Richard Larmour, BSc(Eng), C.M.V.P.
Energy Efficiency Engineer
University of Cape Town
This presentation has resulted from a Master’s degree dissertation which aimed to develop a credible Measurement & Verification (M&V) methodology for a coal fired power plant (CFPP) in South Africa. The plant underwent an extensive refurbishment programme over several years with the aim of improving the heat rate by at least 1%. The programme consisted of multiple projects including major equipment repairs, replacements, refurbishments, operational optimisations and measures to reduce auxiliary power use. The utility required that the efficiency impacts of the projects be quantified using M&V, a method which is commonly used for finding the impacts of demand side energy conservation measures (ECM). In the USA it is estimated that over the last five decades CFPP efficiencies have declined by several percent for reasons including reduced maintenance, increased cycling operations, declining coal quality, decreased personnel levels and the installation of emission controls (EPRI 2014: 1.2, 1.3). The benefits of improving efficiency include reduced operating costs, reduced emissions, extended life of coal reserves and potentially increasing power output (IEA 2010: 15). A sound M&V methodology will allow plant operators to gain a quantitative idea of the real energy and power impacts of the refurbishment programme versus expected theoretical impacts, and will provide the basis for a realistic cost benefit analysis to guide future investments. The purpose of M&V is to isolate the changes in energy use which are attributable to specific ECM’s from changes due to other factors. This is achieved by constructing an adjustable energy baseline that characterises energy use as a function of significant energy drivers. This makes it possible to estimate what the energy use would have been in the absence of any ECM’s. CFPP’s are large, complex facilities and there is no single universally accepted method for determining and expressing the real operational heat rate (IEA 2010: 15). Different methods use different assumptions, measurement bases, measurement boundaries and assessment periods. This case study has been used to develop an M&V methodology which is guided by the constraints of costs and data availability. The paper evaluates the merits of various measurement boundaries and examines the significant fixed and variable factors affecting calculated CFPP heat rate. The challenges of measuring coal consumption and coal heating values are also explored. An M&V methodology is proposed which includes a suggested measurement boundary and assessment period, a multi-variable baseline heat rate adjustment model, important assumptions required, reporting uncertainty, a sensitivity analysis, a discussion of the limits of applicability of the method to CFPP’s in general, and makes recommendations for future studies.
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