Fortum Värme, a company jointly owned by Finnish energy firm Fortum and the city of Stockholm on May 9 inaugurated a new biomass-fired combined heat and power (CHP) plant on the shores of Värtan, a strait in Sweden’s capital city.
The Värtan CHP8 (130 MWe, 280 MWth), which began construction in 2013, will begin commercial operations in the fall (Figure 5). According to its developers, the plant will use forest residues and wood waste—sawdust, bark, and logging residues from local and regional sources around the Baltic Sea—as well as recovered heat from data centers to produce district heat for nearly 200,000 households. The plant is also designed for fuel flexibility to allow it to use new fuels from the developing bioenergy market, Fortum said. Daily consumption of wood chips will be about 12,000 m3.
Building the plant in the middle of Stockholm—a city with a population of about 1.4 million people—involved multiple challenges, including working with limited space and requiring closed-fuel systems to avoid dust emissions and noise. The plant uses an old rock cavern—previously used for oil storage—that was converted into a massive underground wood chip storage facility. It is able to store about 60,000 m3, or five days of fuel demand.
While the Värtan site has full access to road, rail, and sea transportation, the current fuel procurement plan is based on getting 40% by rail from Nordic biomass suppliers and another 60% by ship from the Baltic Sea region and Russia. “The aim is to ensure the security of supply and access to a wide geographic biomass market over time,” Fortum explained.
To ensure adequate supply by sea, the company built a new 200-m pier in the harbor area to accommodate two vessels up to Panamax size. On average, the plant requires three to four shipments per week to meet its fuel demand, as well as five trainloads per week, each with a capacity of about 4,600 m3. All fuel is unloaded and processed indoors within a closed system before delivery to the power plant. All logistics are coordinated in-house to control supply risks.
The company’s decision to use biomass was complicated by an emerging debate in the European Union (EU) about how sustainable the fuel source is. Fortum noted in an April 2016 energy review that biomass is now the most common form of renewable energy in the EU, and it is the only source that can replace every type of fossil fuel in all energy markets—heating, cooling, electricity, and transport—but concerns are growing about competition for resources and security of supply.
In the EU, while sustainability and traceability concerns are primarily related to biomass imports from other continents, the 27-member bloc has yet to issue a uniform sustainability policy on all bioenergy (current EU sustainability criteria only apply to biofuels and bioliquids, not solids), and that has hindered investments in biomass. “Harmonised sustainability criteria for all bioenergy would increase the predictability and stability of the operating environment, ensure proper functioning and transparency of the biomass markets, increase the use of sustainable biomass in energy production, and promote the transition from fossil fuels to renewable and carbon-neutral biomass fuels,” the Fortum review added.
The EU’s policy, which is currently under public consultation, should apply to the origin of all bioenergy regardless of end use, be legally binding, and be applicable to plants exceeding 20 MWth. Ultimately, it should enable increased use of biomass while minimizing administrative burdens or related costs. “The new criteria should not decrease the competitiveness of biomass: in many cases, biomass competes with fossil fuels, which generally have no requirements to demonstrate sustainability,” it said.
—Sonal Patel, POWER associate editor.