Integration of biogas production process into an existing biomethanisation plant

PROJECT DESCRIPTION

BACKGROUND

The BIOGASTIL project targets the problem of increasing greenhouse gas (GHG) emissions together with the low resource efficiency of industrial processes, particularly in biomethanisation. The lack of developed techniques that fully exploit the advantages that biomethanisation processes are able to have on the environment is evident. The AlcoBiofuel (ABF) bioethanol plant, located in Ghent, does not currently produce any wastewater but it consumes a large amount of fossil fuel. As a by-product, the bioethanol plant produces a protein-rich product, DDGS (dried distiller’s grains with solubles), which is used as animal feed. In order to reduce the fossil fuel consumption and the GHG emissions while optimising the plant’s energy yield, ABF will develop an innovative way of producing biogas from treatment of the thin stillage (part of the DDGS). The project aims to integrate the biogas production unit into the existing bioethanol process. The unit will be operational for at least 20 years. The first step has already been taken: the decision to install a CHP unit that will be operational in August 2012.

OBJECTIVES

The overall objective of the project was to develop an innovative means of producing biogas from treatment of the thin stillage (part of the DDGS). The beneficiary aimed to integrating a prototype biogas production unit into an existing biofuel production unit and prove that the technique can be applied by other bioeathanol plants under similar process conditions. This dissemination effect was one of the project's main objectives.

Specific objectives included:

Reduction of GHG emissions through technological innovation;

Substitution of fossil fuels by renewable energy. The project would have produced biogas, a renewable energy source, which would have replaced natural gas;

Maximised energy efficiency and resource efficiency; and

Continuous modernisation and optimisation in existing industrial facilities. The project aimed to encourage the development of innovative renewable technologies and to introduce this method to other existing bioethanol plants.

Expected results: The injection of biogas into the combined heat and power (CHP) installation was expected to save 6.08 g CO2eq/MJ ethanol (in comparison to the pre-BIOGASTIL period, using nominal production values). As well as the increase in efficiency of the CHP by using biogas, the transformation of the liquid thin stillage into biogas would save a considerable amount of energy on evaporating and drying this fraction to recuperate the nutrients. This would result in a reduction of around 9% of the energy used in the dryer.

Other expected results:

BIOGASTIL alone would save CO2eq emissions will be 13 073 tonnes/yr of CO2eq;

CHP + BIOGASTIL would result in primary energy savings of up to 25%, from replacing a steam boiler with a more energy efficient CHP plant and the replacement of natural gas by biogas. This would have meant a saving on primary energy for the production of heat and electricity of nearly 39 000 GJ/yr owing to BIOGASTIL alone. For CHP and BIOGASTIL together, the yearly savings on primary energy would have been 398 015 GJ; and

The project would produce biogas, with an energy content of 173 023 GJ/yr. The injection of this biogas into the CHP plant would strongly increase the efficient use of energy.

RESULTS

The beneficiary withdrew from the project.The beneficiary withdrew from the project.