What is energy?
Energy is what a living being or machine needs to be able to do anything. In physics, energy is expressed in joules or calories. One calorie is the amount of labour required to make 1 gram of water rise 1 degree Celsius in temperature.
The largest source of energy we know is the sun. Growing plants store a small part of that energy. With fossil fuels such as coal, oil or natural gas, that already happened millions of years ago. When we light the gas now, we actually indirectly receive solar heat from millions of years ago.
The use of fossil fuels must be reduced, and the circular economy (the reuse of raw materials) is also progressing. Twence contributes to this by achieving optimum efficiency from all available sources.
Energy from waste plant
The waste we process – waste material made from fossil fuels as well as material made from plants and trees – has solar energy ‘caught’ in it. When we incinerate that waste, the energy stored in it is released in the form of heat. The walls of the incinerator contain a network of pipes filled with water. That water becomes so hot that it turns into steam. We use the steam to drive a turbine. It is connected to a large generator which produces electricity. We supply the electricity to the public grid so that businesses and households can use it. Coal-fired or gas-fired power plants make electricity the same way. We can also use the heat of the steam directly for industrial applications and for heating houses.
Because electricity and heat are needed every moment of the day, the energy from waste plant operates 365 days a year, 24 hours a day. We only switch the three incineration lines off for maintenance work, in turn, at specific times.
R1 – useful application
Thanks to its supply of heat, steam and electricity, the Twence energy from waste plant has achieved R1 status from the government, the status of ‘useful application’. This means we convert the processing heat created in our plants very efficiently into energy carriers. Only the best European plants with high environmental and energy performance are eligible for the R1 status.
54% of the energy produced by an energy from waste plant is deemed to be sustainable, due to the proportion of biogenic material that is still present in the ‘grey’ waste.
Dutch energy from waste plants supply 15% of the renewable energy production in the Netherlands. In technological terms, the Dutch power plants are among the most advanced in Europe. The share of renewable energy of the total energy consumption in the Netherlands is currently approximately 4 percent.
Biomass power plant
In the biomass power plant we do the same as in the energy from waste plant. Here too, the boiler walls have pipes filled with water which convert the heat of the fire into steam. However, the fuel we use here is waste wood. Because it does not contain material made from fossil fuels, this electricity is deemed to be 100% green.
In the coming years we are converting our biomass power plant so that we can use it to supply heat as well. This will treble the energy yield of the power plant from approximately the same quantity of fuel. And all of that is 100% green and sustainable.
For more information about this BEC2.0 project, click here.
The green waste bin is already a small gas plant in itself. Organic waste from kitchens and gardens rots. This creates gas. The same thing happens on a large scale in Twence’s anaerobic digesters. The bioconversion plants process organic waste from kitchens and gardens from businesses and homes, as well as green waste from municipalities and material past its use-by-date, into biogas.
Living organisms in large, enclosed vessels cause the biogas methane to form in the waste. Gas engines convert this biogas efficiently into electricity and heat, which we supply to several thousands of households.
The residual waste from the anaerobic digester is composted. Thus we put this material to good use twice in a row.
Waste from previous generations also still produces energy. It was only a few decades ago when all waste was dumped in landfill. That waste contains all kinds of material of vegetable or animal origin: organic waste. When that waste starts decomposing, gas is formed. We capture that gas and use it to generate electricity and heat. By keeping our landfill gas plants in good condition, we continue to supply electricity and heat from landfill gas to hundreds of households close to the landfill sites we manage – ’t Rikkerink (Ambt-Delden), Elhorst-Vloedbelt (Zenderen) and Boeldershoek (Hengelo).
These days we only dump waste in landfill that really cannot be reused or incinerated. In practice this is only a fraction of the materials that enter Twence over the weighbridge.