Co-firing Biomass, Sewage Sludge and Municipal Waste is Hot Topic on March 17, 2011

Although a renewables-only mandate failed to pass during the last Congress, there is still considerable discussion and interest in legislating a clean energy standard (CES), which would require utilities to generate a portion of power from sources that emit less carbon emissions, like solar and wind, but also nuclear, coal with carbon capture and sequestration, natural gas and biomass. More and more states are leading this effort by enacting Renewable Portfolio Standards (RPS) that mandate the role renewable fuels will play in power generation. Also, in his State of the Union, President Obama proposed a "clean energy" measure, calling for the country to produce 80 percent of its electricity from clean energy that includes biomass by 2035.

As a result, utilities are increasingly looking at co-firing biomass to meet the mandates of states for providing a percentage of power from renewable sources in the near future but also because of the potential to reduce CO₂ emissions to meet anticipated GHG regulations.  However, there are problems with biomass such as the lower energy input, compatibility with other equipment particularly boiler feed systems, availability of suitable biomass materials and other supply chain challenges.

The following speakers will address the issues and implications of converting coal-fired power plants to full or partial use of biomass, sewage sludge or municipal waste, the biomass fuel choices and how these vary regionally, the costs that need to be considered in a biomass conversion plan, the advantages and disadvantages of various fuels, methods for co-firing and available equipment options and to describe their experience with co-firing of biomass, sewage sludge and municipal waste at utility boilers.

Dr. Desmond Smith, Ph.D. Vice-President at BRUKS Rockwood, Inc., will discuss biomass handling and preparation prior to co-firing. Co-firing wood and biomass with coal in a suspension burning boiler requires that the fuel be prepared in specific ways to be effective in the way it performs.  Conventional coal preparation machinery does not process biomass.  It is necessary to control moisture to allow the machinery that grinds the organic fuel to produce a finely ground product that can be transported and injected pneumatically.  Several natural factors that are inherent in biomass' natural state must be taken into consideration, and in some cases modified, for the entire process to proceed reliably and effectively.

Dr. Fernando Preto, Senior Scientist and Group Leader for Biomass Conversion at CANMET Energy Technology Centre, will discuss the co-firing of lignite with wood (pine) residues and peat focusing on emissions and ash deposition. His presentation will review the effects of fuel blending ratios, excess air, and moisture content on air emissions (CO, SO₂ and NO_x) from co-combustion of wood residues and peat with lignite.  Co-firing leads to significant differences in the concentrations of some major inorganic compounds (e.g. SiO₂, CaO, MgO, SO₃) in deposited ashes. The effects of fuel ash composition, principally alkali and alkaline earth metals and halogen elements on ash deposition rates and deposit properties (e.g. corrosivity) will also be reviewed.

Kevin Toupin, Director, Boiler Equipment, Babcock Power, Inc. / Riley Power, Inc.

To register for the “Hot Topic Hour” on March 17, 2011 at 10 a.m. CDT (Chicago time), click on: http://www.mcilvainecompany.com/brochures/FGDnetoppbroch/Default1.htm.