In collaboration with Linköping-based energy recovery specialists Tekniska verken, Scania Engines is currently testing one of its engines using raw gas, biogas that is untreated—i.e., not cleaned or upgraded to remove wastewater, CO2 and other particles, as happens with the production of compressed natural gas for vehicle fuels. Instead, the raw gas is taken directly from the digestion chambers as fuel for the Scania engine, to see how it performs over 600 hours of tests.
The engine is a Scania 16-liter V8, made for low-pressure compressed natural gas for power generation. The unit is switchable between 1,500/1,800 rpm to produce between 333 kW and 426 kW prime power. COP (continuous operating power) is 330 kW (50 Hz), 350 kW (60 Hz). Gas feed pressure is 50 mbar.
Scania’s hope is that if the engine can work with this raw gas, it will be an even quicker and cheaper process of producing biogas for power generation, and another valuable source of alternative energy from recycled material.
We have been working with Tekniska verken for the past two years, initially with compressed natural gas, and we started testing raw gas in early 2017. In September 2017 we carried out the latest round of testing and have been reviewing the results during the following months.—Holger Mattsson, Project Coordinator at Scania Engines
Tekniska verken produces compressed natural gas (CNG) to be used as vehicle fuel. Indeed, the city of Linköping, which owns the company, runs its bus system exclusively on CNG. But while Tekniska verken’s focus is not necessarily on raw gas, Erik Nordell, the Development Engineer at Tekniska verken who has been coordinating the work with Mattsson and his Scania team, says Tekniska will be taking a close interest in the results of the tests.
Scania is also set to work with Telge Återvinning in Tveta, Södertälje, a waste-recycling entity owned by Södertälje council. At Scania’s instigation, the pair run tests to see how Scania’s engines can run on simple gas—in other words, gas that is extracted directly from landfill sites.
This will mean taking the gas directly from source—without refining or upgrading—by drilling holes directly into Telge’s landfilled waste. Even though Tveta stopped taking landfill in the 1990s, the biogas by-product from the organic waste digestion process continues to be available for up to 30 years after burial.
There are landfill sites all over the world, and if we can effectively use the lower-quality gas that comes directly from these sources, there is huge potential for the market and for consumers.—Holger Mattsson