Understanding how electricity is stored and used is not only useful in a high school science class, but also helpful in understanding how Lane-Scott Electric determines our power requirements, the basics of electricity billing, and how you can better manage your energy use. As consumers of electricity, we expect to be able to flip a switch at any time and have power available to serve our multiple and simultaneous electrical needs. In order to understand how this power is available, you must first know the difference between consumption and demand.
Demand (represented in kilowatts or kW) is a measure of how much energy is consumed at a single point in time. In general, the more electrical devices used at one time, or larger equipment requiring more voltage, the more electricity is required at once, and the higher demand. Demand is generally measured in 15-minute intervals.
Consumption (represented in kilowatt-hours or kWh) is how much total electricity is used over a period of time.
Assume 10 lights, each using 100-watt bulbs, are turned on. This usage would consume 1,000 watts, or 1 kW of electricity. If lights are left on for 2 hours, that would consume 2 kilowatts per hour (kWh) of electricity.
Now, assume 5, 100-watt lights are used for 10 hours. The consumption is 500 watts, or 0.5 kW of electricity. However, because the 5 lights ran longer, 5 kWhs of electricity is used.
Why is demand important?
The faster Lane-Scott members are consuming energy, the more demand we must be able to supply. How much energy the system must be able to supply on demand to meet the instantaneous load is called its capacity. If there is not enough capacity… there’s not enough electricity. Have you ever tried to turn on a hair dryer while drying clothes on the same circuit and blown a fuse? The circuit did not have enough capacity to handle the electricity requirements of both. Lane-Scott works to ensure capacity meets the demand, so none of our members are deprived of their energy needs.
How does demand determine Lane-Scott’s power requirements?
Lane-Scott Electric, along with six other electric co-ops and one subsidiary, receives wholesale power from Sunflower Electric, through a complex mixture of electrical generation sources that travel thousands of miles of electrical lines. Our wholesale power is scheduled through the Southwest Power Pool (SPP). The SPP and Sunflower have to provide enough electric generating capacity to meet peak demand (the highest point of usage), generate enough electricity to meet annual usage on the entire grid, and operate the transmission system in a manner that will deliver electricity to each cooperative. Ultimately serving each cooperative members’ energy needs instantaneously.
How is demand paid for?
Lane-Scott pays a demand charge to Sunflower for the wholesale power it consumes as a total system. The demand charges are also calculated based on the highest demand during the month.
Both consumption and demand charges are part of every member’s bills. Smaller electricity users, such as residential meters pay one rate of charges for electricity service, covering both consumption of electricity and demand. This simple, combined charge is possible because there is little variation in electricity use from home to home.
This is not the case with commercial and industrial members, whose electricity use, both consumption and demand, vary greatly. Some need large amounts of electricity occasionally (such as large pump motors), others almost constantly such as manufacturing a product, or running a process that involves motors and electrical equipment.
How does demand affect electricity bills?
The demand charge will be a large part of the bill if the customer uses a lot of power over a short period of time, and a smaller part of the bill if it uses power at a more constant rate throughout the month. Remember, demand will only show as a separate charge for high usage meters such as large commercial, industrial, and irrigation pumps. Here are some sample rates to illustrate how demand affects an electric bill.
Demand = 10 kW x $12.00/kW = $120
Consumption = 20 kWh x $.08 = $1.60
Total = $121.60
Example 2: Running 2kW load for 10 hours:
Demand = 2kW x $12.00/kW = $24.00
Consumption = 20 kWh x $.08 = $1.60
Total = $25.60
As you can see, both examples use the same amount of energy (20 kwh), and the total amount of work done is the same. The difference between the bills is based entirely on the highest demand recorded during any given 15-minute period at that meter that month.
How can I save energy?
Every member can help! In general, there are two strategies for reducing demand.
Change when the equipment is on. Our entire electric grid is connected, and the strain and stress of high demand affects the capacity of the whole system. Think about a 110-degree day in July. Every home and business’s air conditioners are working overtime, irrigation pumps are running non-stop, and all at the same time. What do you think happens? Demand during that time skyrockets. Running other appliances at night (or at off-peak times), or not running irrigation pumps during the heat of the day will lessen demand (and evaporation).
Remember demand is calculated in 15-minute intervals. So slowly turning on electrical equipment rather than all at once can reduce demand. Think of the immediate draw of electricity in a shop building when lights the heater, welder, air compressor, and any other equipment are all turned on at once.
Change what equipment is on. Changing equipment and appliances by upgrading to higher efficiency models will assist in demand reduction. Technology of appliances has become more efficient. Tankless water heaters and hybrid high efficiency water heaters are an example of this. When shopping for new appliances, look for five-star energy rated appliances. While the initial cost might be higher, these appliances will save energy and money over time. Some states also provide tax rebates for energy efficient upgrades.