SIEMENS

Malgorzata Kroban spent months traveling to manufacturing workshops and production halls every day. The young engineer visited Osram glass manufacturing centers, where glass cylinders and tubes are made from a large number of materials melted together in giant hot furnaces.

Kroban witnessed lamp bodies being coated with phosphor, filled with gases, fitted with electronic circuits and stuck to plastic parts. She spoke with factory managers, researchers, and developers, and sifted through numerous databases. Her objective — which was also the topic of her doctoral dissertation at the Brandenburg University of Technology in Cottbus, Germany — was to put together a comprehensive environmental balance sheet for fluorescent lamps and various other Osram lighting systems.

"This dissertation marked the first time that the entire lamp life cycle had been closely examined — everything from quarry operations and extraction of the materials for the glass to recycling and disposal facilities," says Christian Merz, a sustainability expert at Osram. It was thus at once a premiere and a complex detective assignment. Every detail had to be identified and recorded. Where do raw materials come from, and how are they extracted, transported, prepared, and processed? What exactly occurs during the manufacturing process, and which machines and tools are needed? How much material and energy is used, and which energy sources are involved? How much electricity do the lamps consume when operating; how long do they last? And finally, which substances are recyclable, and can therefore be re-used when the lamp reaches the end of its service life?

The results of Kroban’s extensive investigation made one thing very clear: "The environmental balance sheet for lamps is largely determined by their energy consumption during operation," she says. As Kroban discovered, only one to 2 % of total lamp energy consumption is attributable to lamp production. "That’s why efficiency during operation is the most effective lever for making lamps more environmentally friendly," says Merz. "So, if we can raise lamp luminous efficiency even just one or 2 %, we’ll achieve more than if we covered up all our smokestacks and no longer released production-related carbon dioxide into the atmosphere."

The desired efficiency increases can be attained through extensive refinements, such as limiting tolerances during production in order to minimize a lamp’s environmental impact. Soon, for example, it should be possible to fill lamps with precisely the amount of gas needed to make them light up most efficiently. Implementation of many such measures can raise the luminous efficiency of today’s common lighting systems by around 20 %.

When Less is More. Osram’s developers can also use such life cycle analyses to identify those parts of the production process where resources can be conserved, and future waste thus prevented. For instance, Kroban’s studies show that in some cases, energy consumption can be reduced by using less material. The Osram T5 fluorescent tube, for example, which is about as thin as a finger, performed much better in terms of energy efficiency than the commonly used T8 tube, which is as thick as a broomstick. The "leaner" model actually consumes around 40 % less energy while delivering the same level of brightness.

Osram and the Energy Research Center in Munich began assembling data on the energy consumption of lamps 20 years ago. Since then, Osram has continually updated its figures. According to this data, by simply switching to modern lighting solutions, around 900 bill. kWh would be saved, or one-third of the electricity currently being used for lighting. Given today’s energy mix for electricity production, that would be equivalent to a 450-million-ton reduction in carbon dioxide emissions each year. "You’d have to plant 450,000 km² of forest — an area about the size of Sweden — to achieve the same effect," says Merz, who adds that it therefore makes sense to ban incandescent light bulbs. "That’s a good idea — and we’ve already got the lamps in stock to replace them with," he says.

Comparing Life Spans. For the sake of comparison, Osram scientists have examined the energy consumption and life spans of various types of lamps. Among the light sources compared were a 75-W incandescent bulb and a 15-W Osram Dulux EL Longlife energy-saving lamp, both of which have practically the same brightness. What the researchers found was a huge difference in energy consumption. Not only is this due to the fact that the energy-saving lamp can convert more electricity into light than heat; it’s also because the energy-saving lamp can operate for 15,000 hours, or 15 times longer than the incandescent bulb. The collective energy consumption of 15 light bulbs is therefore five times higher than that of a single energy-saving lamp that burns for exactly the same amount of time.

Conversely, an energy-saving lamp saves a total of one megawatt-hour of electricity during the same operating life span, which corresponds to half-a-ton less in carbon dioxide emissions than a conventional bulb. "That’s more than a tree can absorb during the same period," says Merz. The modest energy consumption of fluorescent lamps also saves money. Although they cost around €10 more than a conventional light bulb, fluorescent lamps pay for themselves after about 800 hours of operation — and save their owners €250 over their entire life span.

Moreover, because they are long lasting, energy-saving lamps — seen in a life-cycle context — consume less energy during production. That’s because even though the production of one lamp requires five times the energy used for a conventional bulb, a total of 15 bulbs would have to be produced to achieve a similar total luminous output.

Energy-saving lamps do pose one environmental problem, though: They contain mercury. "Without mercury, their luminous efficiency would be two-thirds lower," says Merz, explaining why Osram still needs to use the toxic heavy metal. Still, the lamps hold only one tenth the mercury that fluorescent lights had around 30 years ago. "That’s less mercury than a coal-fired power plant releases when it produces the electricity used by a conventional light bulb during its lifetime," Merz reports.

Nevertheless, over the long term, mercury will have to be eliminated from the lamps. In fact, there is already a fluorescent car headlight on the market known as "Xenarc Hg free" that employs a potassium-iodine compound that produces sufficient lighting power without any mercury.

Kroban’s dissertation serves as a valuable foundation for further environmental balance sheets being drawn up by Osram for new products. "Our goal is to market only those products that are more environmentally friendly than their predecessors," says Merz. With this in mind, the company is producing an environmental balance sheet for light-emitting diodes. These pinhead-sized lamps can already compete with fluorescent lamps in terms of efficiency, and use of new materials should significantly increase their luminous efficiency.

At the same time, a lamp developed on the basis of environmental criteria is worthless if no one buys it. "That’s why we always have to determine how appealing a lamp is to consumers," Merz explains. Such a study could necessitate altering lamp shapes to conform with consumer tastes, even if a different design would offer a technologically superior solution. It’s also important that the lamps have a dimmer function and can be easily integrated into existing lighting systems.

Of course, they should also emit pleasant, natural-looking light. After all, environmentally-sound lighting should create a relaxing effect. But there’s no time to relax for Osram’s lamp developer. They’re already busy working on the next generation of innovative lighting systems.