AUGUSTA — The state once again will seek bidders to provide natural gas to state facilities in central Maine.

The Bureau of General Services announced late Wednesday it is seeking bidders to provide natural gas distribution services to state-owned buildings in Augusta, Hallowell, Waterville and Vassalboro.

Two companies, Summit Natural Gas of Maine and Maine Natural Gas, are already at work installing pipelines to and within the city of Augusta. Summit also is installing pipelines throughout much of the rest of the Kennebec Valley.

Those two companies battled the last time the state sought bids for natural gas, a process that ended last year when the bid process used by the state was deemed flawed and the bids rejected. Maine Natural Gas, whose bid the state selected initially, sued after the bids were rejected. The lawsuit was dismissed in March.

Now the state will try, once again, to secure a deal to bring natural gas to heat state facilities.

In issuing the request, state officials said the state is seeking to lower the cost of energy for state buildings, many of which are heated with oil.

“The conversion of heating systems at state facilities to natural gas will lower energy costs paid by taxpayers,” Gov. Paul LePage said in a news release. “In addition to lowering the cost to taxpayers, the expansion of natural gas lines is part of our administration’s overall policy of bringing affordable energy resources to residents and businesses to grow Maine’s economy.”

The request for proposals, which did not appear to be posted on the Bureau of General Services’ purchases website Wednesday, identifies four “high use” buildings in the Augusta area that must be connected to natural gas pipeline service by Nov. 1, according to the news release.

A total of 30 properties are expected to be converted to natural gas.

State officials noted the request for proposals covers only the distribution of gas, while the purchase of the gas supply will take place through a separate process.