Pictures of the Future - Spring 2009
Life Cycle Planning | Rail Systems
Today's locomotives should consume as little energy as possible—not just when they are in operation, but also during production and eventual recycling. Life cycle assessments can help with selection of the most environmentally compatible designs.
Press picture
At a Siemens locomotive factory in Allach, Germany, efforts to maximize product environmental compatibility and flexibility include, among other things, the use of LED signal lights (below right)
Siemens locomotives are designed to be efficient—for instance by returning braking energy to the grid that is generated when traveling downhill
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The assembly hall is filled with locomotives, some of them missing their roofs, others without control cabins. And some are even mounted on temporary platforms that make them appear to be floating on air. Martin Leitel, who is responsible for making life cycle assessments of locomotives for Siemens Mobility in Allach, Germany, points to a yellow locomotive without a roof. "That one's going to Australia," he says, a country where rail service operators recently started making energy conservation a higher priority. In fact, the model will be the first electric locomotive on the island continent to be equipped with an energy recovery system. The system collects braking energy generated on downhill stretches by trains full of coal that are traveling from the interior of the country to the coast. It then feeds the energy into the grid for use by empty trains going uphill.
Another locomotive, Leitel explains, is for a European leasing company. It's equipped with a transformer that achieves optimal efficiency because it was built using more copper than is usual, which also makes it heavier than similar units. In order to compensate for the transformer's additional weight, other parts of the locomotive must be lighter, which is why its roof is made of aluminum. Naturally, all of this results in higher energy consumption during manufacturing. But, as Leitel points out, after only a few years of operation, the transformer's high efficiency and the aluminum's light weight counterbalance these energy costs.
Such conflicts are a part of Leitel's routine. In addition to conducting life cycle assessments (LCAs), his job at the Allach locomotive factory near Munich is to ensure coordination with customers when drawing up custom-tailored technical specifications for their locomotives. Combining these two goals has proved to be a good idea. "Customers simply want a good locomotive that meets the highest environmental standards," he says. What's more, life cycle analyses are often a prerequisite for taking part in tendering processes.
Quick LCAs.
Munich has been a locomotive production site since 1841—at one time under the name Krauss-Maffei, whose logo still adorns the front of the factory hall that Siemens took over in 1999. But much has changed over the years. While steam locomotives churned out enormous amounts of soot and carbon dioxide, their modern counterparts are subject to strict environmental regulations. And it's not just the emissions caused by operation of these powerful locomotives that need to be low; environmental impact throughout their entire life cycles must also be kept to a minimum. This begins with the manufacturing process and continues all the way through the product's life to disposal, which will soon become the legal responsibility of the manufacturer. As a result, developers must now plan to recycle as many components as possible.
To ensure that the associated analyses—also known as material balances—remain accurate, Leitel relies on an extensive database containing thousands of parts numbers and information on the materials used in each component. This database reveals, for example, that the left door of a locomotive control cabin weighs 87.1 kilograms, including 68.1 kg of aluminum, 6.6 kg of glass, and 4.2 kg of elastomers, with the remaining weight accounted for by other materials, including steel and insulation elements.
Just a few mouse clicks is all it takes to evaluate specific assemblies or material classes and determine their proportion of total weight. Another database lists the primary energy consumption and carbon dioxide emissions associated with each material, as well as regional differences. For example, an aluminum panel made in Iceland, a country that uses a lot of renewable energy, has a much lower CO2 value than one from China, where most electricity is generated in coal-fired power plants.
The material analysis does not extend down to the last bolt; this would require too much effort and expense. "We make a general estimate of the energy consumption and emissions of small components," Leitel explains. The analysis ultimately produces charts that show where energy consumption is highest. With freight trains it's clearly locomotive operation itself. Over a service life of roughly 30 years, a locomotive in Europe emits between 200,000 and 400,000 t of CO2, depending on the type of use. Locomotive production results in only about 250 t of CO2 emissions, however. And the recycling phase generates savings of 100 t of CO2 because over 95 % of the materials in a modern locomotive are recyclable. These materials—for the most part metals and coolants—are reused, which obviates the CO2 emissions that would have been produced if the materials had been manufactured from scratch.
Materials Review.
Leitel believes that the material analysis process can be improved. "We're reviewing the entire range of materials now in use," he says. The idea is to use batteries that don't contain heavy metals, as well as coolants made of biodegradable materials—and to generally ensure that new designs have more recyclable parts by avoiding use of composites as much as possible. "The ideal would be to loosen a few bolts and have the whole locomotive break apart into sets of unmixed materials," Leitel explains.
Not every trend is as good as it sounds, however. Although lightweight construction with plastics and composites reduces operating energy consumption, it also poses recycling problems, which means that it is not necessarily good for the environment. A locomotive also shouldn't be too light because it has to pull a train 20 to 30 times its own weight. When asked if all the environmental effort that is now being implemented will ultimately pay off in the form of orders, Leitel says he's certain it will, but cautions that "the locomotive market is price-sensitive, so the sales price is still often decisive."
Nevertheless, customers are well aware of the fact that the purchase price of a locomotive is only around 15 % of the cost of powering it throughout its service life. "So a 10 % higher list price for a locomotive still pays off for the customer if energy efficiency is two percentage points better than the competition's," Leitel points out.
Recyclable Subway.
This argument is familiar to Dr. Walter Struckl, who works at Siemens Mobility in Vienna, where subway trains, railway cars, and trams are built. The market for these products is also extremely price sensitive, and energy-saving innovations here have to pay for themselves within two to three years. Struckl opens a copy of his doctoral dissertation from Vienna Technical University. In this work, Struckl calculated down to the last detail the energy balance of the Oslo subway system—probably the most efficient subway in the world in terms of resource conservation. When Struckl joined Siemens in 2003, it still wasn't possible to market the environmental aspects of a product, but today LCAs are a normal part of the tendering process. Life cycle costs have to do with costs, but life cycle assessments address environmental concerns. People tend to confuse the two, says Struckl—but they're not contradictory, given that greater energy efficiency usually has a rapid and positive effect on life cycle costs.
With regard to the Oslo subway system, a total of 84 % of its materials can be recycled; the rest are burned and the resulting energy is exploited. There isn't much left to improve here because the rail cars are held together with hook-and-loop fasteners rather than glue, for example, which makes it easy to disassemble them.
The LCA, however, can still be improved. Experts estimate that an additional 30 % in energy savings could be achieved in actual operation and that the associated costs would be recouped in one year, says Struckl—even though the system already consumes around one-third less energy than its predecessor, mostly thanks to more efficient heating and more effective insulation.
Mobility in Context.
Struckl warns against generalizations, explaining there is no such thing as a "good" or "bad" LCA. Absolute numbers, such as those for CO2 emissions, don't reveal much in and of themselves. Instead, each application scenario must be carefully studied in context in order to develop optimal measures. Subway trains such as those in Oslo, for example, produce only 827 metric tons of CO2 during a 30-year service life—a low figure due to the fact that 99 % of Norway's electricity is generated with hydro power. On the other hand, the same trains would emit 47,900 metric tons of CO2 equivalent if operated in the Czech Republic because most of that country's electricity comes from coal-fired power plants. But unlike Oslo's trains, Prague's run mostly underground and its winters are warmer, meaning that its trains can get by with less heating and that an investment in improved insulation wouldn't really pay off anyway. What would pay dividends, says Stuckl, would be a more efficient drive unit like the Syntegra bogie with its permanently excited gearless electric motors, which Siemens is testing as a prototype (see Pictures of the Future, Fall 2007, Road to a Lighter Future).
Struckl's goal is to turn the focus away from the LCA of individual assemblies and toward the overall mobility system. Siemens offers devices that store braking energy either on trains themselves or as stationary units on tracks. The company also supplies efficient technologies for producing electricity at power plants and transporting it to tracks, as well as traffic management systems that intelligently network rail and road transport. Siemens' Complete Mobility concept attracted lots of interest at the Innotrans fair in September 2008 in Berlin. These days, companies in Norway receive a cash bonus for every kilowatt-hour of energy saved; and other countries plan to introduce emission trading systems for the transportation sector. "When transport companies also begin to bear the cost of carbon dioxide emissions, many of them will quickly become interested in our innovations," predicts Struckl.
Bernd Müller