Swedish Forestry Waste to Energy Plant Keeps Costs Down with Organic Rankine Cycle

The Marjarp 2 biowaste to energy facility in Falkping, Sweden - the first power plant in Scandinavia to use hot oil Organic Rankine Cycle - has completed its first year of service, producing 2.4 MW of electricity and 10 MW of district heating.  

The Marjarp 2 biowaste to energy facility in Falköping, Sweden - the first power plant in Scandinavia to use hot oil Organic Rankine Cycle - has completed its first year of service. According to Saxlund International which supplied much of the technology at the plant, others could learn from the Swedish experience…

While the idea of small-scale biowaste energy solutions in the 2 to 5 MW energy range to provide Combined Heat and Power (CHP) is just starting to catch on in the UK, in mainland Europe, especially Scandinavia, the technology already plays a considerable role in delivering secure, affordable, green energy.

Marjarp 2 supplies district heating and electricity, producing 2.4 MW of electricity and 10 MW of district heating, from locally sourced forestry wastes such as bark and other residues as well as virgin timber.

The plant was commissioned by Falbygdens Energi from Saxlund International and is the first in Scandinavia to use hot oil Organic Rankine Cycle (ORC) technology for electricity production - as opposed to conventional high pressure steam systems.

Saxlund said that this means that engineering costs to deal with traditional pressurized systems can be reduced and overall it is a more cost effective option.

The project cost around SEK 85 million ($11.5 million) to develop.

Size matters

According to Matt Drew, managing director of Saxlund International, the relatively small scale of the project, combined with the technology used, mean that this type of facility is much quicker to realise – something which could help to drive opportunities in the UK.

“Financing for the new plant in Falköping, for example, was completed in 2011 and some 18 months later we were already operational and testing,” commented Drew.

“Of course there is more confidence in the Scandinavian market for biomass and CHP but, none-the-less, that is substantially quicker than other large power stations where investment and risk have been bigger hurdles to success,” he continued.

Prior to the construction of the new plant, Falbygdens Energi was said to rely heavily on bio-oil fuel for energy production, but a feasibility study showed that it would make economic sense in the long term to build a completely new cogeneration plant using ORC technology.

Lars Ohlson, CEO, Falbygdens Energi explained: “The main reason for the investment was that we wanted to generate electricity. And we still believe it is cheaper with a hot-oil boiler than a traditional plant with a steam boiler. By investing in small scale bioenergy CHP we can keep security of delivery high, while giving our customers in Falköping eco-labelled energy.”

Technology

The plant was built with technology from Saxlund, a part of international energy and environmental group, Opcon.

Saxlund explained that its team was responsible for all aspects of the turn-key project, from design, construction and commissioning - delivering a biomass power solution that is robust, reliable and almost maintenance free, with minimal staffing.

Key elements provided by the company included the biomass furnace, fuel and ash handling systems, thermal oil system and ORC unit, as well as flue gas treatment and condensation equipment.

The flue gas condenser recovers energy from exhaust gases while a wet electrostatic precipitator removes particulates and ash. The result is said to be a clean-burn, highly efficient power station, with low levels of energy use and very low emissions - importantly CO2 neutral.

Saxlund added that the first major performance tests for the plant have been extremely positive, and in its first year of operation, Marjarp 2 produced some 80 GWh of heating and 16 GWh of electricity.

“In the UK CHP at this scale remains an untapped opportunity, but waste wood fuel and forestry residues are plentiful and the urban density is there to suit district heating projects,” noted Drew.

“We have already built similar projects in the UK and are discussing solutions similar to and smaller than Marjarp 2 which will be especially attractive to on-site industrial heat centres as well as energy producers in the UK,” he concluded.


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