SEMCO ENERGY GAS COMPANY SELECTS DTE ENERGY TO FUEL ITS HEADQUARTERS WITHCLEANENERGY July 7, 2020

SEMCO ENERGY Gas Company (SEMCO) today announced an agreement with DTE Energythatwill support SEMCO’s goals to lower operational carbon emissionsand take another critical step toward reducing its overall carbon footprint. Under the terms of thepartnership,SEMCO will purchase half of theelectricity supplied to its headquartersin Port Huron from renewable sources provided by DTE,beginning in July of this year.This move will offset 707 metric tonsof CO2e annually –the greenhouse gas emissions equivalent of an average passenger vehicledriving 1,754,442 miles*.The contract is made possible through DTE’s MIGreenPower program, a voluntary renewable energy program that allows customersto participate in DTE’s wind and solar projects by matching a portion of their energy use to Michigan-made renewable energy.SEMCO is one of the first commercial customers to enroll in MIGreenPower Wind, a new program under the MIGreenPowersuite of voluntary clean energy programs. MIGreenPower Wind is sourced solely from DTE’s wind portfolio andis the most affordable clean energy program the company offers. DTE will source the energy for this contract from Pinnebog Wind Park, located in Huron County. “Protecting the environment and minimizing ourimpact is one of SEMCO’s core values –partnering with DTE Energy underscores our commitment to serve as an environmental steward

2as we invest in sustainablepractices for our own facilities and operations,” said Colleen Starring, presidentSEMCO.SEMCOworked closely with DTE to identify cost savings measures to make enrolling in DTE’s MIGreenPower a nearly cost neutral endeavor. “MIGreenPower Wind is the first of several new MIGreenPower programs we plan on introducing over the next couple ofyears to meet our customers’ growing appetite for cleaner energy,” said Brian Calka, director, DTE Energy. “Growing MIGreenPower participation fuels the development of renewable energy in Michigan, and we’re glad to partner with SEMCO to help deliver on their sustainability goals.”SEMCOis dedicated to identifying additional opportunities across its operations in Michigan to further lower greenhouse gas emissions and reduce environmental impact.SEMCO ENERGY Gas Company, a division of SEMCO Energy, Inc., and a wholly-owned subsidiary of AltaGas, Inc.,is headquartered in Port Huron, Michigan. SEMCOis a regulated public utility that delivers natural gas to approximately 300,000 residential, commercial and industrial customers in Michigan. Service territories include portions of the southern half of the state’s Lower Peninsula (including in and around the cities of Albion, Battle Creek, Holland, Niles, Port Huron and Three Rivers) and in the central, eastern and western parts of the state’s Upper Peninsula.*According to the EPA Greenhouse Gas EquivalenciesCalculator