What will the mobile world of tomorrow look like? Which energy sources will replace fossil fuels and what effects will they have? The developers at Linde Material Handling GmbH (Linde MH) are always asking themselves these questions. Based on a cooperative effort with the former sister company Linde Gas Division, the manufacturer of forklift trucks and warehouse equipment in Aschaffenburg is now able to present the results of a project to develop an alternative drive concept — two fuel-cell powered fork-lift trucks for everyday use. The innovative trucks were tested and introduced in mid-May at the 'Linde Hydrogen Centre', which is part of the Gas Division of Linde AG in Unterschleissheim.

"The concept for a fuel cell truck appeared both simple and ingenious", explained Hannes Schöbel, Product Manager for Innovative Drives at Linde MH with a wink. "We simply replace the battery on an electric forklift truck with a fuel cell." Of course, it was not quite so simple for the engineers. Development of the trail-blazing trucks with model designation Linde E30 Fuel Cell (FC) took almost two years. Together with Hydrogenics — a Canadian company with which Linde has worked together for many years, and a leading manufacturer of fuel cells — Linde's developers thrust all of their expertise into the new drive concept. As part of this development work, the team in Aschaffenburg was able to draw upon many years of pioneering work and competence building. As early as 2000, and again in 2008, a prototype/design concept truck based on fuel cells was presented at the CeMAT exhibition for intralogistics in Hanover.

The future belongs to alternative drives
Product Manager Schöbel is convinced that, in addition to conventional drives, there will be alternative types of drives for trucks. This is because of the dwindling oil resources and the resultant, continually increasing prices for this "black gold". At the same time, efforts to reduce emissions are being pursued in all areas. Even the automobile industry has set the course for hybrid drives and electric-powered mobil-ity. The internal combustion engine will not, of course, completely disappear in the next twenty years, since it offers enormous power reserves and still represents the most economical solution in many cases.

However, electric drives are impressive due to their lack of emissions and low noise level. "Electric fork-lift trucks can be employed without any concerns in closed areas", states Schöbel. The drawback they have, however, is the large amount of time needed to recharge or replace the batteries compared to refuelling with diesel fuel, LPG or natural gas. "In contrast, the fuel tank of the ten-kilowatt fuel cell package from Hydrogenics can be refilled in a few minutes, just like a truck powered by an internal combustion engine." Furthermore, additional space may need to be provided in the warehouse for replacement batteries and charging stations. Finally, there is also the problem of battery acid in hygienically-sensitive sectors such as the food and the pharmaceutical industries.

In the USA, fuel-cell technology is already being used in a number of successful companies. The giant retailer Wal-Mart, for instance, has been using just under 70 fuel-cell-powered warehouse devices at a site in Ohio for some years now. "This shows that hydrogen-powered trucks are already a viable concept today", explains Markus Bachmeier, manager of the 'Hydrogen Solutions' area at Linde AG. In his opinion, forklift trucks could become the leading market for fuel cells, "since economy is the primary concern here". The refuelling systems at Wal-Mart were supplied by Linde Gas. "There have been more than 50,000 refuelling since the commissioning of our petrol pump in Ohio."

The reasons for the introduction of this technology among 'early adopters' vary considerably and range from hygiene requirements to strict environmental regulations and boosting the company's image. Wal-Mart uses the fuel-cell powered trucks for the following reason: fast refuelling with hydrogen and the constant output translate into a considerable time savings and improved performance compared to the large amount of time needed to replace and charge conventional lead-acid batteries in the course of their service life. The shift work in the Wal-Mart warehouses thus becomes more productive.

At Linde Gas, the decision to use the innovative trucks by Linde MH was obvious: the Linde Hydrogen Centre has been operating one of the most modern hydrogen refuelling stations in Germany since 2006. "For facilities where hydrogen is generated as a by-product or those that already have hydrogen refuelling systems, our new forklift truck represents a possible alternative", explained Hannes Schöbel with regard to possible symbioses. The two trucks involved in the German pilot project in Unterschleissheim replace two diesel trucks. One fuel-cell truck operates in the gas bottle filling area; the other is used to transport gas bottles between the production building at the site and the truck loading docks. The production building and refuelling station are separated by a public street. This presented a special challenge for those involved in the project, since the trucks needed to be road legal in order to cross the street. However, working in close cooperation with the technical staff at TÜV South, the engineers at Linde MH ultimately satisfied all necessary requirements and approval was granted. The fuel-cell model thus represents an option that customers can order today and makes Linde Material Handling the first manufacturer in Europe with a fuel-cell truck in its product range.

"The new truck with the alternative drive is actually based on one of our best sellers", says Hannes Schöbel. What he is referring to is the Linde E30 3-ton electric counterbalanced model. The elevated cab version provides an optimal view of the load as well as additional space to accommodate the fuel cell and a tank to supply the cell with hydrogen. Eliminating the battery, however, presents new requirements regarding weight distribution. Henning Meth, one of the developers of the Linde E30 FC knows all about this. "The 80-volt lead-acid battery used in the basic model weighs approximately 1.8 tons, while the fuel cell that replaces it only weighs about 500 kilograms", he explains. The truck, however, needs a sufficiently large counterweight to ensure the load capacity and stability of the fuel-cell truck. "This meant that we had to incorporate a ballast weight into our plans". The "supercaps" are another special feature of the fuel-cell truck. These are large capacitors that function as buffers and cover performance peaks, such as when climbing inclines or lifting.

Fuel in two different forms
The tank of this new industrial truck has a capacity of 1.6 kg of gaseous hydrogen. It is filled in less than three minutes at a pressure of 350 bar at special refuelling stations equipped with a CGH2 filling pump such as that at the Linde Hydrogen Centre. For a better understanding: CGH2 is an abbreviation that stands for 'Compressed Gaseous Hydrogen'.

At the Linde Hydrogen Centre, however, hydrogen is stored in liquid form in a vacuum-insulated tank at a temperature of -253°C. In this physical condition, the hydrogen has a considerably higher density. Storage in liquid form thus means that larger amounts can be accommodated in less space. For instance, the storage tank at the Linde Hydrogen Centre can hold up to 17,600 litres or approximately 1100 kilograms. A special pump transfers the liquid hydrogen from the tank to the LH2 dispenser. To supply the CGH2 dispenser, the liquid hydrogen is processed in a special way. A compact electric evaporator converts the physical condition of hydrogen from a liquid into a gas. A two-stage compressor station then raises the pressure of the hydrogen to the 350 bar needed for filling the tank. "When it comes to the subject of refuelling station infrastructure, the pioneering role of the forklift truck among the initial commercial applications of fuel cells once again becomes clear", explains Linde Gas Manager Bachmeier. "While in the automotive sector you need a density of about 50 filling stations to supply one automobile, one filling station can serve 50 trucks for material flow within a company."

Clean and safe
An important aspect when using hydrogen as a mean of fuel is naturally always safety. Lay people remember from their chemistry lessons or pictures of the “Hindenburg” which went up into flames in 1937 that there is a certain danger with hydrogen. Refilling a tank at a hydrogen refuelling station, however, is comparable to refilling a tank with natural gas and thus safer than a conventional petrol pump for gasoline or diesel. When filling the truck's tank, the tank coupling of the hydrogen dispenser attaches securely, ensuring that no gas can escape in an uncontrolled manner while fuelling. In fact, reliability and the safety of the vehicle were of primary concern when designing the fuel-cell truck. "For instance, the gas system on the Linde E30 FC is protected by means of relief hoses to prevent impermissibly high pressure and temperature", explained design engineer Henning Meth. "In the event of a malfunction, a relief line directs the hydrogen out over the overhead guard." Of course, in addition to the systems them-selves, the vehicle operator is one of the major factors when it comes to ensuring maximum safety. "This requires a certain degree of technological competence for dealing with hydrogen and fuel cell technology, but a customer's employees can be trained quickly in this regard", explained Markus Bachmeier.

The new Linde E30 FC is by all accounts innovative, safe and environmental. But what are the associated costs? According to Product Manager Hannes Schöbel, the purchase price is about three times that of the basic model with lead-acid batteries. "In return, customers have a piece of the future that is suitable now for everyday use, with the combined benefits of combustion and electric drives", states the Product Manager. During the two months since their commissioning, the two new trucks at Linde Gas have already clocked up 250 operating hours without any difficulties. Projects of this kind are important for both Linde MH and Linde Gas as a way to secure and expand their own positions as innovative leaders. "Ultimately, it takes a pioneering spirit to transform the ideas of tomorrow into reality", states Schöbel.

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Your contact:
Detlef Sieverdingbeck
Phone: +49 (0)6 021-99 14 07
E-mail: detlef.sieverdingbeck@linde-mh.de

Heike Oder
Phone: +49 (0)60 21- 99 12 77
E-mail: heike.oder@linde-mh.de