Small-scale CHP from biomass

A demonstration project in south-east Sweden has been setup to highlight three different techniques for small-scale biomass-based cogeneration

The project – called Small-Scale CHP LIFE+ (2014-2019) – is financed jointly by the EU Life+ programme and the Swedish Energy Agency. It has multiple aims:

  • Demonstrate three technologies
  • Create a platform for small-scale CHP by arranging study visits
  • Increase the use of small-scale CHPs
  • Disseminate the experiences from running the technologies
  • Increase local and renewable electricity generation and thereby decrease CO2 emissions.

The three technologies

The project is highlighting three different technologies for small-scale biomass-based cogeneration: Gasifier, Wet Steam Turbine (WST), and Organic Rancine Cycle (ORC).

The three demonstration sites

Emåmejeriet (Emå Dairy) is a local producer of milk and dairy products in Hultsfred. The plant is owned and run by the farmers themselves. They have a strong local and environmental profile with their slogan “Milk from your area”. They have installed a gasification plant where the wood is converted into heat (100 kW) and electricity (40 kW). The process also generates biochar (500 l/week).

The choice to switch from an oil-based heating system to a gasification plant is due partly to reduced tax relief. It is also to meet the company’s and consumers’ growing environmental demands. The existing heating system was also in urgent need of refurbishment.

Ronneby Miljö & Teknik AB is a local energy company that supplies heat, sanitary and water. They have installed a Wet Steam Turbine at the Sörbyverket district heating plant. The turbine will generate 500 kW electricity which will be sold to the electricity grid.

A Wet Steam Turbine is relatively easy to implement. The upgrade takes place in the boiler water circuit without extensive reconstruction of the boiler. Compared to conventional steam turbines, a Wet Steam Turbine can operate at lower pressure and lower temperature. It’s a more robust and a less high-efficiency turbine which unlike conventional turbines can even handle some water particles.

Here’s a video of the installation of the Wet Steam Turbine at the Sörbyverket district heating plant:

Ronneby Miljö & Teknik AB has also installed an ORC turbine at the district heating plant in the village of Bräke-Hoby.

ORC technology is based on a closed-circuit turbine driven by an organic working fluid with a boiling point that is lower than water. The plant generates electricity by utilizing the hot side of the boiler circuit and the cold side of the district heating network. Via the circuit working fluid (with a low boiling point) the ORC plant can generate electricity at a lower temperature, in comparison to conventional power plants. This makes the technology well suited for production of green electricity from biomass in smaller district heating or local heating plants.

Here’s a video of the installation of the ORC turbine at Ronneby Miljö & Teknik AB:

Make a study visit

All three sites are open for study visits. This will give you the opportunity to learn more about small scale combined heat and power production and see these three different technologies in practice.

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