From power plant to refinery

Fortum is studying how it can increase the use of biomass at its plants, including the Rauhalahti combined heat and power plant in Jyväskylä in central Finland seen here. Photograph: Olli Häkämies.

Biomass is steadily becoming an ever-more attractive raw material, not only for the energy and forestry products industries, but for oil refiners as well. There are a number of reasons behind this trend, not the least of which are the industrialised world's concern about the security of future energy supplies and the rising price of fossil fuels.

Above all, however, it is the climate change mitigation-related objectives and the emissions trading that have been introduced in the wake of the Kyoto Protocol that have done the most to enhance the competitiveness and attractiveness of forest and field biomass and waste.

A lot of thought is being given to how biomass can be used as efficiently as possible across a number of industries. One business model that is receiving a lot of attention is the 'biorefinery'. This is analogous to a conventional oil refinery in terms of its ability to produce multiple product streams that exploit as close to 100% of its inputs as possible, with the difference that its products are the fruits of biomass rather than hydrocarbons.

Reflecting this increased interest, Fortum has launched an R&D programme in the area, known as Biogrowth. This is intended to evaluate what biorefinery-related business models and technology could have to offer the company in terms of supporting its sustainable development efforts and future business opportunities.

The new programme marks something of a change of emphasis in Fortum's R&D, which has tended to concentrate on short- and medium-term competitiveness in recent years. The nature of the biomass field, and its undeveloped nature, however, means that Fortum wants to act now and start consolidating its biomass expertise – by building a network of partners and ensuring the future availability of the biomass that it expects to need.

Harnessing all the opportunities

In terms of its future growth prospects, Fortum is particularly interested in integrated plants, where by-products from energy generation are used as the raw material for producing renewable fuels such as biogasoline and biodiesel, as well as pyrolysis oils and chemicals.

One project that is already under way within the company – and in cooperation with a group of universities, pulp and paper companies, and manufacturers – is looking at the possibility of harnessing lignin, from the black liquor that is generated as a by-product in pulp production and is classed as a renewable fuel.

Fortum has developed a number of combustion improvements that make increasing the use of biomass in existing power plant boilers, such as bubbling fluidised bed units, more effective. These enhancements increase combustion efficiency in the lower part of the furnace and reduce fouling and slagging in the superheater and reheater areas, and cut NOx emissions by between 60% and 80%.

As part of the project, cofiring lignin and coal is being tested at Fortum's Värtaverket power plant in Stockholm to generate combined heat and power.

Replacing coal or peat, in whole or in part, with biomass in power plant boilers is not entirely problem-free, however.

To address these issues, Fortum is leading the FORMAT programme – an initiative partly financed by Tekes, the Finnish Funding Agency for Technology and Innovation – which is focusing on modelling combustion and fuel properties. One area of particular study here are the effects different types of biomass have on combustion, fouling, boiler durability, and emissions.

Data from these studies will allow combustion processes to be optimised and maximise the amount of energy that can be generated from the smallest possible amount of fuel, with the smallest possible level of emissions.