MENOKEN, N.D. (AP) — Some day, the passenger jets that soar 35,000 feet (10.6 kilometers) over Dan McLean’s North Dakota farm could be fueled by corn grown on his land and millions of other acres across the Midwest.

It’s a vision the U.S. airline industry embraces and agricultural groups see as a key to ensuring strong future sales of ethanol, a fuel that consumes more than one-third of the nation’s corn crop and offers a cleaner-burning alternative for the nation’s airlines.

But making that dream a reality hasn’t been easy, in part because even as farmers would benefit from a huge new market for corn, the plan relies on federal tax credits triggered by capturing carbon dioxide at refineries and then moving the gas hundreds of miles through pipelines that would snake across the Midwest, including beneath farmers’ fields.

Some of those farmers, along with environmentalist and property rights groups, have gone before regulatory authorities in several Midwest states to oppose the lines, and frequently they have succeeded in at least slowing the process. A key decision is expected soon in Iowa.

“This whole thing is private industry -- rich private industry -- getting tax money, strictly tax money to bury this stuff,” said McLean, who opposes a line that would cross his farmland east of Bismarck. “That tax money is coming out of everybody’s pocket, and they’re going to walk away from it, and we’re going to be left with a big poisonous pipe running across the country.”

Supporters have faced such criticism for years as they seek approval of pipelines and tax credits. The credits would mean profits for refineries and help make the cost of the new fuel competitive with traditional jet fuel. But opponents see the pipelines as an expensive and potentially dangerous effort that tramples on property rights and fails to reduce greenhouse gases.

Gaining approval of pipelines has proved arduous.

Several companies have dropped their pipeline plans in the face of opposition and delay. The leading remaining company is Summit Carbon Solutions, which is seeking to build a 2,000-mile (3,200-kilometer) pipeline system through five Midwestern states — North Dakota, South Dakota, Nebraska, Minnesota and Iowa — with carbon dioxide emissions ultimately buried underground in North Dakota.

North Dakota regulators last year denied a siting permit for Summit but later agreed to reconsider. South Dakota regulators in September rejected Summit’s application, but company officials said they would file again.

Summit must seek approval from individual counties in Nebraska, and one county earlier this year denied a permit. In Minnesota, regulators are doing an environmental review with future hearings planned.

An upcoming decision by the Iowa Utilities Board about whether to grant a pipeline permit and approve Summit’s eminent domain requests will be key to the larger effort throughout the Midwest. Iowa is the nation’s leader in corn and ethanol production.

To the renewable fuels industry, failure to gain approval of the pipelines could jeopardize a giant new aviation fuel market they believe would continue decades into the future, even as electric vehicles gradually replace gas-powered cars and traditional vehicles get more efficient.

“There’s a lot at stake here. We have a market that we can open up that can really underpin rural prosperity for the next two or three decades,” said Monte Shaw, executive director of the Iowa Renewable Fuels Association.

Essential to their efforts is a complicated formula that regulators established to approximate how much each ethanol plant contributes to global warming. Ethanol production already produces less carbon than gasoline production, but the industry must reduce that further to qualify for tax credits that require biofuel have a carbon score at least 50% lower than gasoline.

The Treasury Department recently tweaked that formula, taking into account the role farming practices, like planting cover crops and using no-till techniques, play in reducing carbon production. However, the rules require farmers to take all those steps so it will still likely be hard for ethanol to qualify without either carbon pipelines or a combination of several other expensive measures, like ensuring an ethanol plant is powered by renewable energy or biogas.

That’s why many in the biofuels industry argue that carbon capture pipelines are the best option to obtaining tax credits.

Without the sustainable aviation fuel market, Shaw and others contend corn prices could ultimately collapse in future years as demand from motorists wanes.

Currently, the roughly 200 U.S. ethanol plants have the capacity to produce 18 billion gallons of ethanol annually, though some are idle so the industry produces about 15 billion gallons a year, according to the U.S. Energy Information Administration. Passenger jets now burn about 25 billion gallons a year and that is expected to grow to 35 billion gallons annually by 2050.

And whereas most gasoline is now blended with 10% ethanol, sustainable aviation fuel would use a 50% blend of ethanol. It also requires about 1.7 gallons of ethanol for every gallon of jet fuel.

“We refer to carbon capture and sequestration as the key that unlocks the sustainable aviation fuel market,” Shaw said.

Ethanol trade groups estimate that federal tax credits for sustainable aviation fuel, combined with the existing credit for renewable fuels, can provide between $1.85 and $2.25 per gallon depending on the carbon intensity of the each ethanol plant. California, Minnesota and Illinois also have separate tax credits that can be added to the federal credits for fuel sold in those states.

With one of the biggest state tax credits of $1.50 in Minnesota or Illinois, some sustainable aviation fuel could receive nearly $4 per gallon in tax credits.

There is also a separate federal tax credit available for carbon sequestration but the rules won’t allow producers to claim it simultaneously with the main federal credit for sustainable aviation fuel, resulting in a smaller total tax credit.

The biggest ethanol trade groups — the Renewable Fuels Association and Growth Energy — say all tax credits combined would help make sustainable aviation fuel competitive with traditional jet fuel that has been selling for about $2.5 to $3 a gallon. And costs could drop if ethanol plants start producing the jet fuel on a large scale.

One small plant in Georgia is now producing 10 million gallons a year of sustainable aviation fuel from ethanol, but Geoff Cooper, president of the Renewable Fuels Association, said he expects the industry’s capacity to grow over the next five years to close to 800 million gallons annually.

Agricultural economists have estimated farmers would receive about $441 million more by 2050 if sustainable aviation fuel boosts ethanol demand from the current current 15 billion gallons to 28.5 billion gallons.