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Ethanol from industrial waste

The Etanolix concept represents a new type of small-scale technology for producing bioethanol for use in traffic fuels that is both easy to set up and use. The first unit to incorporate the new process was commissioned in September 2007 and will play a key role in spearheading St1 Biofuels’ commitment to a distributed production concept for bioethanol.
St1 Biofuels Oy

The Etanolix concept being promoted by St1 Biofuels – a joint venture between energy company St1 and VTT Technical Research Centre of Finland – separates the production of bioethanol from dehydration of the end-product, enabling small, modular units to be located as close as possible to raw material sources.

The process is based on continuous fermentation and associated evaporation, and generates an 85% ethanol/water mixture. Depending on the raw material input used, by-products are suitable for use as animal feed, feedstock for anaerobic digestion, wastewater treatment, or soil conditioning.

An on-site dewatering unit can be installed to further refine the ethanol produced to 99.8% purity, or this can be done separately at a higher-capacity facility. The first Etanolix plant has been configured to produce 85% ethanol, which will be shipped to a dehydration unit around 90 kilometres away. The excellent energy efficiency of this St1 Biofuels-developed unit will also make it economically feasible to dewater other ethanol streams if they are available.

The resulting pure ethanol is then ready for blending with gasoline at an oil terminal and onward distribution to service stations.

Small but cost-effective

The innovative technology behind the Etanolix concept enables plants to be significantly downsized and still be competitive in terms of production costs and energy efficiency when only producing between 1,500 and 2,000 cubic metres of absolute ethanol a year. This compares very favourably with conventional first-generation bioethanol plans, which are typically around one to four hundred times larger.

Due to its modular design, an Etanolix plant can be rapidly assembled from standard parts, without a heavy investment in site infrastructure, while use of the latest automation techniques enables the process to be remotely controlled. The latter enhances the concept’s already low operating costs, as does the income generated by handling and disposing of what would otherwise be worthless waste, and possible by-product sales.

As a result, the concept not only reduces biofuel-related logistics costs, but also those associated with waste management and animal feed production.

Smaller is better

The Etanolix concept provides a new integrated solution to waste management. The feedstock used in the first Etanolix plant consists of bakery waste, reject, and by-products, and the plant is the first anywhere to utilise a small-scale unit to produce ethanol.

Feedstocks containing starch, sugars, or low concentrations of ethanol can all be processed; and product development is under way to extend the range of possible feedstocks to include waste paper, municipal waste, and waste from other manufacturing industries.

Producing bioethanol in this way represents a good alternative to landfills or composting, as these approaches result in releasing the same amount of greenhouse gases without any concrete gain. The amount of carbon dioxide released during transportation is also low, thanks to the reduced requirement for transporting feedstock and by-products inherent in the small unit approach.

The energy needed by the Etanolix process can easily be provided by using residual heat from industrial sites or local renewable sources of energy, such as biogas. This contributes to a lower level of CO2 emissions across the production life cycle, as a result of high energy efficiency.

Ambitious goals for waste-to-ethanol

Following its first Etanolix plant at Lappeenranta in south-east Finland, St1 Biofuels has signed a contract for another plant, at Närpiö in western Finland. This will handle sludge from the local potato industry, which has been verified in laboratory-scale tests as an excellent feedstock for ethanol production.

The Närpiö plant will also be the first to be fully integrated with a customer’s facilities, and will receive its waste input by pipeline. Heat, water, and wastewater utilities will also be integrated with the customer’s processes.

St1 Biofuels hopes to see the Etanolix concept help achieve annual production of absolute bioethanol from waste in Finland reach some 70 million litres by the end of 2011. The potential in other EU countries is even higher, due to their larger populations – and would enable bioethanol produced from biowaste across the Community to rise to more than triple the 1.6 billion litres of bioethanol produced in the EU in 2006.

Modular design means that an Etanolix plant can be rapidly assembled from standard parts, and a unit can be operated from a remote control room thanks to the latest automation technology. The first plant shown here is capable of producing 700-1,000 t/a of 85% ethanol.

St1 operates more than 400 service stations in Finland, over 40 in Sweden, as well as four distribution units in Poland. The company also sells electricity to consumers and smaller companies, and is a large vendor of heating oil across Finland. Aviation fuel is distributed at Helsinki-Vantaa, Tampere, and Vaasa airports.

> Risto Savolainen
(Published in HighTech Finland 2008)