Welcome to the eleventh post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. After our previous posts on hydro power, geothermal and wind (and a summary on the big three), solar, biofuels, marine and waste energy, we’re now looking at answering the question:
How can we achieve a BIG reduction in our personal and national energy consumption?
We covered the breakdown of where we use this energy in the last post. Today we’re dealing with our biggest chunk of energy use: road transport.
A few notes before we begin: as before, the units are in kWh/day/person – ie. if you ran a 40W lightbulb for 24 hours, it’d take ~1 kWh over the space of a day. We then divide it by person to give you a sense of the scale of the resource proportionate to the size of the population. Be sure to check out the methodology. For reference – we’ve been looking to replace around 55 kWh/d/p of energy currently generated by fossil fuels.
About a third (31kWh/d/p) of our total energy use is spent on vehicle travel, which is high by international standards. (This figure also includes some diesel purchases by small farmers and transport operators that are not adequately captured by other statistics.) Incidentally, one litre of petrol contains ~10kWh of energy, so at a national scale, we’re all using around 3 litres of petrol/person/day. By comparison, the average UK citizen spends 14 – 16kWh/d/p on personal vehicle travel. Consider that the average NZ car drives 18,000km in a year. If all were medium SUVs (0.9kWh/km) with 2 people in them, then this would translate into only 22kWh/d/p. It is clear then that we must make a lot of single-passenger trips in inefficient vehicles. Worse, this works out at a staggering 46kWh/d per vehicle (excluding mopeds, but including trucks)!
If spending on vehicle fuel is our largest energy use, how much scope is there for improvement? MacKay proposes that UK energy expenditure could be halved by electrification of transport, better cycle access and good public transport. Our low population density will limit the effectiveness of public transport and while we’ve made a bit of progress on building bicycle infrastructure, our focus is still heavily on vehicle infrastructure making bike-use less attractive.. We must surely be able to waste less than we do at the moment.
Electrification of Vehicles
McKay makes a strong case for the electrification of personal transport. Electric cars are 3 times more efficient at turning energy into motion than petrol motors, even when accounting for battery losses and transmission losses. When compared to other post-oil fuel sources (hydrogen, natural gas, biofuels, hybrids etc.) the benefits of electric far outweigh the negatives, and offer the ‘path of least resistance’ to uptake.
Most vehicle manufacturers have now recognised that electric is the way of the future and GM, Ford, BMW, Audi, Renault/Nissan and most other major car manufacturers are now intensely developing the technology and beginning limited production. Since 2009, the ‘race’ over the technology that will replace vehicle propulsion has been won by electric. However, the timeframe for the scale up is long, as it takes 20-30 years to replace the rolling stock from the point where they become the predominant technology.
Regarding the transition in New Zealand, it is likely that we will see greater adoption of electric cars as they become more economic. Currently the sticker price of electric cars is significantly higher than comparable models. This is primarily due the battery, which at half the cost of production is the single most expensive part of the car. We can expect this to come down over time.
The other relevant factor to consider is the impact of ‘range anxiety’ – electric cars have limited ranges compared to petrol cars which can just be quickly refuelled, and this is a concern of a lot of buyers. NZer’s drive on average 50km a day, which is less than half the range of most electric cars on the market. For everyday use, electric can suffice. For longer trips – technology is improving all the time, and most electric cars now come with a ‘fast charge’ option that gets up to 80% of the charge within the first few hours. Tesla Motors has just announced new charging stations that can give three hours of driving after 30 minutes of charging. This is a fast developing area of technology. The other alternative is to rent a petrol car for longer trips.
In regards to the impact of electrifying transport on the grid, Transpower’s Centre for Advanced Engineering has conducted studies to assess viability and how much, if any, new generation capacity would need to be built. They concluded that even in the ‘high uptake electric vehicle scenario which sees over 390,000 electric vehicles on New Zealand roads by 2025, a maximum of only 180 MW of additional generation capacity would be needed – that’s the size of two medium sized wind farms such as ‘West Wind’. Further, the majority of the energy used for recharging would be at night when the grid is at its lowest and electricity is at its cheapest. The current wiring set ups in NZ households are capable of handling basic charging, but would need modification if they were to handle high voltage charging stations. [9x97yvx]
Like McKay in the UK, we think the case for the gradual electrification of New Zealand’s transport networks is strong, but will depend on the developments of car manufacturers overseas bringing down the costs, the relative costs of other transportation and the business models that can be developed for a New Zealand context that can drive adoption.
The case for bicycles
Bicycles use only 1kWh/100km, or roughly 1/100 the energy a car uses [95nwj67]. McKay is a big fan of biking for its energy intensity and related health benefits. It is easy to imagine that NZ, with its outdoorsy lifestyle and temperate climate would be an excellent country in which to encourage more use of biking.
What are the things that we can do to encourage a greater uptake of bikes? A Rutgers University study of biking patterns in 100 US cities has shown that there is a strong correlation between the number of bike kilometres travelled and the level of bike infrastructure present (bike paths/bike stands etc.) [8597ys8]. A Ministry of Transport study has similar conclusions [9xghegt].
McKay makes a big case for the development of bike-friendly infrastructure and legislation, in the form of separate bike lanes, lower speed limits and collision regulations that favour cyclists. If we’re going to increase biking as a viable transport option in NZ, we will need to take cycle infrastructure investment more seriously than we do today.
Improving our current vehicle options
When considering a car purchase, there are alternative strategies that can improve energy use. For example it has been noted that people tend to buy the car they want to use for holidays – and then commute in it. How about if we bought an efficient commuter vehicle and just hired an SUV for 3 weeks of holiday? According to the AA vehicle running costs report (AA members only, sorry), it works out something like this:
|Small car (1200cc)||Medium||Diesel SUV|
|Annual running costs||$7300||$11,100||$14,000|
Three weeks hire on a Prado or Pajero would cost around $3000 plus fuel while a small SUV would be $2000. The philosophy of “commute in small and hire big when required” saves money as well as energy.
Being very optimistic, let’s suppose that we can get energy use from car travel down to 15-18kWh/d/p by savings and improved technology by around 2030, a saving of 13-16kWh/d/p.
Q. Should I telecommute when that means heating my otherwise empty house, when I could drive to work and use their heating system instead?
A. If you work for 8 hours at home crouched over your one bar heater, you use 8kWh of heating. You spend the same energy driving 13km in a Yaris or 9km in a RAV. If it works for you, then telecommuting is a good option energy-wise.
Q. How much fuel do I save if I travel slower?
A. See MacKay’s book for a detailed analysis, but considering air resistance only, fuel usage is proportional to square of speed. I.e. if you went half as fast, you would use a quarter of the fuel. In real-world performance, cars have rolling resistance. Most engines are tuned for an optimal revolution speed and gearing is designed for current road speeds. Nonetheless, travelling at 80kph instead of 100kph could deliver up to 30% fuel saving.
We’ll be looking a bit more into the costs of the electrification of transport at the end when we propose a plan using the different things we’ve talked about in this series.
Tom Murphy at Do The Math has a number of articles on the electrification of transport, starting with a calculation of the MPG of electric cars, assessing whether a solar powered car is a feasible option, doing the math on whether 100MPG is even possible, and assessing where it is that we can all reduce our liquid fuel use. He also has a great article on the limitations of battery development for electric cars – they’re hard to build, and they’re not developing at anywhere near the speed of computer chips. That last one is a sobering reminder of the fact that new technologies sometimes take longer than we would like to develop.