From household waste to biofuel

By Jan Aagaard

Imagine a future where cars are powered by waste, or rather the energy that can be extracted from waste. This could be one of the results of the RE nescience researchproject which the Danish energy company DONG Energy is heading, in collaborationwith waste and energy company Amagerforbrænding and other parties. RE nescience is a new Danish technology, which from initial experiences with a demonstration plant is reckoned to have great potential. The technology transforms unsorted household waste into an energy-rich semi-fluid, which can be used for electricity and heat production, or for producing biofuel. The process also
separates out inorganic materials, which can then be recycled.

Since 2009, RE nescience technologyhas been tested in practice at a pilot plant at Amagerforbrænding in Copenhagen. The household waste is first put into a rotating cylindrical vessel where it is heated to 80-90°C for around half an hour, before being cooled and transferred to another rotating vessel where enzymes and water are added.

After 15-20 hours in the enzyme reactor, all the organic waste is transformed into a brownish energy-rich semi-fluid, while the waste that cannot be broken down by enzymes – plastic, textiles, metal, glass etc – are ejected into a container, making it relatively easy to sort and recycle inorganic waste. The pilot plant at Amagerforbrænding can process around 800 kilos of waste per hour, but the parties involved in the research project are planning a plant that can handle at least 10 times that quantity.

If the technology proves itself to be both environmentally and economically sustainable, it is expected that the first RE nescience plant could be operational by 2020, when it can become part of the new Amager Bakke waste managementcentre.




Storing energy
RE nescience technology has a range of benefits.Among the most important are:Recycling of materials is increased because the process ensures efficient separation of the organic and inorganic components.

The semi-fluid ‘energy soup’ has many uses. Currently there are attempts
being made to convert it into biogas, but it is thought that it can also be
converted into ethanol and methanol, which can be used as a fuel for cars
and other forms of transport. The technology offers the opportunity to store energy. In contrast to the electrical energy from e.g. wind turbines, the ‘energy soup’ is easy to store, which can have importance for the flexibility and supply security of tomorrow’s energy systems.

This article is from focus Denmark Magazine, June 2011