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Swedish Transport Administration to pilot verge grass collection for biogas

Each year, the Swedish Transport Administration cuts around 200 000 kilometres of roadside verges across the country to provide improved visibility and better safety for motorists. A pilot project in the province of Skåne, southern Sweden will test a new method that will collect the mown grass and use it as a feedstock for biogas production.

Commissioned in 2013, the Jordberga biogas and biomethane-to-grid plant was built by Swedish Biogas International in collaboration E.ON, Skånska Biobränslebolaget, and Nordic Sugar and acquired in full by Gasum in 2017. The plant uses around 90 000 tonnes per annum of green waste and residual organic matter from agriculture and the food industry to produce 110 GWh of biomethane to the gas grid and 80 000 tonnes of biofertilizer (photo courtesy Gasum).

Many different plant species grow on roadside verges, the strip of land between the roadside and outer boundaries such as a ditch, fence, hedgerow, or wall. Some of the rarer the meadow plant species thrive even better if the cuttings from the verge are removed.

The Swedish Transport Administration (Trafikverket)has therefore investigated how roadside verge cuttings can be used to produce biogas. Now the ideas are being tested with a pilot project that will take place in Trelleborg, Skurup, and Svedala.

The project will run on smaller, state roads in the three municipalities for three years starting in the summer of 2020. With a specially developed mower, the vegetation will be cut, collected, and transported to a biogas plant in Jordberga.

At the biogas plant, the biomass will be converted to biogas via anaerobic digestion (AD), upgraded into biomethane – aka renewable natural gas (RNG),  injected and distributed via the gas grid. An additional benefit is that a residual product is a high-quality digestate, which can be supplied to agriculture in the region.

Contributes to climate targets

It is hoped that the project will contribute to a reduced climate impact by increasing biogas production, biogas that can replace fossil fuels in, for example, vehicles.

On the roadside, there is a large amount of biomass that is not currently used, but which could be used for large-scale energy recovery across the country. With this pilot project, we want to find the forms for such extensive energy extraction, and thus be able to contribute to the Swedish Transport Administration’s and Sweden’s climate goals, said Sven Hunhammar, the Swedish Transport Administration’s environmental director.

The Swedish Transport Administration has targets for a climate-neutral infrastructure by 2045. As a sub-target, the climate impact from the traffic infrastructure will be reduced by 15 percent by 2020, 30 percent by 2025, and 50 percent by 2030, compared with 2015.

The biogas to be produced during the three years of the pilot project is estimated to give an emission reduction corresponding to more than 700 tonnes of carbon dioxide for the three years the project is ongoing. This corresponds to roughly what 400 passenger cars emit in a year. We expect this benefit despite the pilot project being carried out in a very limited area. This means that if this way of working can start to be used throughout the country, we see great potential, said Sven Hunhammar.

Stimulates biodiversity and prevents the spread of invasive species

The regular mowing that has been carried out continuously over the decades has resulted in the development of many roadside verges into important biotopes and refuges for rare and endangered meadow plants and insects.

It is hoped that recurring mowing with seed collection will also limit the spread of invasive species, such as lupins, which are often spread along roads and compete with the native fauna.

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