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Around half of all car trips in Australian cities are for distances less than five kilometres; a third of car trips are for distances of less than three kilometres. It’s a telling reflection of just how far our reliance on cars extends. Once a symbol of freedom and mastery over distance, the automobile has since become an essential part of daily life for many, and, in turn, a major contributor to climate change. Emissions from passenger cars account for eight per cent of national greenhouse gas emissions.
But as petrol prices climb ever higher and sustainability becomes a selling point, car manufacturers are responding by marketing so-called green vehicles. The ‘green’ label is typically applied to petrol cars with lower fuel consumption and cars that run on alternative fuels, from biodiesel to electricity. We take a drive through the ever-changing market and cast a critical eye over the eco-credentials of today’s green fleet.
Currently one of the most economical sources of power, and particularly ingrained into our lifestyles, oil (petroleum) accounts for 43.4 per cent of total world energy consumption. This non-renewable resource is also the predominant fuel used to power our cars.
If carbon dioxide emissions are used as the sole point of comparison to determine how green a car is, then it is certainly true that the lower the petrol consumption, the lower the carbon dioxide emissions, therefore, the ‘greener’ the vehicle. Simple yes, but not technically ‘green’ at the same time – if we were to use that sensibility then nuclear powered cars would be green too.
Choosing a car purely based on low fuel consumption is certainly a greener option however than the array of fuel-guzzlers that clog our country’s roads. If you’re looking to purchase a car based purely on low fuel consumption, take heed of the advice of Andrew Ellis from Suzuki Australia: “We believe a green car should have fuel consumption of no more than 6 L per 100 km and have high levels of recyclability.” As such, many small petrol-powered vehicles are often viewed and touted as green, purely for their low fuel consumption.
However, greenhouse gas emissions from the tailpipe don’t tell the whole story. The sourcing of materials, production of the vehicle body, distribution methods and recyclability also affect GHG emissions. And exhaust fumes from petrol vehicles contain many other pollutants: carbon monoxide, soot and hydrocarbons.
■ Whats all the fuss about hybrids?
The most common type of hybrid car uses a conventional in-line petrol combustion engine as its primary energy source and an electric motor, with lithium battery storage, as its secondary energy source. When the first-generation Toyota Prius became available in 2001, it was the first mass-produced hybrid vehicle and the eco car du jour. So has anything really changed? Due to the current downsides, and delay in introducing other alternatives or infrastructure to support other alternatives such as electric vehicles, hybrids presently tend to be the most economically-feasible and convenient eco-vehicle on the market.
■ Liquid petroleum gas (LPG)
It’s been around for decades and fuels our taxis and buses, but LPG may be a good idea for cars, too. Made from a mix of mostly propane and butane (it differs from BBQ fuel which is pure propane), LPG is stored as a compact liquid and converts to a dry gas vapour when burnt during use. Though it boasts lower CO2 emissions per litre than both petrol and diesel (1.6 kg per L) and burns a lot cleaner, emitting only CO2 and water without additional greenhouse gases, it also has a lower energy content, making LPG-powered vehicles less fuel-efficient than their petrol and diesel counterparts.
However, depending on the vehicle, total emissions can still work out to be less than that of petroleum fuels. It’s possible to convert any car engine to run on gas. The modification costs around $2,500-$4,500 but you can claim a $1,250 rebate (which will drop to $1,000 on 1 July 2012) from the federal government. A $2,000 grant is available for anyone purchasing a new LPG vehicle.
■ Is diesel really better than petrol?
With a long-held rep of dirty trucker fuel, diesel has seen a complete overhaul in recent years in perception and use, with more and more smaller passenger cars using it. Diesel is produced from the same process as petrol, however, its density is higher than petrol and so it provides about 12 per cent more energy per quantity. Although diesel releases more greenhouse gases per litre than petrol (2.7 kg vs 2.3 kg), a diesel car is typically 20-30 per cent more fuel-efficient than a comparative petrol car. For this reason, the CO2 emissions of diesel vehicles tend to be lower overall.
Diesel models usually carry a premium of about $2,000 for a new car, and though it used to be more expensive to fill up at the pump, the scales have tipped in recent years, with prices on a par with petrol.
■ What’s the deal with ethanol and other biofuels?
Bioethanol (commonly known as ethanol) is made from the same fermentation process of starches and corn that is known all too well to the makers of moonshine. In other words, it is pure alcohol.
With one litre of petrol estimated to produce 2.33 kg of CO2, Australia emits around 44 million tonnes of CO2 per year through petrol-fuelled vehicles. One litre of pure ethanol is estimated to save 90 per cent of emissions, emitting just 0.22 kg.
E10, a petrol blend containing 10 per cent ethanol, is widely available at petrol stations around Australia. Some car makers are currently working to modify engines that are compatible with blends of 85 per cent ethanol, a move that would save around 30 million tonnes of CO2 each year were all cars to use it.
The potential problem with biofuels lie in their ingredients – that being they clash with food production, raising food prices. In the US, biofuels are commonly made from one of their most commonly used grains: corn. Recently, the World Trade Organisation (WTO) called for an end to subsidies for bioethanol production on the grounds that it was forcing up food prices and that the industry encouraged deforestation to make way for biofuel crops. According to the Biofuels Association of Australia, our ethanol is mainly made from sugar
cane waste, starch waste and red sorghum, so there is little conflict with food production.
Rudolf Diesel, the inventor of the diesel engine, also invented an engine that runs on peanut and vegetable oil in the late 1800s. Biodiesel is an alternative fuel produced primarily from vegetable oils, animal fats and waste cooking oil. It can be blended with conventional diesel in a similar way that ethanol is with petrol. Biodiesel blends are available as B5 and B20 from an increasing number of service stations. The industry is currently looking into new high-yielding oil crops such as algae, which can produce 100,000 litres of oil per hectare, as future biofuel sources.
■ Hot for hydrogen?
Hydrogen has been put forward as a promising replacement for fossil fuels since the 1970s. Hydrogen is not an energy source, but an energy carrier because it takes a great deal of energy to extract it from water.
Hydrogen’s potential for vehicles has not been realised mostly due to storage and commercial production difficulties. Hydrogen fuel stations are necessary to refuel a fuel cell vehicle and, as it stands now, these stations are limited in numbers.
Mercedes-Benz are pushing hydrogen cell technology more than most, with their F-Cell technology prompting the building of an extra 20 hydrogen refuelling stations throughout Germany, adding to the 30 that are already in operation.
In 2008, Honda released the FCX Clarity, the first hydrogen-powered car for general consumers, which could be refilled via a petrol pump-style hydrogen station, and Toyota recently opened the first hydrogen fuelling station in the US with hydrogen supplied directly from a pipeline rather than tanks.
Toyota has announced plans to bring a hydrogen fuel-cell vehicle to the US market by 2015, although there is no news yet of an Australian launch.