Australasian Science

Cars Are Doomed BY PATRICK MORIARTY and DAMON HONNERY

What are the options to turn around our transport and energy systems in time to meet long-term greenhouse targets?

he European Union is calling for a 2°C cap on allowable temperature increases, compared with the pre-industrial era, in order to avert dangerous “anthropogenic climate change”. The Intergovernmental Panel on Climate Change’s 2007 report is in accord with this limit, arguing that any higher temperatures would have serious adverse consequences. The problem is that we are nearly already at this limit. Today’s temperatures are already about 0.75°C above pre-industrial levels, and we are committed to a further 0.6–0.7°C due to thermal inertia in the climate system – even if we stopped

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all emissions tomorrow. Keeping within that 2°C limit will mean cutting present world emissions of greenhouse gases by as much as 85%, a 6.7-fold decrease. This decrease is similar to what Prof Ross Garnaut considered in his recently released interim report. A 6.7-fold reduction is a global average. Very high per capita emitters like Australia will have to cut emissions even more than the average. Our per capita emissions of greenhouse gases are about 4.5 times the world average, making us one of the highest emitters, and our transport/energy sector emissions are continuing to rise.

Under the “contraction and convergence” proposal, all countries would eventually move to the same per capita emissions, which would mean a 30-fold reduction in Australian emissions by 2050. By 2030, we might perhaps need to reduce this level by half – a 15-fold reduction. Of course, low-emitting developing countries would be allowed some increase, but they too must ultimately limit their emissions. What does this mean for transport? Greenhouse gas emissions can be quantified and compared in terms of grams of CO2 per passenger-kilometre (p-km). Presently the average Australian vehicle emits around 190 grams CO 2/p-km. Expressed another way, we get around 5.4 p-km per kg CO2. A 30-fold reduction would mean lifting the distance travelled to 160 pkm/kg CO 2 . This is equivalent to a passenger car fleet average of 260 km/litre of petrol, or around 0.4 litres/100 km. There’s a further problem. Petroleumderived fuels presently provide around 98% of the energy for the world’s transport. Like greenhouse gas emissions, oil consumption is very unevenly distributed among the world’s population, with Australian consumption per capita more than three times the world average. Only a limited number of approaches are available to “green” our present cardominated surface passenger transport systems. We can make use of more fuelefficient vehicles, improve their occupancy rates, or shift to low-carbon fuels, such as biomass or renewable electricity. We could, of course, adopt all these approaches. Remember, we will need to change very rapidly as time is running out to both limit climate change and respond to global and Australian oil depletion. The best way to improve fuel efficiency is to shift to hybrid electric vehicles like the Toyota Prius. Hybrids can improve fuel efficiency by up to 60%, with the greatest gains occurring in congested

urban traffic. By adopting hybrids, together with other improvements, the research literature suggests that we might be able to double the fuel efficiency of the car fleet by 2030, and perhaps quadruple it by 2050. Even this improvement would need extraordinary effort and political will. Car fuel efficiency today is no higher than it was 20 years ago. While we’ve improved engine efficiency, these gains have been undercut by larger and higher performance cars, and greater auxiliary power requirements such as power steering and air conditioning. Indeed, cars today are no more energy efficient than the T-model Ford was a century ago. Cars in Australia – and in high carownership countries generally – usually travel with 25–30% of seats occupied, and even less at peak hour. Couldn’t we rapidly cut both oil use and greenhouse gas emissions by improving occupancy rates? Experience shows that it’s difficult to even hold occupancy rates constant in the face of continued income rises, increasing car ownership and declining household sizes. Very extensive carpooling with non-family members would turn the car into a form of public transport, with destinations and timing of trips needing mutual agreement. This is not what most people think of when they think of private travel. And neither cars nor taxis are very efficient forms of public transport as they’re too small. Many argue that more use of liquid fuels from biomass sources can lower greenhouse gas emissions. But unlike wind power, for example, large-scale production of liquid fuels from biomass would compete with food production. Even if our entire food crop was used we would still not be able to make enough. Converting all of Australia’s grain, sugar and oilseed crops to liquid fuels would supply around 30% of the petrol and diesel energy we presently use, but what we presently eat we would have to import.

Larger supplies could come from cellulose feedstocks, but the conflict remains even if we do eventually work out how to economically make liquid fuels from wood because fertile, well-watered land is at a premium globally. Already, the world price of corn has risen because much of the US crop – the world’s largest – is diverted to “gasohol” for vehicles. “Plug-in” hybrid vehicles, in which the battery pack can be charged from mains electricity, are another possible solution but only if the electricity comes from lowcarbon sources. Unfortunately our actions on renewable electricity do not match our pious talk. Today the share of electricity produced from renewable energy

... cars today are no more energy efficient than the T-model Ford was a century ago. sources such as hydro, solar and wind is lower than in 1980, both worldwide and in Australia. True, electricity generated from both wind turbines and solar photovoltaic cells has been growing very rapidly, but hydroelectricity’s share – which still accounts for nearly all the world’s (and Australia’s) renewable energy electricity – has been falling. Can we turn our energ y system around? Two points are important in thinking about renewable energy electricity, for transport or energy generally. First, what is the potential for the various renewable energy sources? Some, like solar and to a lesser extent wind, are globally abundant, and Australia is wellendowed with both. Unfortunately there’s a catch: both wind and solar energy are intermittent energy sources and require expensive energy conversion and storage systems if they are to be our future energy mainstays. For other possible renewable energy sources, such as tidal, geothermal

energy and further additions to hydro, the potential is too small to ever be significant globally. The second important point is that we don’t have 50 years to re-fashion our entire energy system. Instead, we’ll have to do it in a couple of decades if we want to avert dangerous climate change. Energy supply systems change only slowly, mainly because of the huge investment in existing plant, such as fossil fuel power stations. Worldwide, hundreds of fossil fuel power stations are today under construction, with lives of up to 50 years. Not only developed countries but rapidly industrialising economies like China and India are being locked in to fossil fuels. To avoid the risk of adverse climate change, Australian transport may have to cut emissions 15-fold by 2030. If we’re lucky we might be able to double fuel efficiency and hold the line on further occupancy rate declines by then. And energy systems change too slowly for renewable energy to greatly increase its share by 2030. So we’re going to have to change our transport system. Australian public transport is roughly twice as energy efficient as car travel at present, and there is some scope for further improvement in efficiency. And it’s easy to improve occupancy rates when patronage is rising, as at present, by raising service frequency at a slower rate than patronage increases. Of course this leads to big efficiency gains – and over-crowding. But even if all Australian vehicular surface travel was by public transport we still couldn’t get anywhere near the 15fold cuts needed by 2030. Only reduced vehicular travel can do that. Our future cities will see a lot more active travel – walking and cycling – and a lot more emphasis on local activities. Dr Patrick Moriarty is Honorary Research Associate at Monash University’s Department of Mechanical Engineering, where Dr Damon Honnery is Associate Professor. Dr Moriarty would like to acknowledge the financial support of the Australasian Centre for the Governance and Management of Urban Transport (GAMUT) for the research reported in this paper.

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