Measuring Efficiency – The Heat Is On!
EnergyLines February 2019
Heat rate measures the efficiency of the units at the Merom Generating Station to convert energy (BTUs of energy from coal) to megawatts of electricity. Heat rate is similar to the gas mileage of a car, except that for a car, higher numbers indicate efficiency – going more miles on fewer gallons of gas. At the Merom Generating Station, a lower number is better.
The operations and engineering staff concentrate on improving performance in three areas to ensure the plant is efficient and competitive in the electric market. These areas are:
THE BOILER: Reviewing how the boiler (car) is consuming coal (gas).
THE TURBINE: Coal is used to heat water producing steam, which turns the turbine and generator to create electricity. Wasted steam means lower efficiency. (It’s like leaving your car running means lower miles per gallon.)
THE AUXILIARY LOAD: This takes into account how much of the electricity generated is actually used by the plant. This includes electricity required to run pumps, mills, environmental controls, conveyors, heaters, office HVAC, lights, etc. (How much gas it takes to run your car’s air conditioning, charging system, water pump, etc.)
To make sure the plant is running smoothly, routine maintenance is performed throughout the year, including scheduled maintenance. This is akin to getting an oil change, tune up and rotating the tires on your car. Performance tune-ups are often conducted in the spring.
- Turbine and steam valves are rebuilt to ensure steam is being utilized efficiently.
- The condenser is cleaned so that the steam can be condensed and the plant can control the steam pressure in the turbine for the desired loads.
- Auxiliary equipment is maintained and updated so that it consumes the least amount of the produced electricity.
Another aspect for improved heat rate is high capacity factor. The units are designed to run at full load and stay there for optimum performance. This is similar to a car being on the highway with the cruise control set. When units have to ramp up and down, it is similar to stop-and-go traffic or city driving in your car – efficiency is reduced.
The asset management team and power marketing group work together to identify projects that will best match unit performance with market conditions to meet station goals. It is like needing a car to go from a daily highway driver to a stop-and-go urban driver. Those requirements need to be evaluated for the critical equipment and then changes will need to be made. While the changes must be realistic (difficult to turn a quad-cab pickup truck into an electric car) it is worthy to note that changes can be made to make Merom Generating Station run more efficiently.
As part of the process to ensure ultimate heat-rate efficiencies, management for the generating station has researched several options to help with improvement.
In 2017, Hoosier Energy contacted a vendor that has been collecting data on the operating units for several years, with the goal to benchmark the heat rate performance and establish a continuous improvement program.
The software was launched in 2018 in conjunction with the start of a continuous-improvement program. Each operational shift was made aware of its performance versus the baseline and then was asked to record its results.
The software establishes a baseline of target efficiencies for approximately 12 operator-control parameters based on the average performance over the last two years of operation. It displays these parameters, on an accessible software screen. This program compares the performance of each shift versus the established baseline.
After several months, it was discovered that the operational changes resulted in exceeding the historical performance on the controllable parameters by a projected $1.5 million for the year.
The station plans to keep adjusting the baseline according to each year’s performance in order to foster continuous heat-rate awareness and improvement, thus providing the members with the most efficient, reliable and competitive power the Merom Generating Station can produce.