Co-firing Biomass with Coal


As nations focus on controlling carbon, global demand for and production of coal-based electricity continues to increase. According to the International Energy Agency, the world’s power demands are expected to rise 60 percent by 2030, with fossil fuels, including coal, accounting for 85 percent of the energy market. Ultimately, building towards a sustainable generation future, means balancing carbon objectives, energy demand and affordability. Biomass co-firing technology can provide a path to addressing climate change while mitigating costs to the world’s coal-generation base and the customers served.
About half of the electricity in the United States is generated from coal. At the same time, the increasing focus on energy and climate change policy in the U.S. has introduced significant regulatory uncertainty in generation planning and operations. This uncertainty around where U.S. carbon policy is headed and when-along with the nature of modern utilities’ complex planning-requires a long-term, forward-looking strategy, one that fully integrates generation portfolio management with changes in demand behavior.
An integrated asset and fuel optimization approach can help the energy industry create a robust strategy set that will stand the tests imposed by constantly changing regulatory requirements, market dynamics, evolving environmental policies and uncertainties regarding timing, funding levels and rate recovery mechanisms.
Co-firing may indeed make sense, from cost and environmental perspectives, for many coal-based electricity producers. Co-firing makes use of existing power generation assets and infrastructure with the lowest cost of generation for renewable energy, while providing a means to mitigate the future cost of carbon. It offers renewable energy generation with low capital costs and takes advantage of the latest technologies and the high efficiencies of today’s coal power plants.
Many national governments provide tax and financial incentives to encourage electric producers to adopt co-firing. In the U.S., where biomass is recognized as a renewable fuel, replacing coal fuel with biomass results in a substantial credit reduction in coal-based carbon dioxide emissions.
Biomass co-firing has been used in Europe for over a decade. Full-scale commercial co-firing of at least 10 percent biomass-based on heat input-is common practice, with a wide variety of bio-fuels and co-firing configurations. The European biomass co-firing market has advanced to the point where the EU is implementing a new certification process for sustainably produced biomass for energy generation purposes. KEMA is assisting in establishing this biomass certification based on the chain of custody-from producer to processors to end-user.
Often electricity producers opt to conduct trials first, to prove the viability, reliability, sustainability and cost-effectiveness of biomass co-firing in their plants. KEMA has been actively engaged in supporting biomass co-firing initiatives already underway in Europe for over a decade, and this technology has been demonstrated in many boiler types. The U.S. can leverage the experience gained in Europe to fast-track implementing biomass co-firing. Complete conversion to 100 percent biomass in a specific unit at multi-unit stations has already proven to be viable and sustainable in certain circumstances. The challenges in the U.S. are around reliable fuel supply and quality, a lack of incentives and a general reluctance by plant operations to introduce new fuels into existing boilers.
We are seeing biomass co-firing on the rise in North America. KEMA has performed feasibility studies on co-firing for a number of large North American utilities looking to assess and quantify the risks, review fuel supply surety and obtain a detailed techno-economic assessment and conceptual design for co-firing of biomass in coal-fired plants. Utilities planning on co-firing between 5 and 10 percent biomass (by heat input) initially have also been interested in knowing what it takes to move towards a 100 percent fuel switch to biomass.
In considering the full fuel switch, utilities are looking to ensure a mix of interrelated considerations, including minimal unit de-rating, no severe adverse operating conditions, no degradation of ash quality, no increase in emissions, compliance with regulation and legislation, broad initial fuel scope and competitive economics/favorable internal rate of return. By using proprietary co-firing control model software, we have been able to facilitate efficient and effective assessment process-providing utilities immediate quantitative insight into the risks associated with firing a mix of fossil and/or biomass fuels in existing coal-fired power plants along with specific guidance to optimize combustion.
As co-firing biomass has become a recognized option in the U.S. electric generation market, biomass co-firing can be a real option in a utility’s portfolio-based approach to climate planning. We have worked with a number of U.S. and European utilities in defining their long-term carbon strategies, the majority of whom are asking to include biomass co-firing as a portfolio option within our sustainable integrated energy modeling tools being employed. This portfolio-based carbon planning process offers another avenue for utilities to assess the impact of biomass co-firing on profit and loss and on the balance sheet along with risk-based scenarios.
Kevin Sullivan is senior vice president with KEMA Inc. and Ronald Meijer is managing principal Clean Fossil Power with KEMA Nederland B.V.

by Kevin Sullivan & Ronald Meijer, KEMA
Published: May 19, 2010