Optimum cycle

We all want to handle raw materials and energy more consciously. We separate our green waste from the rest, put glass in the glass recycling container and set our heating a degree or two lower. Every little bit helps. How does Twence contribute to this? And what makes Twence a source of sustainability?

By focussing on the usefulness of the output and not just the waste stream, and by considering the entire chain we can help find the right balance between climate and sustainability objectives on the one side and returns on the other. Our source, the raw material ‘waste’, must deliver the best (residual) products in terms of reusability and energy. Whether it is compost or bottom ashes, manure or construction debris. At Twence we provide for the best possible cycle.

Sustainability is in our blood at Twence. We do not sit and wait, but take the lead. We want to contribute to a society that gives serious thought to creating a better environment for future generations. One way we implement this is by producing renewable energy from biomass, thus eliminating the need to use fossil fuels. We are building solar parks so that we can make good use of the most direct source of energy we know. We also make use of non-renewable waste to generate energy.

We want to keep raw materials and goods in the cycle in such a way that they retain maximum renewability. This can be done by considering not only the waste stream but the entire chain, by continually exploring the latest insights and working with state-of-the-art technology. We have the long-term perspective and future generations in mind when we make our decisions. For us it means that we also put a lot of energy into education, by giving excursions and getting young people interested in technology. In these and many other ways we put our knowledge to optimum use so that we can ultimately achieve a circular economy.

Twence originally started as a landfill site, but is now a source of sustainability. By making conscious decisions and purposeful investments based on our role in society, we lead the way where the energy transition is concerned.

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Our sources

Smart plants recover the maximum from substances which society cannot use again without processing and regards as waste. Twence converts recyclable waste, biomass and non-reusable refuse-derived fuel into reusable component streams, compost, raw materials and energy. In addition, we produce energy from sunlight.

Recyclable waste
In our materials recycling facility we process construction and demolition debris, dry commercial and industrial waste and oversized municipal solid waste into reusable component streams such as metals, wood, demolition waste, sand and high-calorific waste. We use materials which are not reusable after separation but which are combustible, as fuel in our energy from waste plant or – for example if it is wood residue – as fuel for the biomass power plant.

Organic material, including wood, organic waste from kitchens and gardens, material past its use-by-date and manure, serves as the raw material for the production of 100% green electricity. Biomass is the collective name for these materials. The organic material from businesses and households is processed into biogas in our anaerobic digesters. In a second step, our composting facility makes compost from the digestate. We convert waste wood and other non-renewable organic waste into renewable electricity in our biomass power plant.

Combustible non-recyclable waste
Municipal solid waste is a collective name for the waste which arises from the normal operation of a household. Households are stimulated to already separate the reusable part of their waste at the source, for example glass, old paper and cardboard and plastic. This leaves combustible, non-recyclable waste. A similar waste stream can arise at businesses. We process this waste into electricity and heat with an extremely high level of efficiency in our energy from waste plant.

Tens of thousands of solar panels on and close to our main site at Boeldershoek in Hengelo absorb sunlight and convert it into green electricity. Solar parks tie in with our efforts to extract more energy from renewable resources. Starting in 2020, the next solar park – our third – will be constructed on top of the former landfill site ‘t Rikkerink in Hof van Twente.

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Reusable materials

In addition to energy, Twence also produces reusable metals, bottom ashes, compost and recycle streams.

Incineration leaves behind bottom ashes which still contain many reusable metals. We remove more than ninety percent of the ferrous metals and more than eighty percent of the non-ferrous metals from bottom ashes, such as aluminium, zinc and copper. We can thus return metal particles down to the size of a pin-head to the cycle. These metals are sorted by specialised processing companies according to type and made suitable for reuse.

Bottom ashes
Bottom ashes are the non-combustible residue left on the burner tray after combustible (residual) waste has been incinerated. Once the metals have been removed, bottom ashes can be put to useful applications in different ways. They can be mixed (and stabilised) with cement-like materials, creating a strong and stable secondary construction material which can be used freely, for example as foundation material for road construction. This material was used for the foundations of the latest extension of the CTT container terminal on the canal in Hengelo. Bottom ashes which are not stabilised can be used if they are isolated according to the ICM criteria (Isolate, Control, Monitor). For example, these bottom ashes can be used as filler for dike bodies or sound barriers, and similarly as base material for road construction.

Our bioconversion plant uses anaerobic digestion reactors to produce energy from mainly organic waste from kitchens and gardens of businesses, homes and municipalities. We process the digestate (the material left after anaerobic digestion) into high-quality compost. Compost is used as a soil enhancer in the agricultural and horticultural sectors and by private persons, but also as a replacement for peat in the potting soil industry.

Recycle streams
The materials recycling facility at Twence separates construction and demolition debris and oversized MSW into reusable component streams:
•    Paper and cardboard
•    Wood
•    Demolition waste
•    Metals
•    Carpet
•    Plaster
•    Plastics/foil

The component streams from the materials recycling facility are prepared by external parties for reuse.

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