The groups filed a lawsuit last year to gain access to emails between a House Republican lawmaker and utility companies.
Best estimates from the state indicate Indiana’s water utilities need around $15 billion to improve their infrastructure.
A recent report shows the plant’s capacity factor – the amount of coal the plant is gasifying – was just more than 10 percent for the month of April.
Utilities are allowed to increase rates to make up for the revenue they lose to energy efficiency programs.
Duke Energy is seeking to recover construction costs for the Edwardsport coal gasification plant in hearings that begin Wednesday.
The report says Indiana’s energy efficiency programs provide a benefit to the state, and will continue to do so in the next several years.
The Indiana Utility Regulatory Commission recently allowed Duke Energy to pass the costs of building its Edwardsport plant on to its customers.
Duke Energy's $1.9 billion proposal would modernize its electricity grid across the state.
Duke Energy is seeking proposals from companies that want to supply it with solar energy in order to fulfill a legal settlement Duke made last year.
Duke is now requesting approval of an additional $500 million, promping the Office of Utility Consumer Counselor to recommend a cap on total costs.