* $218 million

Minnkota Power Cooperative, Center

This Grand Forks-based cooperative will invest more money over the next three years to clean up pollution from its Milton R. Young units at Center than any investment since original construction.

The co-op's environmental manager, John Graves, said Minnkota will spend $218 million on equipment to remove sulfur dioxide from the plant's emissions to comply with new federal air quality standards.

"This is the largest project done at the plant in some time," Graves said. "I can't think of anything close to that dollar amount since the plant was built."

The work will require a peak of 400 workers and will overlap with a similar project at Basin Electric Power Cooperative's Leland Olds Station, about 20 miles up the road.

Graves said foundation work will start in late summer on a scrubber to Unit 1, the older of the two units at Center.

The unit went on line in 1970, before sulfur removal was required. Regulations to reduce "regional haze" will bring an end to the leeway for old coal-fired plants.

The new "wet" scrubber, which uses limestone slurry to bond with the SO2, should remove 95 percent of the sulfur from Unit 1, Graves said.

Now, with no scrubber, the unit exhausts 17,000 tons of sulfur gas every year.

Unit 1's new scrubber will get tied to the emission stack from its newer sister Unit II and be on line in May 2011.

Meantime, Unit II will get a new emission stack, new duct work and some internal changes, Graves said.

Workers will be at Minnkota to work on both units, installing equipment to reduce more than half the amount of nitrous oxide from plant emissions.

Graves said finding available workforce has been a concern. Plant operators try to stagger maintenance and projects to ensure there's enough labor to go around. Cooperation will be necessary with everyone facing the same regional haze deadline of 2013.

* $410 million

Leland Olds Station, Stanton

Basin Electric Power Cooperative is going "sky high" to reduce sulfur dioxide from its coal-fired plant at Stanton.

A new 600-foot emission stack is slowly rising on the plant's site alongside the Missouri River.

The new towering stack - as high as the stack at Basin's Antelope Valley Station near Beulah and more than two and a half times higher than the state Capitol building - will replace two aging emission stacks and eventually tie into new limestone scrubbing units to remove sulfur dioxide.

Work on the massive project started last summer. Basin's construction supervisor, Mark Nygard, said stack concrete construction is a little past mid-way. He said it should "hit the top" in mid-July as crews go on a round-the-clock concrete pour. The stack will encircle two fiberglass columns that will be tied into a scrubber on each of the plant's two units.

The column linings will be fabricated on site in sections and hoisted to the top of the 600-foot high stack. The new emissions stack also will require construction of internal platforms, an elevator, electrical wiring and emissions monitoring equipment.

There are about 100 workers at the plant site now and that number will peak at about 400 workers this winter.

The first scrubber for Unit 2 will go on line in 2009 and the second for Unit 1 in 2010.

The scrubber facilities, along with a reagent facility where limestone is pulverized and slurried with water, are also under construction. They will be massive components of the overall project without the impressive stature of the stack.

Nygard said finding enough workers hasn't been a problem so far, but that may change when labor demand hits its peak.

He said being a "little bit ahead of the curve" of similar projects in the area should help.

* $700 million

Great River Energy - Coal Creek Stations at Underwood, Stanton Station, Spiritwood Station in Jamestown

Great River Energy, headquartered in Maple Grove, Minn., is two years into a $130-million, seven-year project to replace the brick liner in the emission stack at Coal Creek with welded sections of nickel alloy.

The heightened stack will jut 683 feet high, just slightly under the profile of the IDS Tower in downtown Minneapolis, and improve the plant's ability to remove sulfur dioxide from its emission stream.

The most massive project for Great River in Coal Country involves construction of eight coal dryers - four integrated into each unit at Coal Creek -to remove about 25 percent of the water from lignite before it's burned in the boilers. The dried coal burns cleaner and hotter, with reduced emissions and more BTus.

The coal drying technology is unique to Great River, and several patents are pending. Great River will market the technology to other coal operators and, at this point, won't reveal what its own coal drying project will cost, except within the larger framework of the $700 million in total projects.

Great River also will spend $130 million to install a scrubber on its old Unit I at Stanton and upgrade the emission stack on Stanton's Unit II. This work is in the design phase and construction should start in 2010 to go on line in 2012.

The cooperative is spending $10 million to upgrade the control room at Coal Creek and plans another $20 million in a Great American Energy project to build a facility to sell dried coal to niche market users.

Outside Coal Country, in Jamestown, Great River is spending $276 million on a 99-megawatt coal plant integrated with an energy complex that includes Cargill's malting plant and potentially an ethanol plant. Spiritwood will take dried coal from the Great American Energy plant at Coal Creek, creating the longest in-state coal haul.

Spokesman Lyndon Anderson said the work is calling for hundreds of additional workers, a number that gets pushed as high as 1,000 during maintenance outages.

* $300 million

Basin Electric Power Cooperative - Antelope Valley Station at Beulah

Basin and Powerspan Corp. are moving forward on the engineering and design of a commercial-scale project to capture carbon dioxide from a unit at the Beulah plant.

Construction is expected to start next year and the technology will go on line in 2012.

The captured CO2, a greenhouse gas that is expected to be subject to federal regulation, will be blended with the carbon gas from Basin's adjacent synthetic fuels plant into a pipeline and delivered to oil fields for enhanced oil recovery.

The demonstration project would capture about 1 million tons of CO2 from a 120-megawatt slipstream from Unit 1 at AVS, making it among the largest carbon captures in the world.

* $2 billion

Florida Power and Light and Minnesota Power

The two companies recently announced plans to construct far and away the largest wind farm ever developed in North Dakota, encompassing a 250-square-mile area through southern Oliver and Morton counties.

The wind turbines would generate 1,000 megawatts of electricity for Minnesota Power. The company is gaining a transmission line into Minnesota at the same time it is losing access to coal-fired electricity from the Milton R. Young plant at Center.

The wind farm will require construction of 500 to 700 turbines, depending on their output and placement, and fill that transmission line with renewable energy from wind.