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Melbourne Transport |
Common Urban Myths About TransportMyth:
Alternative fuels will come to the rescue
Fact:
Many alternative fuels do nothing to fix local air pollution, merely
substituting one noxious chemical for another. Others such as natural
gas or ethanol are impossible to produce on the scale required. This
leaves electricity and hydrogen, but as these are energy carriers rather
than fuels they must themselves be produced using some other fuel, which
just pushes the problem up one level. Public transport meanwhile has a
fraction of the emissions of car transport even with current fuels.
The road lobby itself never denies that cars do a lot of damage to the environment through the pollution and carbon dioxide they generate. But they tell us not to worry, because we are only a few years away from technological solutions that will make cars truly environmentally friendly. Next to the usual fairy tales about improving fuel efficiency, their favourite argument is that new 'green' fuels, already under development, will replace petrol and render pollution and greenhouse emissions a thing of the past. A Fuel's ParadiseThe quixotic quest for the new miracle fuel that will surpass petrol, and be cheap and plentiful to boot, has been with us for at least half a century. In the 1950s, cars powered by personal nuclear reactors capable of travelling thousands of kilometres on a handful of uranium were supposed to be on the verge of becoming a reality. In the 1970s solar cars were just around the corner, and in the 1990s the next big thing was running cars on used cooking oil - assuming you could get it in the quantity required. Still no challenger has risen with serious prospects of toppling the dominance of petrol and diesel. On the margins, LPG conversions are becoming popular as a way to avoid high petrol prices (and got a boost courtesy of the former Howard Government), but the efficiency benefits should not be overstated: as the following table shows, the average LPG-fuelled car has only about 3 per cent less CO2 emissions than the average petrol-fuelled car, and is slightly less energy efficient.
Source: Australian Greenhouse Office. Australian Methodology for the Estimation of Greenhouse Emissions and Sinks 2002. Fuel consumption figures are based on fleet averages. Emissions from the fuel supply chain are excluded. But even if the new miracle fuel became available tomorrow, along with cars capable of running on it, it would still take many years before most vehicles on the road used the new fuel. This was seen with the introduction of unleaded petrol in 1986; after 15 years there were still many pre-1986 vehicles on the road, hence the need to distribute 'lead replacement' petrol extensively when leaded petrol was finally phased out. And this was a relatively minor technology shift, so the technology could be made available in all new vehicles from 1986 onward for very little additional cost. Changing to an entirely new fuel source is a much larger technological leap, so even when new fuel technology becomes commercially viable it will take some time before it accounts for even a significant minority of new vehicle sales. Thus, while cars with hybrid petrol/electric engines have been on the market now for some years, their higher price tag and doubts about their performance have kept their market share low.
Substituting One Problem For AnotherThe real difficulty with alternative fuels is, however, the same as with any attempt to treat the symptoms instead of the cause of a problem: the fundamental problem doesn't go away but instead lingers to cause more difficulties later on. Any hydrocarbon fuel when burnt in air, whether it be petrol, diesel, biodiesel, LPG or ethanol, produces both carbon dioxide and noxious byproducts such as nitrogen oxides and ozone. Of course they differ in degree: diesel and biodiesel produce lower sulphur emissions than petrol, but produce more particulate matter (soot) which is associated with higher rates of lung disease; ethanol may or may not reduce net carbon dioxide emissions (depending on where it comes from) but increases emissions of ozone and of formaldehyde, a highly toxic organic solvent. Even the lowest-emission fuels, LPG and natural gas, can often produce as much or more carbon monoxide and nitrogen oxides than petrol (and are also much more limited in supply). And just as with the claim that free-flowing traffic cuts pollution, any overall reduction in pollutants is soon cancelled out by the sheer growth in car and truck trips. The only 'fuels' that do not produce local pollution are electricity and hydrogen. But these are not fuels so much as energy carriers; they do not occur naturally but instead must be generated from some other, naturally-occurring energy source. In practice electricity in Australia will continue to be sourced mainly from coal for a while yet, while hydrogen is today most commonly produced by 'steam reforming' of hydrocarbons, which generates carbon dioxide as a byproduct. As a result, use of electric or hydrogen-powered cars will not reduce greenhouse emissions, and may even increase them. Think of it this way: the most efficient electric car imaginable is no more or less 'green' than an air-conditioner you run every day of the year. This follows from simple arithmetic. State-of-the-art electric vehicles (such as this one produced by volunteers at CERES in Melbourne) achieve an efficiency of about 150 watt-hours per kilometre: a figure that's unlikely to be improved upon with anything that looks like a motor car, since electric technology is now quite mature and the motors in these cars already achieve up to 95% efficiency. But a car in Australia is driven on average 40km every day (15,000km a year) which means the electric car requires 6kWh of electricity per day to run with typical usage patterns - equivalent to two hours a day of full duty for a 3kW air conditioner. (And that's for an efficient vehicle: conventional sedans under similar assumptions run the 'virtual air conditioner' for 6 hours each day, summer or winter!) Promoters of these vehicles quite correctly point out that they produce zero emissions if they run on renewable electricity. And doubtless something very like this will wind up being the future of motoring. But we must also realise that the exact same claims being made for these vehicles are equally true of air conditioners, plasma TVs or any other energy-hogging appliance. If a carbon-constrained world requires us to moderate our use of plasma TVs, it likewise requires us to moderate our car travel. And while it is possible to imagine that at some time in the future we may be able to use electricity derived mainly from wind farms, hot rocks or massive solar collectors in the desert, it is unlikely to be cheap or plentiful enough by itself to sustain modern travel habits as well as our demand for electricity. Hydrogen faces a similar problem. The only known carbon-free way to produce hydrogen in quantity is using renewable electricity, and so no technology based on hydrogen fuel cells is going to be significantly more efficient than one using electricity; it comes down to comparing the losses in a hydrogen supply chain with those in electricity transmission, which are about the same in any case. And if the electricity isn't renewable, then neither is the hydrogen.
These same caveats apply also to more exotic, enthusiastically promoted alternatives such as compressed air, flywheels and hydraulic fluid. The energy always has to come from somewhere, and the available sources are either expensive, scarce or environmentally damaging. For example, though compressed air is commonly regarded as a 'free' energy source (it's just air!), most air compressors are only 10 to 20 per cent efficient, losing the bulk of their energy input as heat or through leakage. So every unit of energy stored in compressed air has required another 4 to 5 units just to produce. It also has to be remembered that even pollution-free cars and trucks would still crash just as often, take up just as much land for roads, and generate the same equity problems as they do today. There truly is no 'free lunch' when it comes to solving the problems with car transport; instead there is an unavoidable imperative to use cars less and travel more by public transport, by bike or on foot.
Petrol From Coal?One of the scarier suggestions to emerge from the fuel price hikes since 2005 is that we hasten climate change by using liquefied coal as a replacement for petrol and diesel. Although this is feasible with current technology (indeed, the Germans did it during both World Wars), it is still too inefficient and expensive to be commercially attractive. And because to liquefy coal one essentially has to remove the 'excess' carbon from it, thereby generating carbon dioxide, we would actually wind up generating CO2 even faster than we currently do by pumping oil and burning it in car engines. According to industry figures obtained by the University of Technology, Sydney, the use of liquid fuel derived from Victorian brown coal would generate more than double the greenhouse emissions of ordinary petrol (182g CO2/MJ compared with 84g CO2/MJ). The liquefication plant alone would have eight times the emissions of a conventional oil refinery. This would be a huge backward step in the search for sustainable energy. Nonetheless, the very same Victorian Government that refuses to spend money on new rail extensions has been backing a $5 billion project to convert coal into transport fuel. The success of the project relies on being able to pump the excess CO2 underground, an unproven technique that so far no-one has got to work reliably despite all the breathless PR that has been devoted to it:
Alas for all that misplaced government investment, the Monash Energy project was shelved in December 2008, less than two years after commencing.
The Biofuel Red HerringFinally there are the now vigorously-promoted schemes to actually 'grow' the fuel for our cars by planting crops, digesting the crops to produce biofuel, running cars with the biofuel and using the carbon dioxide emissions to grow a new crop. While superficially attractive, these schemes suffer from the same problem as schemes to plant trees to soak up carbon emissions: the sheer scale of our driving habits makes them unviable. Converting the entire Australian wheat crop to ethanol production would, for example, only substitute for around 15% of Australia's oil consumption. There are many similar findings:
Biofuel schemes, then, can only possibly work in conjunction with policies to substitute environmentally friendly transport for car and truck trips. Meanwhile there are increasing doubts whether the production and use of biofuels really has a net positive greenhouse impact at all. Although it seems obvious that biofuel crops should soak up roughly the same amount of carbon dioxide when growing that they give off when burned, there are other factors that intrude on the process. The biggest of these is that the crops rely on fertilisers that produce significant emissions of nitrous oxide (N2O), a greenhouse gas 300 times as potent as carbon dioxide. A 2007 paper by Nobel laureate Paul Crutzen concludes that biofuel crops can cause as much global warming via N2O as they save in CO2 from displaced fossil fuels.
Then, there is the tendency for biofuel crops to be grown on cleared peatland or rainforest land in countries like Indonesia or Brazil. Clearing a rainforest removes a carbon sink more significant than a biofuel crop, while draining a peatland releases enormous quantities of stored CO2. Together, all these effects wipe out the emission savings from use of the harvested biofuel. According to two studies independently published in the journal Science in February 2008, and a third study in October 2009, almost all current biofuel production is causing more greenhouse emissions than conventional fuel use. A related article points out that the failure to account for this kind of land use change counts as a critical error in carbon accounting under the Kyoto Protocol (which also forms the basis for Europe's emissions trading scheme). Biofuels also suffer from other more practical problems. One such problem is their limited shelf life - as short as two weeks in ethanol's case, or around three months for biodiesel. While ordinary petrol or diesel can sit unused in a fuel tank for long periods, current biofuels will degrade, and this can result in engine damage. For this reason, owners of recreational boats (which are used only seasonally) are advised against using biofuels or biofuel blends. The same advice might apply to car owners who use their cars rarely. Last but not least there is the rather nasty side-effect, that using 'energy crops' for fuel competes directly with food supplies. The Earth Policy Institute in the US estimates that the grain required to fill one 25 gallon (95 litre) fuel tank would feed one person for a year. The US already uses nearly one-sixth of its grain crop (and over half of all its corn) to produce ethanol for cars, and while this represents only 3% of all fuel sold, it is starting to affect the global prices of wheat and corn, which feed into other food prices. (The price of one corn variety increased 45% in 2006 alone.) Brazil meanwhile uses its extensive sugar cane crops to make ethanol (much of them on cleared Amazon rainforest), and this has been a factor in the world price of sugar trebling between 2004 and 2006. According to a paper in the Proceedings of the National Academy of Sciences in the USA, it would be impossible for ethanol to significantly replace petroleum without a serious impact on food supplies.
In the 1850s, the great Irish Potato Famine resulted when wealthy consumers bid up the price of scarce potatoes, so that poor people could no longer afford to eat. A similar threat exists to those in developing countries today if ethanol and biodiesel become significant fuel sources for affluent motorists. This is not just alarmist speculation: in all but one year this century the world's consumption of wheat has exceeded production, and in 2007 global wheat stocks were at their lowest level since 1972. According to New Scientist in April 2007, industry insiders are concerned about the recent emergence of new resistant varieties of old crop diseases like black stem rust; meanwhile, Australia's own wheat production is threatened by drought. We cannot be complacent any longer about the world's capacity to produce staple crops.
Further confirmation has come from the OECD (hardly the world's most ardent greenies) who in 2007 weighed in with its own assessment, stating in its own way the same conclusions drawn by others.
Most recently, a study by the World Bank reported in the Guardian on 4 July 2008 confirmed that biofuels were responsible for 75% out of the 140% rise in global food prices since 2002, and that these price rises have pushed 100 million people below the poverty line in that time. The Celsias Blog has compiled a useful round-up of the evidence on unintended consequences of biofuel promotion. ConclusionIn its investigation of all the options, the British Royal Commission on Environmental Pollution concluded that
The same conclusion was reached by technology experts at MIT, in a 2008 assessment of emerging technologies:
And even the economically-dry OECD concurs, even going as far as to say it is more important to reduce demand for fuel instead:
There is certainly a limited role for some alternative fuels in particular contexts; Paul Mees notes in A Very Public Solution that use of compressed natural gas instead of diesel in vehicles that stop frequently in urban areas, such as buses and garbage trucks, would help put these essential services on a more sustainable footing. (Though even here caution is required: the spark-ignition engines that burn gaseous fuels are less efficient than diesel engines.) But public transport already has the advantage here: even run using coal-fired electricity and diesel fuel as at present, well-run and well-used public transport has energy use and emissions per passenger that are a fraction of those from present-day cars, and much less than those even from the most efficient electric cars now available. In the final analysis, the use of alternative fuels will have at best a marginal benefit, and will have no benefit at all unless accompanied by a substantial switch from car trips to public transport, walking and cycling.
© 2010 Public Transport Users Association Inc. (PTUA), Victoria, Australia. ABN 83 801 487 611. Last modified: 23 February 2010
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