Processing biomass
By the term biomass, we mean organic waste streams derived from animal and plant remains. We process these into new raw materials and sustainable energy. How does this process work? And what kind of facilities do you need for this?
How we process biomass
We process biomass at Twence. That is to say: organic waste derived from animals or plants. Examples include waste wood, wood fibre, sawdust residue, vegetable, fruit and garden waste (VFG) and manure. We process these into products such as compost, soil enrichers, artificial fertiliser substitutes, pyrolysis oil and sustainable energy. We can also sell clean waste wood for recycling as a material.
Biomass comes to us in a variety of ways. Each type of biomass stream goes to a specific processing plant. We use a variety of facilities to process biomass. You can see at a glance in the graph below which biomass is delivered to us, which plant it goes to, what we make out of the input and who we ultimately supply the new raw materials and energy to. Next, we give a brief explanation of each facility.
Empyro: making pyrolysis
We produce pyrolysis oil, electricity and steam in the Empyro pyrolysis plant. The raw material for this plant is sifted from pellets for wood-burning stoves (a type of biomass). Oil is produced by applying extreme heat for a short period of time to the biomass. This process is called pyrolysis. From every 1,000 kg of biomass, we produce about 650 kg of oil using this method. The combustible gases released during pyrolysis are used to produce electricity and steam. We supply this low-pressure steam to the salt producer Nobian, right next door to Empyro. FrieslandCampina Ingredients uses the pyrolysis oil as green energy in the condensation process for evaporating liquid milk into whey powder ingredients at the factory in Borculo. This means a reduction in the consumption of natural gas. The energy supplied to FrieslandCampina and Nobian is comparable to the natural gas consumption of 8,000 households.
Composting and fermentation
The green waste container is actually already a miniature gas factory. Vegetable, fruit and garden waste (VGF) starts to rot. This process yields biogas. The same happens on a larger scale in the anaerobic digesters at Twence. In the composting and fermentation facilities, the VGF from businesses and households is pre-processed and converted into biogas, along with expired foodstuffs from supermarkets and other sources. In large sealed tanks, living organisms cause biogas to form. Gas engines then efficiently convert this biogas into electricity and heat, which in turn provides several thousand households with sustainable energy. The residual material from the digesters, digestate, is composted together with green waste from municipalities and the coarse fraction of VGF that was separated earlier. Keurcompost is used as a soil enricher on agricultural land. We process the wood fraction that remains after composting and fermentation into sustainable energy at our biomass power plant.
Biomass Energy Centre (BEC)
Waste wood that is sorted from bulky household waste and construction and demolition waste at our separation plant goes to the biomass energy centre (BEC). Just like the waste-to-energy plant, the BEC uses a grate furnace and a steam boiler for energy production. The boiler walls are lined with water-filled tubes that convert the heat from the burning biomass into steam and hot water. We also use it to generate electricity via a steam turbine/generator. At the biomass power plant, we process non-recyclable painted and glued waste wood as fuel. As this does not contain any material derived from fossil fuels, this energy is considered 100% sustainable and green. We supply the electricity, steam and hot water as sustainable energy to companies and households in the region.
What happens at the Biomass Energy Centre (BEC)
Manure valorisation plant
Manure contains lots of water and is full of energy and raw materials, including the minerals phosphate, potassium and nitrogen. We use our facility to recover those valuable raw materials and energy from the manure. The manure delivered goes to the anaerobic mono-manure digester, where we capture the biogas and convert it into green gas. Next, the fermented fraction goes to the flotation separator where the thick fraction is brought to the belt filter press. There, even more thin fraction is extracted from the manure. The thick fraction that remains is called phosphate fertiliser and is used as a soil enricher. The thin fractions are upgraded to potassium fertiliser and nitrogen by means of membrane filters and an evaporation process. The former is used to make fertiliser substitutes and the nitrogen finds its way into industrial applications as an ammonia solution. On top of that, we return clean water to the surrounding brooks, supply green gas that can be used to heat 3,000 households, and deliver CO2 as a growth medium for greenhouse horticulture.
And this is what we make from biomass!
