Generators could keep water and sewer plants running in emergency

Before Bob Stevenson retired recently as general manager of the Hannibal Board of Public Works (HBPW) he was able to scratch one more thing off of his “to do” list — declare the HBPW’s diesel generator project was completed.

“It turned out being way more (work) than we thought it was going to be when we started,” said Stevenson during the March meeting of the HBPW Board.

The project went right down to the wire to complete the necessary tests in order to receive capacity credit this year from the Midcontinent Independent System Operator (MISO), which is a government agency that regulates the electric grid in this part of the country.

Capacity, among other things, represents a community’s potential energy reserves. Hannibal has needed to secure both sources of energy and capacity since June 1, 2017, when it began a self-managed energy plan.

According to Heath Hall, director of operations for the HBPW, initially only five of the generators tested near full load. The remaining generators had control issues. After a controls expert was called in, all 10 generators tested within their expected range.

“These 10 generators represent about 18.3 MWh in capacity credit for Hannibal,” said Hall. “We own this capacity and therefore do not have to purchase it on the open market each year at market prices. The open market prices can be volatile and we have no control over them. By owning this portion of our capacity requirements ourselves we know our cost and can budget accordingly. Also the cost stays very flat over a long period of time.”

The 18.3 MW of capacity represent approximately one-third of the city’s capacity requirement, which is roughly 60 MW.

In addition to the capacity credit the diesel generators provide the city there are other benefits, according to Hall.

“They can also be used for peak shaving. Peak shaving can occur if our customers are using more (power) than we estimated and registered with MISO. This can save us penalties for going over our registered peak,” he said. “The generators can also save us money if the price of power on the day-ahead market becomes higher than the price it takes to run the generators. If the cost on the day-ahead market rises above our price of fuel and labor to run the generators then we can run the generators and save some dollars for this portion of our power requirements. Customers won’t immediately see this on their monthly bills, but over the long term it should allow us to keep rates more stable.”

A few of the generators represent an insurance policy of the sorts.

“Two of the generators will be used for emergency standby units for the water treatment plant, river pump house and wastewater treatment plant,” said Hall. “Prior to these installations we had one undersized generator at the water treatment plant. We do not have one at the river pump house and did not have one at the wastewater treatment plant. During power outages these units will provide more than enough electricity to run these vital facilities and customers will not have any disruption or reduction in these services. During the spring 2013 straight-line windstorm we were very close to having sewer overflows and basement backups due to the wastewater treatment plant being out of power.”

In addition to having a generator at both the water treatment plant and wastewater treatment plant, the remaining eight generators are located at the Oakwood substation at Warren Barrett Drive and Orchard Avenue.

According to Hall, there is a misconception regarding how often the generators will be utilized.

“I have been asked by several customers if we are going to run the generators on a daily basis,” he said. “The day electric market is much cheaper today and most of the time historically than the cost of fuel and labor to run the generators. We will not be running them each day to provide electricity to our customers. It is just not cost-effective. We will, however, run them periodically to exercise the units and test their capabilities. We have invested a lot of time and money into the project. Having the generators available to run at a moment’s notice is part of our expectations and obligation to MISO moving forward. Exercising the units and performing other maintenance activities on them is a must to ensure they are ready to run.”

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