Biogas Plant, Samso South (proposal)

Fig. 1. Biogas potential (Planenergi 2002).

Samso has a relatively large amount of biomass. Biogas is CO2 neutral and therefore renewable energy. There was a biogas plant (Samsofarmen), but it is no longer in operation. In 2002 a consulting company performed a feasibility study (Planenergi 2001). It proposed several communal plants, wikth the largest covering the southern part of the island. The report named the proposed plant Samso South. It has not been built, but there is now renewed interest on the island, and the government has announced a scheme for subsidies for the period 2010 - 2012 (Green Growth).

Biogas Potential

A communal (central) biogas plant converts animal manure from several farms and other organic material, including municipal organic waste, into energy. Denmark has about 20 communal biogas plants.

Samso has only a small amount of organic industrial waste (Fig. 1). On the other hand the island has a relatively large potential from energy crops in fallow fields and potato tops. Grass, among others, is well suited for a biogas plant.

The largest possible biogas production corresponds to 30% of the energy demand of the entire island (500 TJ per year). The calculation assumes that a central biogas plant produces 35% electric energy, and 50% heat energy; the remainder is for the plant's own consumption and losses.

With the 2008 energy agreement in parliament, the selling price of electricity is now 0.10 EUR (0.745 DKK) per KWH. It is an improvement from the previous 0.08 EUR (0.60 DKK) or lower, and thus a new incentive has arrived. As a consequence of that, the national biogas production is expected to triple by the year 2020. In the period 2010 - 2012 the government intends to subsidise the construction of new biogas plants (Biogasbranchen).

The Samso municipality has already included biogas in its municipal waste plan. It is a facility that extracts gas from the municipal landfill.


A biogas plant offers advantages for waste management, and the biogas plant produces liquid fertilizer and fibre for compost. It has a number of benefits:

  • Lower emissions of greenhouse gases,
  • milder odour than slurry when fertilizing the fields,
  • cost savings in slurry transportation and fertilizer purchase,
  • better use of the fertilizer in a mix of cow and pig manure,
  • fewer nutrients are washed out,
  • weeds and pathogens are killed,
  • waste is recycled in accordance with the national waste plan,
  • there is a tax on waste if incinerated but not if recycled,
  • organic waste in landfill is avoided,
  • heat can be fed into the district heating network, and
  • it contributes to the renewable energy island status.

Even though biogas is renewable energy, it does not necessarily reduce CO2. If for example the biogas is used for heating in the Ballen-Brundby area, the existing district heating plant is already renewable (straw fired), and there will be no CO2 replacement. But the electric production from the biogas plant feeds into the grid and substitutes coal in a coal fired power plant on the mainland; that will contribute to the island's CO2 reduction.

If an animal farmer delivers to a central biogas plant, he might save a slurry tank on his own farm; the biogas company offers the storage and maintenance. A study in Lintrup showed overall cost savings for the farmer at 0.67 EUR (5 DKK) per delivered cubic meter of slurry (Hjort-Gregersen 1999).

The Samso Energy and Environmental Office participated in an EU project Biores with five other islands. The objective was to overcome non-technical barriers that hinder investments in energy production from biogas derived from waste (Biores).

Base Model, M0

Fig. 2. Basemodel M0. Synthetic plant with a daily
treatment capacity of 300 cbm biomass per day
(Nielsen et al 2002).
Fig. 3. Model M1. Actual numbers from Lemvig biogas
plant (Hjort-Gregersen 2008).
Fig. 4. Model M2. Samso South proposal (Planenergi

A study of centralised biogas plants in Denmark established several economic models of biogas plants (Nielsen, Hjort-Gregersen, Thygesen and Christensen 2002). The authors set up three standard sizes of plant. The smallest has a daily treatment capacity of 300 cubicmetres of biomass. We use that as a reference (M0) since it is closest to the proposed plant size.

  • Brancheforeningen for biogas (home page(external link))
  • Lemvig Biogasanlæg amba (home page(external link))
  • Samso Energy and Environmental Office (home page(external link))
  • The Biores project, Reinforcing Investments in Biogas Technologies for Small-Scale RES Applications in Islands (home page(external link))

Created by jj. Last Modification: Wednesday 04 January 2012 22:58:04 CET by jj.