Circular economy is an economic model where production and use are planned so that no waste is created and material and their value remain in circulation. Circular economy aims at developing operation models that minimise the amount of waste created in production processes.
All materials cannot be recycled, for instance, because they are unclean and simply due to a lack of usage of such materials. Recycling products that manufactured with different materials is also challenging. Occasionally materials are also discarded in recycling facilities as so-called rejects. These material flows can be directed to waste-to-energy plants and utilised as energy instead of landfilling.
Energy recovered from waste can be refined into electricity and district heat.
District heat can be used to heat up houses and apartments. Westenergy produces district heat for some 20 000 households.
Electricity is more versatile: with the amount of energy in a single trash bag, one can use oven for 30 minutes, drive an electric car for 20 kilometres or use the vacuum cleaner for an hour!
The amount of electricity produced in Westenergy’s plant covers the annual need of some 12 500 detached houses.
Waste doesn’t disappear completely after incineration but something remains still – ash and unburned material. Larger metal items are separated from the ash already at the plant, and they are recycled.
Ash is delivered for further treatment which means that different sand- and gravel-like materials, that is, so-called minerals are separated and used in the production of different concrete elements and as base material in infrastructure. Smaller pieces of metal are also separated and recycled.
The flue gases of the plant are purified in several stages. First, ammonia-water is added to to neutralise nitrogen oxides. After heat transfer, lime and activated carbon are added as they bind acidic impurities and heavy metals. Next, impurities are filtered out from the flue gases in the fabric filter, and lastly, the flue gases are purified in the flue gas scrubber. Because of the complex purification process nearly all the impurities can be captured from the flue gases.
Environmental permit creates the framework for the plant’s operation, and there are strict emission limits outlined in the permit. The emissions are continuously monitored with accurate measuring devices.
There are about 30 employees at Westenergy. Half of the staff are plant’s operators who work in shifts and control the plant’s operation. In addition, there are, for instance, managing director, environment manager, communications officer, mechanic and waste quality inspector working at Westenergy.
Not everything can be recycled. For instance, products manufactured of several different materials as well as dirty and unclean products cannot be recycled. Instead of landfilling, they can, however, be refined into energy.
Westenergy’s vision is that all those materials that can be reused and recycled are sorted correctly because in this way, materials, energy etc. could be recycled as long and as efficiently as possible.
Due to technological development, more energy can be recovered from waste than before. For instance, in 2019, the flue gas scrubber installed in Westenergy’s plant improved district heating output without increasing the amount of waste. This means that the same amount of waste creates more energy now than before.
Recycling and energy recovery of waste support each other. Energy recovery was invented to fulfill the gaps in waste management: previously combustible waste ended up in landfills where energy and materials were wasted.
Waste-to-energy plants have been designed to utilise mixed materials. Using only plastic would create too high a temperature on the grate and this could cause damages in the equipment and constructions.
There are a lot of different types of plastic out there and not all the types are suitable for recycling. There are also dirty and contaminated plastics that are safer to handle in waste-to-energy plants than recycling facilities or landfills.