Chips + sunshine slash heating costs by 75 percent

Oct. 21, 2010

“Always start by making your buildings more energy efficient before you buy a heating system based on bioenergy.”
The advice came from Nils Tunströmer during a study tour as part of the World Bioenergy conference and trade fair in Jönköping, Sweden.

Tunströmer and his company, NT Energi, presented a newly installed heating system that has reduced energy consumption by 50 percent and cut costs by 75 percent with the aid of solar panels and wood chip incineration.
The system is at the Iris drug addiction and therapy centre in Mullsjö north of Jönköping. A planned expansion of the facilities also led to the decision to invest in a new heating system with the aim of reducing both the cost and the environmental impact. The centre is owned by a not-for-profit foundation and any surplus money is reinvested in the business.
Currently the centre consists of a main building, six houses and a greenhouse. Previously these were heated with oil and electricity. Consumption was about 450 MWh/year and the power rating of the heating system was 200 kW.

Halved the power rating
“The first measure was to make the buildings more energy efficient,” Tunströmer says. “That allowed us to halve the power rating and thereby reduce the investment cost of the new heating system.”
In practice the power rating became the same size as before, because the system was dimensioned to cope with any future expansion of the treatment centre.
The primary energy source consists of solar panels on the roof of the new boiler building. These generate 30,000 kWh per year. The heat is stored in accumulator tanks and is enough to supply hot water during the summer months. During the rest of the year most of the heat comes from a 200 kW wood chips boiler.

New purification technology
“The centre’s philosophy is that everything used in its operations should be locally produced – even the wood chips,” Tunströmer said.
Another aim of the investment programme was to reduce the environmental impact. To keep even this as a local project, the supplier of the wood chips, the Finnish company Ariterm, cooperated with Linnaeus University in Växjö.
During the study visit, Henrik Karlsson of Ariterm demonstrated the particle filter that resulted from the joint venture. The filter ionises the flue gases and reduces the amount of even the smallest particles by more than 25 percent.

Payback in ten years
Work to develop the filter is continuing and the goal is to achieve a considerably higher purification level. This would make chips incineration better for the environment than other forms of energy, even for the local residents.
Iris has invested SEK 3.5 million, which includes making the buildings more energy efficient, digging culverts, constructing the boiler building, and so on. At today’s energy prices the payback period is ten years.
The centre’s heating costs have been greatly reduced: the energy needs have been halved and then the switch to solar power and wood chips has halved the costs. The result is that the new energy system heats the treatment centre 75 percent more cheaply than was previously the case with oil and electricity.