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Production emits more CO2 than most carmakers admit, but its true share of a vehicle’s carbon footprint is being tackled. Susan Brown reports

Conventional wisdom states that most CO2 is generated during a vehicle’s use and that, in comparison, the contribution of manufacturing is negligible, at around 5 to 10 per cent of its total lifetime emissions. In fact, the real figure is much higher, but manufacturers tend only to report emissions from their own plants, excluding those from component and material suppliers and during transportation.

“Vehicle manufacturers report an average of 0.6 tonnes per vehicle of CO2 generated from manufacturing,” says Simon Barnes, environmental affairs manager at UK auto industry body the SMMT. “But we need to at least treble this figure to take into account component and material manufacture.”

This still creates less than two tonnes, while an average vehicle producing an average 167g/km of CO2, driven for 15,000km a year over 10 years would generate about 25 tonnes. Barnes says the contribution of transport in the supply chain is a relatively small contributor to CO2 emissions, although it is difficult to obtain accurate figures.

But some research puts manufacturing’s contribution to lifecycle CO2 emissions much higher. Renault estimates that about six tonnes of CO2 is emitted by assembly plants, suppliers and supply chain distributors to manufacture a car.

“Our figure includes the transport emissions from the supplier to the assembly plant, supplier material and energy usage,” says Renault. “Our suppliers represent a 75 per cent share of vehicle production CO2 emissions.”

Based on average annual mileage of 15,000km, an average Renault will produce some 2.4 tonnes a year of CO2. So, during a typical lifetime of 10 years, it will produce 24 tonnes and the six tonnes generated in its production is a fifth of its lifetime emissions. That’s worth considering.

Recent lifecycle analysis on the Mercedes-Benz C-Class found that over 84 per cent of total CO2 emissions came from the use of the car. But this analysis was based on a lifetime covering 200,000km. If that figure was considered to be 150,000km, the CO2 from manufacture would account for closer to 20 per cent of lifetime emissions.

Renault’s estimate is its response to the Carbon Disclosure Project, a coalition of institutional investors representing more than $31 trillion in assets, which annually requests information from large multinational companies about their climate-risk position. The project asks companies to disclose much more information about their greenhouse gas emissions than they would otherwise provide.

A close look at other vehicle manufacturers’ responses makes it clear that they do not consider all the emissions generated during manufacture.

In its environmental report, Volkswagen only reports emissions from power generated on site. It omits bought-in electricity because of different standards for calculating greenhouse gas emissions.

Detailed product lifecycle analysis is scarce in the public domain, but where it is available it provides a lot more detail on CO2 emissions throughout the production process, as well as during the use of the car. Such analysis for the Golf IV shows that, in 1999, VW generated 1.89 tonnes of CO2 for each unit produced. The supply chain pumped out a further 2.5 tonnes.

Manufacturing the car in its entirety therefore produced about 4.4 tonnes – almost 15 per cent of the lifetime total of 30 tonnes.

But in the VW’s 2005 sustainability report, it gives only its in-house CO2 figure. Divide this by the number of vehicles produced and it appears that each car coming off the line is responsible for just 0.26 tonnes.

It’s easy for the figures to be a little misleading, but if OEMs are to reduce their effect on the environment or at least raise the level of the current debate, they need to offer better disclosure to make figures easier to compare. But it is important to stress that other manufacturing industries don’t do anything like this. It seems a little unfair to expect the OEM to control second and third-tier suppliers.

Some manufacturers already have targets to reduce greenhouse gas emissions from production. GM recently announced a target CO2 reduction of 40 per cent from its plants between 2000 and 2010. In 2000, it produced 13.58 million tonnes globally. In 2005, it had reduced this to 13 million tonnes.

By 2010, Nissan aims to reduce manufacturing CO2 emissions at its main factories by 7 per cent per unit from 2005 levels of 2.31 million tonnes.

Toyota is aiming to reduce CO2 emissions worldwide by 20 per cent between 2001– when it produced 5.9m tonnes – and 2010. But by 2004 the figure had risen to 6.4m tonnes because of increased production.

Renault is aiming for a consistent 2.5 per cent per year reduction.

So far, Volvo Trucks is the only OEM intending to become carbon neutral. It is aiming for carbon-free manufacturing at its three European assembly plants by investing in biomass and wind, but it admits this only covers a fraction of total greenhouse gas emissions during manufacture.

Ford aims to have one “reasonable” renewable energy scheme for each of its plants in Europe. The technology varies from factory to factory. It already uses wind power at its Dagenham, UK site and is planning another turbine for Genk in Belgium, along with land leasing for solar generation. A planned biomass generator scheme is on hold because of financial constraints.

Ford is part of Europe’s emissions trading scheme and this has helped focus efforts on CO2 reduction, but the company admits the price is low and it has some carbon credits, so there is little urgency for change.

PSA, DaimlerChrysler and BMW say they will announce CO2 reduction targets in the near future.

Lifecycle analysis is becoming an increasingly important area of study for vehicle manufacturers, and it is an area in which they can take the initiative, according to Ian Kershaw, who leads Ricardo Strategic Consulting. “If people want to make an informed choice about the environmental impact of the vehicle they buy, they will want to know the energy consumed at all stages of a vehicle’s life.”

In particular, lifecycle analysis is expected to be used to assess the overall impact of switching to alternative fuels and in the choice of production materials. Aluminium, for example, as a lightweight material can reduce fuel consumption, but is very energy intensive to produce. Taken over its entire lifecycle, a steel component can produce less CO2.

Manufacturers need to understand the true environmental cost and be able to explain this fully to legislators, says Kershaw.
As vehicle manufacturers become more successful in driving down tail-pipe emissions, the proportion of greenhouse gases produced during manufacture is likely to become more important. If its efficiency improves, its contribution to lifetime CO2 emissions may stay broadly similar; if it doesn’t, there may be an environmental advantage in driving old cars for longer, rather than generating several tonnes of CO2 to manufacture a new one.

One thing is clear, however: energy, cost and CO2 are inextricably linked and a more holistic approach is needed.