A key renewable energy component that was intended to set apart the state’s largest development project from run-of-the-mill suburbia is becoming iffy, city and county officials have learned.

Officials conceded last year that the possible use of geothermal energy at the redeveloped former Twin Cities Army Ammunition Plant (TCAAP) site, long touted by Ramsey County and Arden Hills, may not happen.

Now it emerges that prospects are clouded for a 40-acre solar panel array that was supposed to help power the 427-acre megaproject, called Rice Creek Commons.

Ramsey County hasn’t given up on the idea. But what the commissioners learned of its status led to questions about what alternative uses might be made of the land set aside for solar.

“We haven’t thought in those terms yet,” county planner Josh Olson told a joint city-county commission overseeing the project.

“We want to continue to explore the solar installation and our conversations with Xcel Energy have been positive,” he added.

But with the recent change in administrations in Washington, D.C., he said Xcel needs to be certain that a solar array would pencil out financially and not rebound in a negative way on rate payers. Tax credits for solar are an issue.

Meanwhile, the prospects for a Minnesota Department of Public Safety operations center on the edge of the TCAAP site suffered a blow when the Legislature declined again this year, as it has before, to include that project in its bonding bill.

The city and county have a master developer with plans to fill the site with an innovative blending of single-family neighborhoods and a high-density town center area with shopping and offices, all laced together with trails and natural areas.

But nagging issues connected to age-old pollution on the site have pushed back the start date for private-sector work on the site from this construction season to next, assuming a satisfactory master development agreement can be forged.

In the meantime, public sector work to create something special at the site is moving ahead, Olson said.

The re-meandering of Rice Creek as a key natural amenity — indeed, the signature feature after which the development has been tentatively named — was completed last year.

Now a pedestrian bridge over the creek has been installed, and the county parks department is at work on planning processes for county-level parks improvements tied to the site, Olson said. A public engagement process has been launched to make sure citizens have a voice in that.

“This planning process will review possible parks development and recreational opportunities,” Olson said.

The last master plan came in 2013, before the most recent planning for the site, he said, and the county wants to study “how to better interface with Rice Creek Commons.”

Arden Hills Mayor David Grant said he has seen the new bridge and likes the looks of it. But county commissioners were uneasy about the potential loss of solar power and pressed Olson on that.

“This [solar] project can still happen,” Olson said, “but because so much solar is coming online, Xcel is close to hitting what they are mandated to do in that area. A lot of our conversations now center on other goals for energy integration.”