Optimization models to integrate production and transportation planning for biomass co-firing in coal-fired power plants

Abstract

Co-firing biomass is a strategy that leads to reduced greenhouse gas emissions in coal-fired power plants.Incentives such as production tax credit (PTC) are designed to help power plants overcome the financial challenges faced during the implementation phase. Decision makers at power plants face two big challenges.The first challenge is identifying whether the benefits from incentives such as PTC can overcome the costs associated with co-firing. The second challenge is identifying the extent to which a plant should co-fire in order to maximize profits. We present a novel mathematical model that integrates production and transportation decisions at power plants. Such a model enables decision makers evaluate the impacts of co-firing on the system performance and the cost of generating renewable electricity. The model presented is a nonlinear mixed integer program which captures the loss in process efficiencies due to using biomass, a product which has lower heating value as compared to coal; the additional investment costs necessary to support biomass co-firing; as well as savings due to PTC. In order to solve efficiently real-life instances of this problem we present a Lagrangean relaxation model which provide upper bounds and two linear approximations which provide lower bounds for the problem in hand. We use numerical analysis to evaluate the quality of these bounds. We develop a case study using data from nine states located in the southeast region of USA. Via numerical experiments we observe that: (a) Incentives such as PTC do facilitate renewable energy production.(b) The PTC should not be "one size fits all". Instead, tax credits could be a function of plant capacity, or the amount of renewable electricity produced. (c) There is a need for comprehensive tax credit schemes to encourage renewable electricity production and reduce GHG emissions.

Optimal Level of Woody Biomass Co-Firing with Coal Power Plant Considering Advanced Feedstock Logistics System

“…Gubba et al [15] suggested level of straw co-firing of 12% on thermal basis using particle heat-up model. However, only a limited number of studies have dealt with the logistics costs to estimate co-firing ratio [17,18]. Berggren et al [17] developed a cost optimizing linear programming model to investigate the potential for co-firing of biomass and coal in the Polish power-generation system.…”

“…Key parameters used in their model included boiler retrofit cost, operation/maintenance cost, and fuel cost, including transportation cost. Eksioglu et al [18] proposed a model that integrates production and transportation planning to estimate optimal biomass co-firing ratio in coal power plant. While their mathematical models integrate plant operations with transportation-related decisions and thus assist on co-firing decisions, they exclude various logistics options for biomass procurement, such as multimodal transportation.…”

“…The PTC is currently equal to $0.012 per kilowatt hours of electricity generated by open-loop biomass which includes any agricultural livestock waste nutrients, or any solid, nonhazardous, cellulosic waste material [29]. However, PTC for general co-firing is not clearly specified [18]. In this study, we extend PTC to support biomass co-firing with existing coal power plants in the Great Lakes States area and estimate the impacts on co-firing ratios.…”

“…In our study, a 1% drop in conversion efficiency for every 10% of mass increase in co-fired biomass is assumed [30,31]. In addition, the maximum ratio of biomass co-firing is limed to 50%, as it is known that the high ratio of biomass co-firing can significantly increase the slagging, fouling, and corrosion in the boiler [7,18]. The 50% maximum ratio for co-firing also restricts the loss of boiler efficiency to maximum 5%.…”

Advanced Woody Biomass Logistics for Co-Firing in Existing Coal Power Plant: Case Study of the Great Lakes States

“…Feedstock Supply Network: Origin and Destination. Though various types of biomass can fuel co-firing power plants, forest and mill residue were used for this research, as they produce low sulfur and chemical levels (16) and are widely available in the study region. Furthermore, a potential recovery in the U.S. housing and lumber markets could increase the availability of sawmill residues (23).…”