The farmers’ wish: a mechanical cow

Vafab Miljö is responsible for waste management in 12 municipalities, 10 of them in Västmanland, together with Enköping and Heby. There’s a biogas story here worth telling, that started with exclusive grain cultivation and a wish for a mechanical cow.

Biogasbuss i Västerås Biogas bus Monica Westman

Food waste has been collected in the region since 1994, initially to be used as compost. The food waste was collected in paper bags and composted in Sala, Fagersta and Västerås. But Vafab Miljö started eventually to think about digestion, and compared its procedures with those used in Linköping and Uppsala.

“We started to investigate whether biogas production was possible: the farmers wanted a digestion facility for forage crops, and we wanted to make sure that everyone was on board right from the start. We invited the public transport operators, the Federation of Swedish Farmers, local farmers, Mälarenergi, and several others”, remembers Per-Erik Persson, previously responsible for biogas operations in the region.

Grain cultivation

The farmers were not convinced: the fields had a high clay content, and they could support horses but only few cattle. But exclusive grain cultivation using commercial fertiliser cannot continue in the long term. Forage crops were needed in the cycle, and the farmers also wanted to reuse the nutrients present in the digestion residue.

Unga kossor på bete Photo credit Monica Westman“What they wanted was a mechanical cow”, says Per-Erik Persson.

At the beginning of 2000, Vafab was awarded a local investment grant for the construction: 17 farmers who grew forage crops and consumed fertiliser in the process joined the enterprise, and after a great deal of time and trouble, the fertiliser was approved for KRAV cultivation. It was fortunate that Västerås was allowed to take over SEK 25 million from the EU that had been intended for biogas expansion in Växjö, where Växjö had been forced to pull out.

The facility in Västerås came into operation in 2005. Further investment was required in 2008, and a new round of reconstruction and modernisation has been in progress since 2017.

“We lost money during the two first years, but we have made a profit every year since 2007”, says Per-Erik Persson.

Upgraded for vehicles

The gas has until now been derived from food waste after collection and sorting, from forage crops stored in plastic sheeting, from the waste-water treatment plant at Mälarenergi, and from the Gasum facility close by.

The material is divided into smaller pieces, sanitised at 70 °C and digested at approximately 40 °C with gas stirring. The gas produced is then upgraded to be suitable for use in vehicles and the digestion residue is dewatered to give phosphorus-rich solid fertiliser in the autumn and nitrogen and potassium-rich fertiliser in the spring.

Per-Erik Persson, biogas VästeråsPer-Erik Persson Photo credit Monica Westman“The facility is quite worn-out, but it just keeps chuffing along. We have a lot of gravel in the digestion chamber now, maybe as much as 20% of the volume. The reconstruction will give us a new digester, although we’re still keeping the old one, and we’ll be focussing on pretreatment and upgrading”, he says.

The facility produces 30 GWh of energy from gas, in addition to 23,300 tonnes of liquid fertiliser and 2,500 tonnes of solid biofertiliser each year. Filling stations for not only lorries, buses and work vehicles, etc., but also cars are available in Västerås, Fagersta, Sala and Köping. The farmers are happy with the results. Vafab Miljö has owned the production, distribution and delivery to the end customer, and all political parties in the region have agreed with the policy.

Biogas to 2025

Svealandstrafiken, which is owned by Örebro and the municipalities in Södermanland and Västmanland, now operates 180 buses, 98% of which are fuelled by gas, the others being fuelled by HVO and, in a few cases, electricity. It is planned to increase the number of electrically powered buses.

“One of the routes in Västerås, No. 5, is to be electrified in 2021, and seven buses will be purchased. The buses are for use in the urban areas. They use less energy and produce less noise, but cost more”, says Mattias Ceder at Svealandstrafiken.

“Buses fuelled by biogas can be used for all transport throughout the rural areas and suburbs, but the next procurement round is scheduled for 2025, and we will have to wait and see what happens. Until then, we’re looking at slightly increasing sales of the gas. We have to remember that biogas makes money for the public purse. This is a societal project in which nutrients are transferred from town to country”, he says.

“Biogas is the epitome of the circular economy”, concludes also Anders Porswald, regional executive for environmental matters in Västmanland.

Translation George Farrants

Linköping, Uppsala and Västerås
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