Congress has moved a step closer to implementing its vision of a more cost-effective and environmentally friendly way of heating the Capitol campus.

The Environmental Protection Agency announced Wednesday it would be allowing public comment until Oct. 1 on a proposed permit to allow the Architect of the Capitol to use “cogeneration” to generate heat and electricity simultaneously at the Capitol Power Plant and move toward greater use of natural gas.

If no objections are raised by that time, the EPA could immediately issue the permit.

“We appreciate EPA’s assistance in moving our permit request forward and to a successful outcome,” AOC spokeswoman Eva Malecki said.

Democratic leaders announced with much fanfare in 2009 that the plant would convert from using coal as its primary fuel to natural gas. The EPA permit would hasten that conversion, as coal is still one component of the plant’s fuel sources.

For more than a year, the AOC has been readying the Capitol Power Plant for cogeneration, which will employ a natural gas-powered combustion turbine to produce enough electricity to power the plant itself. The steam created through that process, meanwhile, would help heat the Capitol complex.

Cogeneration would reduce the Capitol’s reliance on boilers, AOC Stephen Ayers said in March 2011, and reduce energy consumption and emissions.

The project necessitated a $2 million commitment from Congress, included in the fiscal 2012 omnibus spending deal passed at the end of last year.

The remaining funding necessary to complete the project, Malecki said, will be made possible through a Utility Energy Services Contract, which allows government agencies to implement energy-efficiency projects at minimal cost as money is, over time, repaid with savings made possible by the new technology.

In March, the AOC submitted an application to the EPA for a “Plantwide Applicability Limit” permit, which would cap emissions at a certain threshold but allow the Capitol Power Plant some flexibility in how it chooses to generate power and heat through cogeneration — in this case, via two natural-gas fired cogeneration units that will be installed onsite.

The EPA permit, assuming it’s issued in October, wouldn’t be the final greenlight before implementation of the cogeneration technology can begin, however: The AOC will also need permits from the District government to ensure emission levels and construction plans meet local laws and standards.

Malecki said the expectation is to have the operation up and running “in the near future.” When that time comes, it will be the first time since 1951 that the Capitol campus has supplied its own electrical energy production. That function was eliminated from the Capitol Power Plant’s roster of activities as it was asked to provide steam and chilled water to more and more legislative branch facilities.

The Capitol Power Plant has been in operation since 1910 and provides heat and chilled water to 23 facilities on Capitol Hill.