the energy benefits.

Feb 7 2009. Join the Group Read. Chapters 5 and 6. Flight and Solar Will solar energy technologies allow us to sustainably take those long-haul flights to get our winter dose of sunshine? On the way, we discover that flying intecontinentally once per year has an energy cost slightly bigger than leaving a 1 kW electric fire on, non-stop, 24 hours a day, all year, despite the fact that modern planes are twice as fuel-efficient as a single-occupancy car. It may be no surprise, therefore, that Airline businessman Michael O’Leary, CEO of Ryanair, has developed a Swiftian the solution to the problem: " The best thing we can do with environmentalists is shoot them."

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).

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 ...

Figure 15.8. Energy requirements of different forms of freight-transport. The vertical coordinate shows the energy consumed in kWh per net ton-km, (that is, the energy per t-km of freight moved, not including the weight of the vehicle). See also figure 20.23 (energy requirements of passenger transport).

Dieter Helm and his colleagues in Oxford estimate that under a correct account, allowing for imports and exports, Britain’s carbon foot- print is nearly doubled from the official “11 tons CO2e per person” to about 21 tons. This implies that the biggest item in the average British person’s energy footprint is the energy cost of making imported stuff.

In which we learn that to get by on wave power you need to be very very insular -- that is, have a small number of people per unit length of exposed coastline (sounds like a nice place to me, but the British Isles don't fit the description) -- and also that our food habits, especially for red-blooded carnivores with meat-eating pets -- amount to more than half our driving habit in energy. There is a real energy case to be made for vegetarianism (approximately twice as efficient) and even more for veganism (another doubling).

The typical diet has an embodied energy of roughly 6 kWh per kWh eaten. Coley (2001) estimates the embodied energy in a typical diet is 5.75 times the derived energy. Walking has a CO2 footprint of 42 g/km; cycling, 30 g/km. For comparison, driving an average car emits 183 g/km.

All the energy saved in switching off your charger for one day is used up in one second of car-driving. The energy saved in switching off the charger for one year is equal to the energy in a single hot bath.

It’s been estimated that making each unit of petrol requires an input of 1.4 units of oil and other primary fuels (Treloar et al., 2004).

The total amount of car travel in the UK is 686 billion passenger-km per year, which corresponds to an “average distance travelled by car per British person” of 30 km per day.

I want to estimate the energy consumed by someone who chooses to drive

But electrical energy can also be converted to chemical energy. In an alternative world (perhaps not far-off) with relatively plentiful electricity and little oil, we might use electricity to make liquid fuels;

This heated debate is fundamentally about numbers.

if everyone does a little, we’ll achieve only a little.

BP’s website

Many tidal energy extraction systems are just extracting energy that would have been lost anyway in friction.

over 30 years.

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.

It’s been estimated that the average person’s lifestyle consumed a power of 20 kWh per day

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.

completely forested the country

As for a 500 ml water bottle made of PET (which weighs 25 g), the embodied energy is 0.7 kWh – just as bad as an aluminium can!

Computers Making a personal computer costs 1800 kWh of energy. So if you buy a new computer every two years, that corresponds to a power consumption of 2.5 kWh per day.