Crude glycerine water used on-site as a feedstock in an anaerobic digestion reactor to produce the renewable fuel biogas

PROJECT DESCRIPTION

BACKGROUND

The oleochemical industry is an important sector of European industry that produces a variety of high-value chemicals from renewable sources. These sources can be vegetable based (rape oil) or animal based (animal fat). In each case crude glycerine is produced as a by-product of the production processes. To be able to sell this by-product producers need to refine it into pure glycerine. Pure glycerine in itself is non-toxic and non-irritating with no known environmental impact. It has over 1500 known end uses in cosmetics, toiletries, personal care, drugs and food product. However, the processing necessary to achieve pure glycerine is very energy and water intensive. On top of consuming high amounts of energy for the refining process and transportation and water, the process also requires the bleaching and cleaning of processing equipment using aggressive chemicals such as phosphoric acid and caustic soda. The waste produced during the procedure is either discharged into surface water or dumped in old salt mines. In addition, the demand for pure glycerine is low compared to the amount of crude glycerine available and this means it has now become a low-value by-product in danger of becoming a waste product. As such the process of refining glycerine is unsustainable both environmentally and economically.

OBJECTIVES

The aim of the QUARTERBACK for LIFE project was to reduce the environmental impact of the production of crude glycerine and respond to the problem of the increasing worldwide glycerine surplus. It did this by demonstrating in a full scale application the technical and economically feasibility of turning the glycerine produced by the oleochemical industry into biogas that can be used on-site to replace natural gas.

Specifically, the project sought to operate an integrated process which used process water containing 15% glycerine as the sole feedstock for an anerobic digestion process to make the plant’s Combined Heat and Power (CHP) unit more energy efficient and ensure substantial water and electricity savings. Thanks to these process improvements the project aimed to develop an innovative integrated process allowing oleochemical facilities to stop adding to the worldwide glycerine surplus and fuel part of their energy consumption with a carbon-neutral biofuel thus reducing their emissions.

RESULTS

The QUARTERBACK for LIFE project successfully demonstrated the feasibility of operating an integrated process in which oleochemical facilities could use process water containing 15% glycerine as the sole feedstock for an anaerobic digestion process. This allowed to produce biogas for local use. The biogas produced on-site replaced the use of natural gas and generated approximately 10% of the energy demand.

Since the water containing the 15% glycerine was used for anaerobic digestion there was no longer a need to process it on site by evaporation thereby saving a substantial amount of energy and water. Not processing the glycerine also means a reduction in the use of corrosive chemicals.

The application developed by the project also improved the overall conversion efficiency of the plant’s CHP unit by allowing its boiler and gas engines to run partly on the biogas produced from the anaerobic digestion of glycerine. This led to further energy savings.

This ground-breaking and unlike any other project was the first full-scale demonstration of the use of crude glycerine water to produce biogas. By using crude glycerine water in this application oleochimical facilities no longer have to go through the energy intensive steps required to convert this type of water into pure glycerine.

The Quarterback for Life project is also the only one of its kind that included consideration of the effluent discharge (i.e. the waste water discharged into a river or the sea) through water treatment. By improving the aeration and mixing aspects of effluent treatment the project reduced electricity usage.

These modifications significantly improved the sustainability of oleochemical facilities as well as their profits (using waste glycerine as biofuel is more interesting financially than processing it and selling the resulting pure glycerine at reduced market rates). This is expected to lead to growth, investment and job creation. Other local social benefits include the reduction of noise and odour emissions, avoidance of road and waterway transport of crude glycerine and improved social awareness of environmental issues. Overall, the methodology holds high replicability potential.

Significantly, the project also supported a range of EU policies such as the 2030 EU Climate and Energy Policy Framework, the Energy Roadmap, the Renewable Energy Directive ( 2009/28/EC), the Water Framework Directive (2000/60/EC), the Industrial Emissions Directive (2010/75/EU) and the Waste Framework Directive (2008/98/EC).

Some key results and benefits include:

A reduction in emissions of 10,852 tonnes CO2/year in 2017 and expected to reach 12 000 tonnes/year by 2018;

A 41% reduction in groundwater extraction in 2016 and expected to transition to zero m3 by the beginning of 2018. Salt discharge is expected to be directly correlated with groundwater extraction;

A 13.8% reduction in electricity consumption achieved in 2016 and expected to reach a 16.5% reduction by early 2018;

A 54% reduction in glycerine water evaporation and a 10.2% reduction in feedwater to the boiler;

A 56% reduction in noise and odour complaints between 2014 and 2016.

Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).