The sources of energy reported by IMEA are listed below in pie-chart format. Prairie State and Trimble County are the jointly owned coal-fired generation resources that have totaled roughly 70-80% of the energy from IMEA.
Since Naperville purchases all its power supply requirements from IMEA, the Naperville and IMEA sources of electricity are one and the same, except for the difference from local solar. And local solar installations represent only 1% of Naperville’s electricity.1
IMEA Fiscal Year 2026 (May 1, 2025 thru Apr 30, 2026)
The following information was received from IMEA:
Additionally, we requested and received the following generation amounts used to calculate the above pie-chart percentages:
- Prairie State – 1,855,840,880 MWh
- Hydro – 18,362,578 MWh
- Wind – 321,689,926 MWh
- Solar – 59,192,838 MWh
- Trimble County – 853,101,000 MWh
- Member Generation – 9,589,804 MWh
- Short-term Market Purchases – 696,728,282 MWh
- Total Energy – 3,814,505,308 MWh
IMEA Fiscal Year 2025 (May 1, 2024 thru Apr 30, 2025)
The following information was received from IMEA and shared by the Naperville Electric Utility:
NOTE: The reported percentages of coal-fired generation for Prairie State and Trimble County for IMEA Fiscal Year 2025 are lower than the prior IMEA Fiscal Year 2024, apparently due to planned and unplanned outages at both plants. And the percentage of Market Purchases apparently increased, as a result of the lost coal-fired output. Prairie State net generation was 9.9% lower and Trimble County net generation was 8.7% lower, compared to the prior IMEA Fiscal Year 2024 For further generation and outage details, see our webpages Prairie State Generation and Trimble County Generation.
IMEA Fiscal Year 2024 (May 1, 2023 thru Apr 30, 2024)
The following information was received from IMEA and shared by the Naperville Electric Utility:
IMEA Fiscal Year 2023 (May 1, 2022 thru Apr 30, 2023)
The following information was received from IMEA and shared by the Naperville Electric Utility:
IMEA Fiscal Year 2022 (May 1, 2021 thru Apr 30, 2022)
Unlike previous years, IMEA did not report sources of electricity in the IMEA 2022 Annual Report. The following information was received from the Naperville Electric Utility:
IMEA Fiscal Year 2022 Energy Production By Source
IMEA Fiscal Year 2021 (May 1, 2020 thru Apr 30, 2021)
IMEA provided the following in the IMEA 2021 Annual Report:
IMEA Fiscal Year 2020 (May 1, 2019 thru Apr 30, 2020)
IMEA provided the following in the IMEA 2020 Annual Report:
IMEA Fiscal Year 2019 (May 1, 2018 thru Apr 30, 2019)
IMEA provided the following in the IMEA 2019 Annual Report:
IMEA Fiscal Year 2018 (May 1, 2017 thru Apr 30, 2018)
IMEA provided the following in the IMEA 2018 Annual Report:
Notes:
1 Annual generation of electricity from Naperville solar installations is roughly 1% of Naperville’s total purchases from IMEA. As of April 30, 2024, Naperville reported 20 commercial and 913 residential solar installations for a total installed solar capacity of 9,708.68 KW. Using a generous estimate of an 18% average capacity factor, that total installed solar capacity can be calculated to have produced 15,308,647 kWh. That would represent 1.2% of Naperville’s total calendar year 2023 purchases from IMEA of 1,251,510,681 kWh.