For the impatient reader

Electricity Freedom System

Ultimate Guide to Power Efficiency

Get Instant Access

Are you eager to know the end of the story right away? Here is a quick summary, a sneak preview of Part II.

First, we electrify transport. Electrification both gets transport off fossil fuels, and makes transport more energy-efficient. (Of course, electrification increases our demand for green electricity.)

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 collaborations, 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.

Questions? Read on.

20 Better transport

Modern vehicle technology can reduce climate change emissions without changing the look, feel or performance that owners have come to expect.

California Air Resources Board

Roughly one third of our energy goes into transportation. Can technology deliver a reduction in consumption? In this chapter we explore options for achieving two goals: to deliver the biggest possible reduction in transport's energy use, and to eliminate fossil fuel use in transport.

Transport featured in three of our consumption chapters: Chapter 3 (cars), Chapter 5 (planes), and Chapter 15 (road freight and sea freight). So there are two sorts of transport to address: passenger transport, and freight. Our unit of passenger transport is the passenger-kilometre (p-km). If a car carries one person a distance of 100 km, it delivers 100 p-km of transportation. If it carries four people the same distance, it has delivered 400 p-km. Similarly our unit of freight transport is the ton-km (t-km). If a truck carries 51 of cargo a distance of 100 km then it has delivered 500 t-km of freight-transport. We'll measure the energy consumption of passenger transport in "kWh per 100 passenger-kilometres," and the energy consumption of freight in "kWh per ton-km." Notice that these measures are the other way up compared to "miles per gallon": whereas we like vehicles to deliver many miles per gallon, we want energy-consumption to be few kWh per 100 p-km.

We'll start this chapter by discussing how to reduce the energy consumption of surface transport. To understand how to reduce energy consumption, we need to understand where the energy is going in surface transport. Here are the three key concepts, which are explained in more detail in Technical Chapter A.

1. In short-distance travel with lots of starting and stopping, the energy mainly goes into speeding up the vehicle and its contents. Key strategies for consuming less in this sort of transportation are therefore to weigh less, and to go further between stops. Regenerative braking, which captures energy when slowing down, may help too. In addition, it helps to move slower, and to move less.

2. In long-distance travel at steady speed, by train or automobile, most of the energy goes into making air swirl around, because you only have to accelerate the vehicle once. The key strategies for consuming less in this sort of transportation are therefore to move slower, and to move less, and to use long, thin vehicles.

3. In all forms of travel, there's an energy-conversion chain, which takes energy in some sort of fuel and uses some of it to push the vehicle

Figure 20.1. This chapter's starting point: an urban luxury tractor. The average UK car has a fuel consumption of 33 miles per gallon, which corresponds to an energy consumption of 80 kWh per 100 km. Can we do better?

forwards. Inevitably this energy chain has inefficiencies. In a standard fossil-fuel car, for example, only 25% is used for pushing, and roughly 75% of the energy is lost in making the engine and radiator hot. So a final strategy for consuming less energy is to make the energy-conversion chain more efficient.

These observations lead us to six principles of vehicle design and vehicle use for more-efficient surface transport: a) reduce the frontal area per person; b) reduce the vehicle's weight per person; c) when travelling, go at a steady speed and avoid using brakes; d) travel more slowly; e) travel less; and f) make the energy chain more efficient. We'll now discuss a variety of ways to apply these principles.

How to roll better

A widely quoted statistic says something along the lines of "only 1 percent of the energy used by a car goes into moving the driver" - the implication being that, surely, by being a bit smarter, we could make cars 100 times more efficient? The answer is yes, almost, but only by applying the principles of vehicle design and vehicle use, listed above, to extreme degrees.

One illustration of extreme vehicle design is an eco-car, which has small frontal area and low weight, and - if any records are to be broken - is carefully driven at a low and steady speed. The Team Crocodile eco-car (figure 20.2) does 2184 miles per gallon (1.3 kWh per 100 km) at a speed of 15mph (24km/h). Weighing 50 kg and shorter in height than a traffic cone, it comfortably accommodates one teenage driver.

Hmm. I think that the driver of the urban tractor in figure 20.1 might detect a change in "look, feel and performance" if we switched them to the eco-car and instructed them to keep their speed below 15 miles per hour. So, the idea that cars could easily be 100 times more energy efficient is a myth. We'll come back to the challenge of making energy-efficient cars in a moment. But first, let's see some other ways of satisfying the principles of more-efficient surface transport.

Figure 20.3 shows a multi-passenger vehicle that is at least 25 times more energy-efficient than a standard petrol car: a bicycle. The bicycle's performance (in terms of energy per distance) is about the same as the eco-car's. Its speed is the same, its mass is lower than the eco-car's (because the human replaces the fuel tank and engine), and its effective frontal area is higher, because the cyclist is not so well streamlined as the eco-car.

Figure 20.4 shows another possible replacement for the petrol car: a train, with an energy-cost, if full, of 1.6 kWh per 100 passenger-km. In contrast to the eco-car and the bicycle, trains manage to achieve outstanding efficiency without travelling slowly, and without having a low weight per person. Trains make up for their high speed and heavy frame by exploiting the principle of small frontal area per person. Whereas a cyclist"/>
Figure 20.2. Team Crocodile's eco-car uses 1.3 kWh per 100 km. Photo kindly provided by Team Crocodile.
Figure 20.3. "Babies onboard." This mode of transportation has an energy cost of 1 kWh per 100 person-km.
Figure 20.4. This 8-carriage train, at its maximum speed of 100 mph (161 km/h), consumes 1.6 kWh per 100 passenger-km, if full.

and a regular car have effective frontal areas of about 0.8 m2 and 0.5 m2 respectively, a full commuter train from Cambridge to London has a frontal area per passenger of 0.02 m2.

But whoops, now we've broached an ugly topic - the prospect of sharing a vehicle with "all those horrible people." Well, squish aboard, and let's ask: How much could consumption be reduced by a switch from personal gas-guzzlers to excellent integrated public transport?

Figure 20.5. Some public transports, and their energy-efficiencies, when on best behaviour. Tubes, outer and inner. Two high-speed trains. The electric one uses 3 kWh per 100 seat-km; the diesel, 9 kWh.

Trolleybuses in San Francisco. Vancouver SeaBus. Photo by Larry.

3-9 kWh per 100 seat-km, if full

3-9 kWh per 100 seat-km, if full

Figure 20.5. Some public transports, and their energy-efficiencies, when on best behaviour. Tubes, outer and inner. Two high-speed trains. The electric one uses 3 kWh per 100 seat-km; the diesel, 9 kWh.

Trolleybuses in San Francisco. Vancouver SeaBus. Photo by Larry.

7 kWh per 100 p-km, if full

21 kWh per 100 p-km, if full

7 kWh per 100 p-km, if full

21 kWh per 100 p-km, if full

Public transport

At its best, shared public transport is far more energy-efficient than individual car-driving. A diesel-powered coach, carrying 49 passengers and doing 10 miles per gallon at 65 miles per hour, uses 6 kWh per 100 p-km -13 times better than the single-person car. Vancouver's trolleybuses consume 270 kWh per vehicle-km, and have an average speed of 15km/h. If the trolleybus has 40 passengers on board, then its passenger transport cost is 7 kWh per 100 p-km. The Vancouver SeaBus has a transport cost of 83 kWh per vehicle-km at a speed of 13.5 km/h. It can seat 400 people, so its passenger transport cost when full is 21 kWh per 100 p-km. London underground trains, at peak times, use 4.4 kWh per 100 p-km - 18 times better than individual cars. Even high-speed trains, which violate two of our energy-saving principles by going twice as fast as the car and weighing a lot, are much more energy efficient: if the electric high-speed train is full, its energy cost is 3kWh per 100p-km - that's 27 times smaller than the car's!

However, we must be realistic in our planning. Some trains, coaches, and buses are not full (figure 20.6). So the average energy cost of public transport is bigger than the best-case figures just mentioned. What's the average energy-consumption of public transport systems, and what's a realistic appraisal of how good they could be?

In 2006-7, the total energy cost of all London's underground trains, including lighting, lifts, depots, and workshops, was 15kWh per 100 p-km - five times better than our baseline car. In 2006-7 the energy cost of all London buses was 32kWh per 100p-km. Energy cost is not the only thing that matters, of course. Passengers care about speed: and the underground trains delivered higher speeds (an average of 33 km/h) than buses (18 km/h). Managers care about financial costs: the staff costs, per passenger-km, of underground trains are less than those of buses.

Figure 20.6. Some trains aren't full. Three men and a cello - the sole occupants of this carriage of the 10.30 high-speed train from Edinburgh to Kings Cross.
32 kWh per 100p-km

Figure 20.7. Some public transports, and their average energy consumptions. Left: Some red buses. Right: Croydon Tramlink. Photo by Stephen Parascandolo.

9kWh per 100p-km

9kWh per 100p-km

Figure 20.7. Some public transports, and their average energy consumptions. Left: Some red buses. Right: Croydon Tramlink. Photo by Stephen Parascandolo.

The total energy consumption of the Croydon Tramlink system (figure 20.7) in 2006-7 (including the tram depot and facilities at tram-stops) was 9kWh per 100p-km, with an average speed of 25 km/h.

How good could public transport be? Perhaps we can get a rough indication by looking at the data from Japan in table 20.8. At 19 kWh per 100p-km and 6 kWh per 100p-km, bus and rail both look promising. Rail has the nice advantage that it can solve both of our goals - reduction in energy consumption, and independence from fossil fuels. Buses and coaches have obvious advantages of simplicity and flexibility, but keeping this flexibility at the same time as getting buses and coaches to work without fossil fuels may be a challenge.

To summarise, public transport (especially electric trains, trams, and buses) seems a promising way to deliver passenger transportation - better in terms of energy per passenger-km, perhaps five or ten times better than cars. However, if people demand the flexibility of a private vehicle, what are our other options?

Energy consumption (kWh per 100p-km)


68 19 6

51 57

Table 20.8. Overall transport efficiencies of transport modes in Japan (1999).

VW Polo blue motion (99 g/km) Toyota Prius (104 g/km) Honda Civic 1.4 (109 g/km) Audi A3 (143 g/km)

Average new car, UK (168 g/km) Lexus RX 400h (192 g/km)

Jeep Cherokee 2.8 (246 g/km) Average new car, USA (255 g/km) Honda NSX 3.2 (291 g/km) Audi A8 (338 g/km)

Jeep Commander 5.7 V8 (368 g/km) Toyota Land Cruiser Amazon 4.7 (387 g/km) Ferrari F430 (420 g/km)

500 emissions (g/km)

0 20 40 60 80 100 120 140 160 energy consumption (kWh/100km)

Private vehicles: technology, legislation, and incentives

The energy consumption of individual cars can be reduced. The wide range of energy efficiencies of cars for sale proves this. In a single showroom in 2006 you could buy a Honda Civic 1.4 that uses roughly 44kWh per 100 km, or a Honda NSX 3.2 that uses 116 kWh per 100 km (figure 20.9). The fact that people merrily buy from this wide range is also proof that we need extra incentives and legislation to encourage the blithe consumer to choose more energy-efficient cars. There are various ways to help consumers prefer the Honda Civic over the Honda NSX 3.2 gas-guzzler: raising the price of fuel; cranking up the showroom tax (the tax on new cars) in proportion to the predicted lifetime consumption of the vehicle; cranking up the road-tax on gas guzzlers; parking privileges for economical cars (figure 20.10); or fuel rationing. All such measures are unpopular with at least some voters. Perhaps a better legislative tactic would be to enforce reasonable energy-efficiency, rather than continuing to allow unconstrained choice; for example, we could simply ban, from a certain date, the sale of any car whose energy consumption is more than 80kWh per 100 km; and then, over time, reduce this ceiling to 60kWh per 100 km, then 40kWh per 100 km, and beyond. Alternatively, to give the consumer more choice, regulations could force car manufacturers to reduce the average energy consumption of all the cars they sell. Additional legislation limiting the weight and frontal area of vehicles would simultaneously reduce fuel consumption and improve safety for other road-users (figure 20.11). People today choose their cars to make fashion statements. With strong efficiency legislation, there could still be a wide choice of fashions; they'd all just happen to be energy-efficient. You could choose any colour, as long as it was green.

Figure 20.9. Carbon pollution, in grams CO2 per km, of a selection of cars for sale in the UK. The horizontal axis shows the emission rate, and the height of the blue histogram indicates the number of models on sale with those emissions in 2006. Source: The second horizontal scale indicates approximate energy consumptions, assuming that 240 g CO2 is associated with 1 kWh of chemical energy.

Figure 20.10. Special parking privileges for electric cars in Ann Arbor, Michigan.
Figure 20.11. Monstercars are just tall enough to completely obscure the view and the visibility of pedestrians.

While we wait for the voters and politicians to agree to legislate for efficient cars, what other options are available?

Figure 20.12. A roundabout in Enschede, Netherlands.

Was this article helpful?

0 0
Guide to Alternative Fuels

Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

Get My Free Ebook

Post a comment