Tuesday, February 06, 2007

Why the Dust to Dust Report belongs in the Dustbin

We have received a lot of emails lately from disgruntled 4x4 owners and piston heads who have been claiming that their 4x4 is better for the environment than a new hybrid car. Their information, we assume, comes from an article printed last year in a car magazine. We wish to inform them that the “Dust to Dust” report by the Seattle-based marketing company, CNW Marketing Research, is fundamentally flawed. We have consulted friends in the field and they have suggested the following points to support this assertion.

On the face of it, the report appears to be an extensively researched study, all 450+ pages; however it quickly becomes apparent that it provides no evidence whatsoever to back up its assertions. They claim to have nearly 4,000 data points on each of more than 300 models of vehicle. However, none of this data is actually included in the report, and there are no referenced sources, making it impossible to judge the quality of the data used.

Another big problem with the report is its lack of logic. Its main argument is that a fuel-efficient hybrid car (say 45mpg) uses more energy in its lifetime than an inefficient 4x4 (say 22mpg), because, the energy required to manufacture the hybrid outweighs the fuel saved when it is being used. It is valid to say that it takes more energy to manufacture hybrid cars. This is because of the advanced motor and battery technologies used, and the higher energy requirement of materials such as aluminium and lightweight steel.

However, the higher energy use at the manufacturing stage is more than compensated for by the energy saved when the car is being used. Reputable, peer-reviewed studies have concluded that between 10% and 30% of the total CO2 emitted by a car during its life-cycle come from the manufacturing and disposal phase, and at least 70% of CO2 comes through the use phase (i.e. when the car is actually being driven). A list of legitimate life-cycle studies is included below.

Simply put, there is no possible way that a 45mpg car could use more energy than a 22 mpg car provided they both have reasonably similar amounts of use. The only way that CNW could possibly argue that the hybrid uses more energy in its lifetime would be to assume that hybrids drive a lot more miles than less efficient cars. However, bizarrely, in their report CNW actually claim that gas-guzzlers drive more miles than hybrids! (For example, CNW claim that the gas-guzzling Hummer H3 drives 207,000 miles in its lifetime, while the Toyota Prius drives 109,000 miles.)

No reason is given for this assumption over mileage, but there is no technical reason why it should be the case: In California, the Prius hybrid system components are warranted for 150,000 miles. The point however is that if a Hummer H3 were to be driven twice as far as a Prius, then it would use vastly more fuel; far more than enough to overtake any additional energy used in the manufacture of the Prius. Yet CNW still claim that the Prius costs more in energy terms per mile than the Hummer.

The report also makes a fatal mistake by attributing all of the design and development energy costs to the existing range of hybrids. Art Spinella, the author of the report has admitted in an interview that if the study were repeated in 3 years time, the results would be “totally different”.

A quick example illustrates the flawed reasoning used in this report: the energy cost per mile of the Volkswagen Golf is given as $2.70 while that of the Hummer H3 is $1,95. How a car, with no special hardware, greater than twice the fuel economy and less than half the weight of the H3 can consume nearly 40% more energy every mile is not explained.

These are but a few illustrations of where this so-called 'study' is flawed, but the points outlined above are the most notable. The CNW report can be considered in the same category as 'modern research' published to throw doubt into the debate on the science of climate change, and should be treated with extreme scepticism by any well-meaning person.

Here’s a list of credible Automotive Life Cycle Studies:

• A report produced by Transport Research Ltd “Sustainable resource use in the motor industry: a mass balance approach”, 2004, concluded that about 80% of the total CO2 emissions from a car are as a result of its use, and 20% as a result of its manufacture and disposal. The report was produced by Transport Research Ltd under part of a contract by Viridis and is available from TRL publications publications@trl.co.uk.

• Data provided from Toyota’s Environmental and Social Report, 2004, states that 15% of CO2 comes from material manufacturing, 5% from vehicle manufacturing, 75% from use and the final 5% from maintenance and disposal. In 2002 EUCAR ran a project called LIRECAR to study lifecycle emissions of lightweight vehicles with the inclusion of a regular vehicle as a baseline. The average figure was 90% of the emissions produced in the use phase and 10% during production.

• The UK Low Carbon Vehicle Partnership, who undertook a literature review and consultation on this issue in 2005, concluded that around 80% of a vehicle’s CO2 emissions come from the usage phase (plus-minus 10%)

• Volkswagen life cycle analysis of a Golf mark 3 suggests that some 70 to 73 per cent of energy is consumed during the use phase, Schweimer and Levin Life cycle inventory for the Golf (2000). This study includes reference to energy to produce the fuel, emphasising the use phase.

• CO2 analysis work by Dr. Ben Lane for Camden Council (2006) on fuels and production emissions suggests higher emissions in fuel production, but similar emissions from vehicle production and use to that outlined by Schweimer and Levin

• A breakdown of the three life cycle phases, based on Lirecar (2004) (5) suggests that five percent of energy is consumed in disposal Life Cycle Assessment of Lightweight and End-of-Life Scenarios for Generic Compact Class Passenger Vehicles Wulf-Peter Schmidt, Elisabeth Dahlqvist, Matthias Finkbeiner, Stephan Krinke, Silvia Lazzari, Dirk Oschmann, Sophie Pichon and Christian Thiel (2004)

• Taking all these studies into account, the SMMT (the UK auto industry trade body) estimated in their most recent sustainability report that for a mid range car, used in the United Kingdom they suggest life cycle and CO2 can be allocated in the following way: Manufacturing 10 per cent; Use 85 per cent; and Disposal 5 per cent.