No Green Sheep

This is the first in a multi-part series looking at different forms of transport.

Buses are generally loved by people who care about the environment. But, do they actually earn this reputation?

4-10 mpg

Different studies point to an average fuel efficiency of around 4-10mpg^1,2

40-100 pmpg (passenger-miles per gallon)

Statistics for the UK in 2008 state an average occupancy of 10 people on buses³. This means that buses get between 40 and 100 passenger miles per gallon.

Questionable Efficiency

Cars by comparison get 20 – 50 miles per gallon. So, a single person in a car is less efficient than a bus with 10 people on it. However, once you have two or more people in a car you’re starting to see that the car could be a winner. But, the same applies to a bus – get more people on the bus and it becomes more and more efficient for passenger miles per gallon.

An Undersold Perk

For me, one of the biggest perks of using a bus is that I can sit and read a book or listen to music. Why is this not advertised?

My brother has recently started using the train to get to work and he’s found that he likes it more than driving – his reason for this is that it’s no longer wasted time!

What Can we Do to Improve Buses?

Every improvement in average occupancy is going to lead to less fuel used per passenger mile. So, we need to think about how to improve this average occupancy. Several ideas spring to mind:

• Cut low-use bus services – my local service runs every 10 minutes during the day. Most of the time there are a couple of people on it. I would rather have a bus every 15 minutes during the day (and have it be on time due to a more relaxed schedule) than have them attempt every 10 minutes and fail.
• Encourage people to use the bus – I haven’t seen a single advert on TV encouraging people to use the bus. I see plenty of stop smoking adverts. Worth a shot I think.
• Reduce the number of seats – buses generally cram as many seats as possible onto a bus. Removing a single row of seats would give everyone more room for their legs and their shopping – leading to a more pleasant journey and (hopefully) an increase in average occupancy outside of peak times.
• Cheaper fares outside peak times

Are Buses Really so Great?

Busy buses are fantastic for efficiency. Empty/low-occupancy buses are bad. Either cut these services or get more people onto them.

References

1. Demonstration of Caterpillar C-10 Dual-Fuel Engines in MCI 102DL3 Commuter Buses
2. Long Beach Transit: Two-Year Evaluation of Gasoline-Electric Hybrid Transit Buses
3. Public Transport Statistics Bulletin GB: 2008 edition

I was recently informed that boiling water in a kettle on the hob requires less energy than boiling water in an electric kettle. I wasn’t convinced as the informer had no numbers to back it up. So, I’ve done a little research and found that it is actually true.

The Numbers

The sources I have come across ^{[3, 4]} indicate that ~30% less energy is required to heat on the hob in a kettle. However, as the output of the hob increases the wasted energy also increases – and the electric kettle starts to win.

Power stations often operate with an efficiency of less than 40% ^{[1, 2]}. Heating by using gas directly is roughly 55% efficient (meaning that 55% of the energy spent goes into heating the water).

The Reasoning

When you burn gas to heat a kettle you are performing a simple one-step process. When you use electricity to heat a kettle you are taking part in a complex multi-step process: burn fuel, change thermal energy to kinetic energy, change kinetic energy to electrical energy, change electrical energy to heat energy. Inevitably inefficiencies creep in and add up.

But wait, there’s more…

Before you all rush out to buy kettles for your gas hobs there a several things to bear in mind:

1. Gas is a natural resource – we will run out one day
2. Your electricity may be coming from an eco-friendly source – if you use electricity from wind/solar then you are probably being more green than using gas
3. Most modern electric kettles turn off once the water is boiled – most gas hobs do not, so you might use more energy because you don’t turn the hob off as soon as the water boils
4. The efficiency of electricity will hopefully increase in the future
5. If it is winter, the wasted heat of a gas kettle goes into keeping your house cosy and warm
6. There is an increase in the risk of fires if you heat water using the gas hob.

Conclusion – Gas or Electric?

It depends.

If you tend to turn the kettle on and come back in a few minutes when it has boiled then you are probably better off with an electric kettle as it won’t keep on heating the water once it is boiled.

If you are cooking with the water you are probably better off using the hob – you are only going to be heating the food anyway.

So, before you boil a kettle – take a second to think about how you are using it and whether you are going to stay next to the kettle then pick the most appropriate method!

References

1. Why thermal power plants have a relatively low efficiency
2. Energy Efficiency in Power Plants
3. Which Kettle to Choose: Gas or Electric
4. How to Boil Water

A common thinking is that if you want to be green you should only work for a green company. I am not convinced that this is the best philosophy if you care about making the world a better place.

If nobody green works at a non-green company then it may never improve

If all the people who care about improving the world avoid non-green companies then the following may happen:

1. All the non-green companies are staffed with people who don’t care about going green
2. As a result, there may be no internal push for the company going green
3. If the company does decide to go green (for financial gain) then they may go about it the wrong way – because nobody in the company cares or knows what being green means

If you care, try to change them

If you want a company to improve then you have two options:

1. Protest in some form – letters, boycott, etc.
2. Change them from within

I have a sneaking suspicion that companies are far more receptive of one of their own managers saying “hey, I think we should stop wasting all this energy” than someone sending in a letter. Also, more importantly, that manager (you!) can take ownership of the change and help it get done and get done right.