Indiana's Mammoth Solar hits 900 MW, nearing its 1.3-GW finish line | Clean Energy Briefing — October 9, 2026

TODAY'S LEAD: Doral Renewables is bringing the bulk of what will be one of the largest operational solar projects in the country online in Pulaski County, while a new Wood Mackenzie analysis finds four-hour battery storage now beats gas peakers on cost across North American markets.

KEY DEVELOPMENTS

Mammoth Solar Brings 900 MW Online in Indiana: Doral Renewables' massive 1.3-GW solar complex in Pulaski County is activating 900 MW across three phases, putting it among the largest operational solar installations in the U.S. (Solar Power World). Read More: Solar Power World.
ContourGlobal Starts Building 509 MW Arizona Hybrid: Project Sterling in Mohave County pairs solar generation with 1.4 GWh of battery storage; Tesla has signed a power purchase agreement for the facility (Solar Power World). Read More: Solar Power World.
Maryland Storage Procurement Falls 360 MW Short: The state's first bulk storage solicitation awarded only 440 MW of its 800 MW target after two project withdrawals, landing contracts with Flatiron Energy's 400 MW Chalk Point and REV Renewables' 40 MW Jade Meadow III (PV Magazine USA). Read More: PV Magazine USA.
Wood Mackenzie: 4-Hour Batteries Beat Gas Peakers Everywhere: A global LCOE analysis covering 43 markets finds four-hour battery storage now costs less to install than open-cycle gas turbines, with data center demand accelerating long-term storage investment (Utility Dive). Read More: Utility Dive.
Stardust Power Opens Houston Hub for $1.2B Lithium Refinery: The battery chemical manufacturer established a project execution office in Houston to support its lithium refinery under construction in Muskogee, Oklahoma, which broke ground in early 2025 (Solar Builder). Read More: Solar Builder.

Solar & Storage

The sheer scale of utility-scale solar under construction or coming online this week is hard to ignore. In Indiana, Doral Renewables is bringing 900 MW online at its Mammoth Solar complex in Pulaski County — three phases of a project that will total 1.3 GW when fully complete. At that capacity, Mammoth cements its position as one of the biggest operational solar plants in the country. For Midwestern grid planners wrestling with coal retirements and rising industrial load, a gigawatt-class solar asset in northern Indiana is no longer hypothetical. Read More: bringing 900 MW online.

Out in Arizona, ContourGlobal has broken ground on Project Sterling in Mohave County, a solar-plus-storage hybrid pairing up to 509 MW of solar generation with 1.4 GWh of battery storage. Two outlets covered the groundbreaking with slightly different capacity figures — Solar Power World reported 509 MW solar and 1.4 GWh storage, while PV Tech described the facility at 420 MW — but the core facts are consistent: this is a major Southwest hybrid plant with Tesla locked in as an offtaker through a power purchase agreement, and completion is expected by 2028. The project was first flagged in yesterday's briefing; what's new is the confirmed Tesla PPA, which gives the facility a creditworthy buyer before a single panel is installed. Read More: Solar Power World, PV Tech.

Not every solar project is moving forward smoothly. In Ottawa County, RWE's Silver Maple Solar project is heading to a bench trial over land access disputes with local property owners. The conflict affects roughly 30% of the proposed development area, and the outcome could determine whether the project proceeds at all. Developers watching this case should note how land-access litigation — distinct from the more common zoning and permitting fights — can threaten a project's footprint late in development. Read More: heading to a bench trial.

Community friction is surfacing elsewhere too. In New Mexico, East Mountain residents near Sandia Park plan to discuss the Diamond Tail Solar Project and Campbell Ranch development at an October 19 community gathering. And straddling the Wyoming-Colorado border, the Chalk Bluffs Energy Project — which combines wind, solar, and battery storage with a 16-mile transmission line connecting to Colorado substations — faces pushback from Laramie County residents concerned about visual and property-value impacts. These local opposition stories share a pattern: even in regions with strong renewable resources, the transmission and land-use footprint of clean energy projects remains the hardest sell. Read More: discuss the Diamond Tail Solar Project, pushback from Laramie County residents.

Policy & Markets

The most consequential data point of the day comes from Wood Mackenzie, whose new global LCOE analysis finds that four-hour battery storage systems are now cheaper to install than open-cycle gas turbines across all 43 markets studied, including North America. The firm points to data center load growth as a key driver of long-term storage and renewables investment, while gas turbine supply backlogs and fuel price volatility are pushing peaking costs higher. For utility procurement teams still debating gas versus batteries for peaking capacity, Wood Mackenzie's numbers leave little ambiguity — the economics have flipped. Read More: four-hour battery storage systems are now cheaper to install than open-cycle gas turbines.

That finding lands at an awkward moment for Maryland, where the state's inaugural bulk storage procurement just came up 360 MW short of its 800 MW target. The Public Service Commission awarded contracts for two four-hour systems: Flatiron Energy's 400 MW Chalk Point project and REV Renewables' 40 MW Jade Meadow III. Two other projects withdrew, and one was passed over. The shortfall matters because Maryland's Next Generation Energy Act set the 800 MW target as a grid reliability benchmark; hitting barely half suggests the state may need to sweeten terms or accelerate subsequent procurement rounds to stay on schedule. Read More: came up 360 MW short.

On the supply chain front, Stardust Power opened a project execution office in Houston to manage its $1.2 billion lithium refinery under construction in Muskogee, Oklahoma. The refinery, which broke ground in early 2025, aims to produce battery-grade lithium for energy storage and electric vehicles, positioning itself as one of the largest domestic lithium refineries. With battery storage now cost-competitive against gas peakers by Wood Mackenzie's reckoning, domestic lithium refining capacity becomes a bottleneck worth watching — every gigawatt-hour of new storage needs feedstock. Read More: opened a project execution office in Houston.

In Iowa, the Utilities Commission denied Summit Carbon Solutions' request to consolidate regulatory dockets for its carbon sequestration pipeline, which connects laterals to multiple biorefineries as part of a phase 2 expansion. The procedural setback means Summit will have to navigate each docket separately — adding time and complexity to a project that has already faced years of landowner and regulatory resistance across multiple Midwestern states. Read More: denied Summit Carbon Solutions' request.

LOOKING AHEAD

New Mexico Community Forum on October 19: East Mountain residents will gather in Sandia Park to discuss the Diamond Tail Solar Project and Campbell Ranch development — an early test of local sentiment before any formal permitting decisions.
Silver Maple Solar Trial in Ottawa County: The bench trial over land access for RWE's solar project could set a precedent for how developers handle property disputes affecting a significant share of a project's footprint.
Maryland's Next Storage Move: After falling 360 MW short in its first procurement, the PSC will face pressure to launch a second round or adjust contract terms to attract enough projects to meet the 800 MW legislative target.

TODAY'S QUICK ANSWERS

Q: What does Wood Mackenzie's peaker cost analysis mean for utilities still planning new gas turbines?

A: It removes the last major economic argument for open-cycle gas peakers. With four-hour battery storage now cheaper across all 43 markets Wood Mackenzie studied — and gas turbine backlogs lengthening delivery timelines — utilities filing for new gas peaking capacity will face increasingly difficult justifications before regulators and investors. Data center load growth is only widening the gap by pulling more capital into storage.

Q: Why should developers care about the Silver Maple Solar land access trial?

A: Because the dispute affects 30% of the project area, and the outcome could determine whether a partially assembled land position is viable or fatally compromised. If the court rules against RWE, it signals that developers cannot rely on contested easements or access agreements to build utility-scale projects — raising due diligence costs industry-wide.

Q: What does Maryland's storage shortfall signal for other states launching first-time procurements?

A: That setting an ambitious megawatt target is not enough. Maryland's 800 MW goal attracted interest but lost projects to withdrawals, netting only 440 MW. States designing similar programs should build in contingency mechanisms — larger initial solicitation pools, backup bidder lists, or penalty provisions for late withdrawals — to avoid falling short on round one.

THE BOTTOM LINE: Battery storage has crossed the cost threshold against gas peakers in every major market, yet Maryland's procurement shortfall shows that economic competitiveness alone won't fill the pipeline — state programs need deal structures that actually keep projects from walking away.