Reduce energy usage and it follows that emissions will fall too. Two new processes can reduce energy consumption and emissions, while there are benefits in self-generated energy

Where is no doubt that the paintshop offers the best ROI in terms of time and money spent when attempting to reduce carbon dioxide and VOC (volatile organic compound) emissions, or cut the amount of energy used across automotive production.

The reasons for this are explained by Professor Gordon Smith, Head of the Materials Group at WMG, the research institution based at the University of Warwick, previously known as the Warwick Manufacturing Group. He cites figures first published as far back as 1997 by General Motors, but which he says are still entirely relevant to any current discussion. Quite simply, more than 43% of the toxic emissions generated during the manufacturing process for an automobile can be attributed to paint operations.

That figure can be broken down into specific outputs for both VOCs and associated hydrocarbons. The average VOC output in the production of a single vehicle is approximately 5kg, so assuming a standard production rate of 60 vehiclesper- hour over a three-shift operation, the amount of VOCs generated per day would be 7,200kg. Disposing of those emissions through combustion would, even at the lowest feasible conversion factor, generate 165,600kg of hydrocarbons.

The situation doesn’t necessarily improve if solventbased paints containing VOCs are replaced by water-based products. A paintshop will still remain a huge energy sink, primarily because water-based paints must spend longer periods in curing ovens after the paint application process. Precise figures are also available for this. According to the US Department of Energy, the total energy consumption per vehicle in a car assembly plant is 1,290kWh, of which two-thirds – 860kWh – is electricity, while the remaining third – 430kWh – is made up of fuel. But, Smith points out, the average electricity consumption for a paintshop is 260kWh per car, even without the additional fuel used to heat the curing ovens. So using an estimate put forward by the former DaimlerChrysler, which says that 50% of all fuel consumed is used in the paint process, the total figure for paint-related energy consumption is 475kWh per car.

These basic figures can be translated into a further macroscopic estimate of the energy profligacy of a conventional automotive paint operation. Based again on the notional throughput of 60 vehicles-per-hour, or 1,440 vehicles over a 24-hour period, then according to Smith, the electricity used by an automotive paintshop totals 374,400kWh per day, with a corresponding fuel energy consumption of 309,600kWh per day. When those figures are added together, using a standard emission factor of 0.43 for the ratio of kgCO2/kWh for electricity, the baseline CO2 emissions come to 209 tonnes-per-day, for a grand total of 455 tonnes per day of CO2 emissions from a typical automotive paintshop.

A better way

Smith, though, does more than merely crunch numbers. The team at WMG has now developed what he claims is a practicable technology for the near ‘complete elimination’ of all the emissions produced by a conventional automotive paintshop - or at least those involved in painting moulded plastic parts. The result of research that has been on-going since the 1990s, the technology involves the ‘in-mould’ painting of such parts as they are formed.

But, as Smith explains, that initial work ran into a series of problems. First, it required a complex ‘dual injection’ methodology to be developed in which liquid paint was first sprayed into the mould to form a ‘skin’, followed by the plastic used to form the part. Second, it created visible and aesthetically-unacceptable flow lines on the surface of the finished part, especially when metallic paints were used.

Now, though, following new investigations supported with substantial backing from the Carbon Trust, the UK’s official agency for promoting CO2 abatement technologies, Smith is confident that a genuine zero-emissions paint processes for plastic parts will soon be a reality. As he explains, the original idea has been developed so that effective in-mould painting is now feasible using existing moulds, so there is no requirement for any expensive retooling. Instead, only some relatively minor ancillary equipment of moderate cost is required.

The key innovation is to use paint in powdered form that Smith says is ‘exploded’ into the mould using compressed gas moments before the molten plastic is injected in an entirely conventional manner. This simple change has a number of crucial implications, not least of which is that as the complete process takes place inside the mould, external contaminants cannot affect product quality. “The mould acts as its own cleanroom,” he explains.

By the same token, there are no effluents. Additionally, because the paint is introduced in powdered form, Smith points out another key benefit: “There are no solvents whatsoever.” The technique further obviates the problem of visible flow lines, while being suitable for any shape of part. “There are no real problems with [part] geometry,” he confirms.

That said, some refinements are still required. For instance, a technique for heating and cooling the mould has still not been finalised. Smith, though, can confirm that WMG is now working on setting up practical demonstrators, while the procedure is already attracting attention from manufacturers in various sectors, of which one is a multi-national producer of consumer electronics. Another is the UK arm of what he will only describe as a ‘major automotive company’, which has asked for some trial parts to be delivered for further assessment.

The bottom line, though, is that a process producing plastic moulded parts looks set to deliver substantial reductions in solvent wastage and CO2 emissions is now almost ready for industrial use. Smith says that there is no reason why the technique could not be in use ‘by the end of this year’.

Rubber process

Meanwhile, a major automotive supplier has announced that it has started delivering a product manufactured from a new and environmentally-efficient material. The company is US-based Federal-Mogul, which employs approximately 43,000 people around the world manufacturing various powertrain, chassis and safety technologies.

The innovation seems a relatively simple improvement in materials technology used in the company’s Unipiston range of hydraulic clutch pistons. Specifically, the company has developed what it describes as a ‘unique new elastomeric compound’, referred to as K16, that negates the need for energy-intensive curing in separate ovens after the in-mould forming process has taken place.

The nature of the development is confirmed by Larry Brouwer, Director of Technology and Innovation for Powertrain Sealing Systems with Federal-Mogul. Based in Southfield, Michigan, Brouwer says the location where the process has entered production at the company’s Frankfort, Indiana facility.

The basic process, which remains unchanged, combines metal and rubber in a press. The savings are derived entirely from the fact that the curing process previously required to vulcanise the unit’s elastomeric elements have been made redundant.

Brouwer indicates that the product as it exists has actually exceeded the original research goal, where the initial project, carried out at the company’s R&D facility in Ann Arbor, Michigan, only planned to find a way to reduce the required curing time. But as the project advanced, the goals were changed to focus on developing an entirely novel form of materials chemistry to radically cut energy usage.

That said, there were a lot of potential savings to be made in both time and energy over the original process, which involved baking the moulded parts at 175oC for up to twelve hours in natural gas-fired ovens. Brouwer says that the company has calculated that by eliminating the process, the company could reduce gas consumption at just the Frankfort plant by approximately 40 billion BTUs a year - which in turn would reduce CO2 emissions over the same period by around 2,000 tonnes.

While Brouwer is not at liberty to reveal precise details of how the advance has been achieved, he says that apart from the chemical composition of the elastomer, the other crucial technical element involved has been the development of an advanced process used to monitor and control the time the material spends in the mould, dependent on variations in temperature or the material’s own properties. Nevertheless the actual production process remains constant. “Cycle times are the same,” he says. “Nothing different happens inside the mould.”

Importantly, though, Brouwer confirms that the base elastomer used in the new formulation is the same as in the old. Consequentially, the material properties of finished parts made through the new process are, as he states rather ambiguously, “equal or superior” to those previously obtained. Nevertheless, he says that Federal-Mogul has needed to convince automotive customers of that, as on its own, environmental efficiency is not a selling point. “We did a lot of validation testing,” he states. “Customers had to be convinced.”

One area where the newly-developed K16 material has had an obvious and quite major impact is within the Frankfort plant. Brouwer says that almost all the Unipiston products made there now use the K16 formulation, meaning that most of the curing equipment has already been removed. Apart from the direct energy savings, this has also had a beneficial impact on part travel distances within the facility, inventory and work-in-progress. Only one customer, with what he describes as a ‘legacy product’, has yet to be converted. For the future, the company foresees the technology being applicable to a range of other products, such as oil pan gaskets or valve and engine covers. In fact, says Brouwer, it should be appropriate ‘to almost any type of sealing application’.


What can be taken away from these two cases is that process innovation can be a major driver of emissions reduction.

Yet, so too can product innovation. But what about tackling emissions further back up the supply chain by making primary energy generation itself as near to a zero-carbon process as possible? The wind turbines that now feature at various automotive plants serve to demonstrate that the sector is making appropriate gestures. But what is the reality in economic terms? Does self-generation of low-carbon energy actually make business sense?

These are questions that have been a addressed for over two years by a team of researchers in at the University of Wisconsin, Milwaukee. The team has worked closely with GM, which also provided financial backing, to analyse the realistic application potential for four different types of lowcarbon energy generation at six of the company’s locations across the globe. The four technologies involved are: wind power; solar photovoltaic (PV); fuel cells (natural gas); and fuel cells (hydrogen) at plants in North, Central and South America, Europe and the Middle and Far East - specifically: Detroit; Mexico City; Sao Paulo; Bochum; Cairo; and Shanghai.

The research was led by Professor Chris Yuan, from the university’s Department of Mechanical Engineering.

The initial findings were reported at a conference in the US last summer, but their formal publication is not due until June of this year. What they clearly show is that the economics of localised lowcarbon energy generation are extremely complex and require several factors to be evaluated. These are not limited to the efficiency of the technology involved and local environmental conditions, but also the carbon efficiency - or otherwise - of the relevant grid supply.

Yuan says that as far as he is aware, no similar research has been carried out in the past though as he readily concedes, much of the raw data involved is widely available. For instance, the solar insolation data, in the form of kWh/m2/ year was collected and published by NASA over a 22-year period, through mid-2005. The researchers’ own original input, he says, largely revolved around their development of ‘conversion’ techniques to turn environmental and performance efficiency data for the equipment involved into readily-comparable economic figures.

The relative efficiencies of similar technologies in different parts of the world can be widely variable. An interesting set of figures produced by the researchers shows the relative ‘capacity factors’ – defined as the ratio between the actual power output and the total rated power of the system concerned – for wind and solar PV. The PV figures remain in a relatively narrow band in which the lowest-rated location scores just over half the corresponding assessment for the highest. The actual scores (in ascending order) are: Bochum, 9.19%; Detroit, 11.84%; Shanghai, 13.15%; Sao Paulo, 15.48%; Mexico City, 17.62%; and Cairo 17.98%. For wind power, though, the gap between lowest and highest is far wider – the ratio is only fractionally short of 1:14. The actual scores are: Mexico City, 3.39%; Sao Paulo, 6.48%; Cairo, 15.97%; Shanghai, 28.09%; Detroit, 28.42%; and Bochum, 47.24%.

To some extent, the figures are what you might expect, since they reflect the consistency of technologies irrespective of location and the variability of environmental conditions. In short, Germany is windier than Mexico and less sunny than Egypt.

But if the aim of the most cost-effective investment is to reduce CO2 emissions using local power generation over the local grid, then the situation becomes more dynamic and provisional. Yuan explains the key variable is the carbon efficiency of the local grid supply. In Sao Paulo, much of the local power generation is based on biomass, a relatively low-carbon source. As such, there is really no worthwhile investment to be made there in pursuit of CO2 reduction. For every $1,000 invested in wind power technology, CO2 emissions would be reduced by just 0.467 tons per year. In comparison, the same investment in Shanghai would cut CO2 emissions by 20.564 tons a year; in Bochum, by 22.02 tons per year.

Investment aimed at cutting CO2 emissions has to involve far more than just good intentions. As Yuan notes, it is a complicated process of strategic decision making, the results of which may vary widely according to factors that are beyond the influence of the individual companies.