Energy management has become a key criteria for tier suppliers’ equipment and systems

The rush to implement renewable energy sources – in the form of solar panels, wind turbines, or co-generation plants – has gone some way to stemming the rising energy costs of auto production, but not far enough. OEMs have been forced to look for additional solutions and their scrutiny has shifted inside the factory; first to the relatively ‘easy’ areas (lighting and HVAC) and now to the manufacturing process itself.

“Automotive manufacturers are doing everything possible to reduce the CO2 emissions of their vehicles,” explains Dirk Gorges, senior vice-president, sales and marketing PFS, at Dürr. “This thinking does not stop with the vehicle’s driving characteristics, but also relates to the production of the vehicle. OEMs have a vested interest in sustainable production and if new technologies save energy, materials and cost, then there is not much point spending time thinking about it.”

Managing assets

OEMs’ focus on energy management coincided with a rethink about the role of energy as a whole. It is no longer viewed as simply a cost but a valuable asset, a resource that if invested wisely, can add value to the product and increase profitability. Marcia Walker, senior director, sustainability marketing at SAP says: “Assets may be financial, they may be human – sometimes these are the biggest assets of the company – even machine assets. But really energy is just another asset, it just happens to be invisible.

“Our message is that energy is the most important invisible asset that companies have and they are now realising that they have to manage it with the same diligence that they manage their other assets. In manufacturing, energy can be consumed, much as cash is consumed in a financial transaction, but in other cases it can actually be invested into something that is going to increase your profits. “Energy should be managed just as parts, workers and other assets are managed through the supply chain. It is an ingredient in the manufacturing process.”

The shift from focusing on input costs to managing energy efficiently is one endorsed by Todd Montpas, automotive and tyre market development manager at Rockwell Automation. “Typically automakers have looked at energy from the sub-station level and now they are trying to move it to the manufacturing level to see if they can build the processes better,” he explains. “They are building a greater variety of cars so the process has to change to support this – and that lends itself to some forced opportunities to look at energy efficiencies and load shedding.”

Consumption visibility

Providing visibility of energy consumption – from the factory floor to head office – is vital for its effective control. “On the factory floor we’re batting energy objects into our controller level, so as you use things such as variable speed drives and some of the smarter devices that are being seen on the factory floor, that data is readily available,” adds Montpas. “We leverage our architecture’s logic-based infrastructure as well as our view platforms to be able to capture that and send it across the network, and then also display it locally at the operator level. We then use our operations management execution systems level software functionality to display that right down to a line cell, through a plant and then between plants as an enterprise level view.”

Painting a new efficient picture

Given their energy-intensive processes, it is no surprise that the main focus for energy efficiency goes into the paintshop. “We have guidelines that we follow whenever we develop or build products,” says Dr Michael Schlipf, specialist for chemical process technology at Eisenmann. “We manufacture installations that require the smallest amount of what we call ‘fresh’ energy; that is, energy that we have to feed into the system from outside.

“Whenever it is possible to use energy that we already have in the process, we recycle it. We also try to build installations that are small, so you don’t have to treat too much; we only use the minimum amount of air required for the paintshop. We try to close all of our processes so that we can minimise emissions – we like to think of anything that leaves the process as a cost.”

“The fact that the most sustainable automotive paintshops are currently found in China is simply due to the fact that the majority of new paintshops have been installed there, and these were equipped with our latest technology,” remarks Dürr’s Gorges.

One such plant is the resource-efficient BMW Brilliance Automotive plant in Shenyang, China, where the goal is to create nothing short of the world’s most environmentally friendly plant.

RoDip M rotational dip coating is used in the PT/ED area. Here, the rotational movement of the car bodies allows inclined sections at the entrance and exit of the dip tank to be eliminated. This leads not only to significant savings of space, but also to a reduced consumption of energy and chemicals due to smaller bath volumes. Other technical features include the fully automatic Integrated Paint Process (IPP), which eliminates the need for primer and thus a trip through the oven. The spray booths are equipped with EcoDryScrubber technology, the dry separation method from Dürr, which requires no water or chemicals.

The net result is a 60% energy saving because of reduced requirement for air recirculation. Paint will be applied with 32 type EcoRP E033 and EcoRP L133 painting robots from Dürr, equipped with the latest generation of atomiser, the EcoBell3, characterised by its significantly higher atomiser performance. Due to the EcoBell3’s compact design, both exterior and interior painting can be done with the same rotating atomiser. “The EcoDryScrubber alone saves 60% of the energy in the spray booth,” reveals Gorges. “Our EcoRP painting robots also contribute to energy savings with higher throughput because of a greater surface covering capacity. And with our EcoEMOS process control system we further optimise energy consumption through intelligent plant control.“

Waste heat recovery

At Shenyang, even the waste heat from the dryers is recovered through a waste heat boiler and the exhaust air stream from the clear coat booth is purified over and above the regulatory requirements before leaving the facility. Through the use of membrane technology in the pretreatment, electro dipping and waste water system, both water consumption and the amount of waste water are also reduced.

“At present we are already achieving a power consumption of 430kwh per car body,” says Gorges. “By way of comparison, only 10 years ago this figure was well over 1,000kwh. But even this figure is only a snapshot. We’ll be able to prospectively save up to 30% energy for painting with the new EcoRPC robot control.”