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Biomass Magazine: Reinventing the Rail Car


A three-party collaboration between Drax, Lloyd's Register Rail U.K. and WH Davis has yielded the world’s first pellet rail wagon, which maximizes the efficiency of each train load that rolls out of Britain's ports.

By Tim Portz

Converting the United Kingdom’s largest power generation station to the world’s largest biomass power facility is driving transformation all along the supply chain that feeds it. Each of the three boilers that U.K.-based Drax is converting from coal inputs to biomass will consume nearly 2.5 million tons each year. These volumes will originate predominantly in North America, with the final leg of the journey being a short rail ride from the U.K.’s network of ports to the Drax power station. 

In the earliest phases of this stepped transformation, Drax modified a number of its fleet service cars to deliver the facility’s first shipments of biomass.  Coal is much denser than biomass, however, so filling rail cars designed to carry coal with biomass was too inefficient to tolerate as a long-term solution. Recognizing this, Drax turned to Lloyd’s Register Rail U.K. to design the world’s first purpose-built biomass rail wagon. 

“This was to be an industry-leading wagon and even NASA wouldn’t be able to design a better one,” says Graham Backhouse, head of supply chain and logistics at Drax.

The challenge was to design a rail car capable of hauling significantly greater volumes of material in each car, thereby maximizing the efficiency of each train load of biomass that rolls out of Britain’s ports. The design team at Lloyd’s had to find room for not only additional volumes of material, but also for the wagon’s brake equipment, control equipment and pipework. The design that emerged was a nearly 19-meter-long (62.3 foot)rail car with a 116-cubic-meter (256 square foot) capacity. Keeping the biomass dry are two pneumatically driven doors for each car, and a patented flow control discharge system guarantees that pellets end up only where operators want them.

While rail car design grew out of collaborations between Drax and Lloyd’s Register, fabrication of the wagons was entrusted to WH Davis, the last independent British manufacturer of rail wagons. “The Drax wagon is effectively a super-sized hopper, in that the cubic capacity is larger than anything that is currently operating in the U.K. network,” says Ian Whelpton, sales and marketing director, WH Davis.

The fabricators at WH Davis begin by building a collection of subassemblies that are fused to the body of the wagon in the company’s main production hall. The wagon body and subassemblies are all installed with the aid of a large rotator that spins the rail car on an axis, allowing workers to move methodically around the car performing the welds that connect components to the finished freight wagon.

The first rail car was unveiled at the National Railway Museum in York, in late June. “The finished product is an industry-leading design and fulfills all the criteria we set,” says Peter Emery, production director at Drax. We may be launching it in a museum but this wagon is no museum piece and will not be surpassed for many years to come.”

Drax’s investment in 200 purpose-built wagons is just one component of investment the company and its partners are making all along the pellet supply chain. This investment reaches back through U.K.-based ports into U.S. port infrastructure, on through to production facilities, and ultimately, into the forests themselves. While Drax is not alone amongst power producers in the U.K. pursuing a transformation to increase biomass utilization, it is the first. With that distinction comes the burden of transforming not only its generation assets, but also the infrastructure that will ultimately deliver the low-carbon biomass fuels required, one rail wagon at a time.