As a community we want to make wise decisions about our infrastructure and our future. Wise decisions require consideration of facts, needs, and consequences. On January 19 of this year, the City Council voted to “pause” the building of an electric transmission line and substation that had been approved by voters in 2015 and for which bonds had been issued. The Council has not announced when it will again review this “pause” nor has it talked much about how the pause is affecting economic development or our electric service. City staff, however, recently announced that it is preparing a request to extend the moratorium on building downtown due to concerns with electric infrastructure.
We asked Connie Kaprowicz of Columbia Water & Light, who joined us in the August on-line Trib Talks forum, to help us understand some of the issues involved.
1C1C: When we look at past forums, new articles, and on-line comments, we seem to be talking about two things, the Mill Creek substation and the overall transmission line. Can you explain why each is needed and how these inter-relate?
W& L: Electricity is generated at a power station or power plant from fossil fuels or renewable resources. Approximately 90% of Columbia’s energy comes from sources outside the city. Once the power is generated, it has to be moved to where it is going to be used. Large amounts of power are transferred with electric transmission lines. An interconnected network of transmission lines is commonly referred to as the power grid.
Transmission lines feed into substations. At substations, transformers step down the power to lower voltages. From there, power is delivered to individual electric customers by distribution lines.In the older sections of town, distribution lines are mounted on wooden poles. New distribution lines in Columbia must be placed underground according to city ordinances.
1C1C: Does the Mill Creek Substation still need to be built even if the transmission line is built on a route other than Option A?
W & L: Yes, As noted above, the Mill Creek substation is needed due to the electric load growth in the southern area of town. Our other substations serving the area are loaded over the suggested amount. As we explained at our May work session presentation, electric systems must have reserved capacity for times of high loads and/or problems with the system such as those caused by storms. Both the Hinkson and Perche substations are overcapacity as shown in the chart below.
- Substation loading goal: two transformers at 50%, three transformers at 66.6%
|Year||Grindstone (3*)||Hinkson (3*)||Perche (2*)|
*number of transformers
1C1C: Suggestions were made in past forums and in Trib Talk that rather than building the Mill Creek substation, additions could just be made at another substation like Hinkson. You indicated in our August on-line forum that that was not a good option. Could you explain in layman terms why?
W & L: There is not room to expand the Hinkson Creek substation. Even if the University would sell us additional land, it is not the best site since it is prone to flooding. Even then we would still need to build transmission lines to get the power to where it is being used. That would involve running lines through the south side of town.
We have also already purchased the land for the Mill Creek substation which is in a better spot geographically to serve the southern side of town.
1C1C: You indicated in the August on-line forum that even if we went with the suggested alternate route for the transmission line, which has been dubbed “Option E”, additional transmission lines would still be needed on the south side of town. Can you say more about that?
W & L: Option A resolved two technical issues: One is providing a second feed into the Perche Creek substation and the other is to reduce substation loading (see info above). Option E, which was proposed by the Mayor at a council work session in May, 2016, addresses the issue of getting a second 161 kV feed to Perche substation. It does not address the need to reduce substation loading. There was no direction from the City Council on how they would like to tie the Mill Creek substation into the transmission and distribution system in the event that the transmission line route changed. So that issue would still need to be resolved.
1C1C: One of the ideas about Option E was that we might be able to place our lines on poles owned by Ameren UE and Associated Electric. What is the status there?
W & L: After the Mayor proposed Option E we first needed to do some modeling work. Modeling work evaluates any possible engineering problems that could impact the entire system so it is very time consuming. Think of it as looking at all the things that can happen during one minute of play during a team sport. There are many different possibilities and combinations of things that could present risk. After our modeling did not find any red flags, we sent our modeling work to our neighboring utilities to analyze and get back to us. We do not have a response yet from any of them. Once we do hear back from them, we could possibly do another work session with council to see if they want us to pursue Option E. We still need feedback on what to do about the Mill Creek substation.
1C1C: During our August forum at least one citizen suggested that we need not be concerned about delay in moving forward with these projects because the electric system didn’t shut down over the summer. Can you comment on that?
W & L: In our personal lives, living without electricity is hard. For businesses, it can impact their income and level of service to their customers. During the storm in 2014, the wooden 80’ tall transmission poles on Fairview snapped and it took some of the largest line trucks in the Midwest to repair them. The outage from this storm lasted for five days for some of the customers. Every situation is different when it comes to problems. Small transformers on distribution lines can be easily replaced. Damage or equipment failure at the substations could take weeks/months. That is why we plan for redundancy and reserves.
Think of a road system. When there is construction or an accident you have to detour. The electric transmission and distribution system should never be run at 100% because space is needed if we need to isolate a problem and serve customers from another line. Unlike traffic, electricity can’t get stuck in a traffic jam because overloading (heavy traffic) could cause cascading problems. This would be like what happened on the east coast in the early 2000s.
Reserves refers to having extra energy available to serve an unexpected peak. This is federally regulated as well. We have to show what our peak usage is and then secure extra energy resources beyond that. All of this a part of keeping the electric grid reliable.This summer we were close to a new electric peak but luckily it rained and a cold front moved in.
Transmission planning is complex and takes time. We first identified the need for this project in 2004 when our models indicated we would have issues with the system even under normal conditions by 2020, taking into account growth. At present, we could experience problems even before 2020, particularly if any element of the system is out of service (weather, malfunctioning equipment, etc). I personally do a lot of worrying during every storm and during periods of hot, humid weather when it doesn’t cool down much at night.
1C1C: In an earlier chat you mentioned that the Average Electric Service Availability Index is 99.9876 for Columbia out of a hundred and that a drop in this could hurt our economic development efforts. Please expand on this.
W & L: Our community has invested in our electric system since 1904 so it is reliable. Having a reputation of unreliable electric service is not a good thing when we seek new businesses in our community. Reliability is affected by a number of factors related production, demand from customers, and delivery. Many people don’t realize that unlike water or natural gas, electricity can’t be stored by utilities in large amounts (existing batteries for use with solar energy production are very expensive and can only store a small amount) . Electricity also does not run in one direction through a “pipe” like water or natural gas. Electrons move in different ways which is one of the things that makes electrical engineering a specialized and complex field. Businesses – particularly those that are energy intensive or, like medical facilities, that rely on equipment that is sensitive to fluctuations in power, – are concerned about both power quality (avoiding fluctuations in voltage) and availability on demand.
1C1C: Can you say more about “availability on demand”?
W & L: Because electricity can’t be stored, an electric utility has to provide the power needed at every minute of the day, even as the level of demand varies. Although the amount of electricity that the city needs over time is measured in kilowatt hours the level needed at any given time is referred to as “demand”. If everyone in Columbia, especially commercial customers with large equipment, turned on everything all at once for 2 minutes, we would have to meet that huge demand for those 2 minutes. Meeting that demand is not just a matter of producing the electricity – we have to deliver it as well. This means that our transmission and distribution systems must be robust enough to meet any spikes in demand at any given moment in time. Our ability to deliver is affected by both transmission and distribution constraints. In an ideal world, demand would be constant throughout every minute of the day. We don’t live in an ideal world, and that is why we have to build a system that can handle spikes in demand. Since large commercial customers and industrial customers demand can have a big impact on our system, they are charged a kilowatt hour charge (like residential) but they also have a separate demand charge. The following graphic will help you understand energy v.demand for our system.
1C1C: Thank you Connie. To our readers, continue to check this blog for more posts in this series!