CHICAGO (WHTM) — Ten global companies will work with United Airlines – the fourth busiest airline at Harrisburg International, according to airport statistics – to support a switch to cleaner fuels, the Chicago-based airline announced Tuesday.

Airline officials said the other companies would join United by lobbying politicians for policies that support green energy and by covering the cost differential between petroleum-based jet fuel, which makes up most of the current commercial jet fuel supply chain, and sustainable aviation fuel, or SAF.

United’s top executive drew a distinction between the new effort and longstanding carbon offset programs, whereby companies try to mitigate their impact on climate change by paying for climate-friendly projects – reforestation, for example. Some environmentalists have said the benefits of those programs are overstated.

“While we know that aircraft are never going to be completely decarbonized, we are not going to use offsets as the way to get to 100 percent green and instead are going to focus on carbon sequestration,” Scott Kirby, United’s chief executive officer, told media in a call discussing the new program.

SAF costs two to four times as much as traditional jet fuel, said Lauren Riley, United’s managing director of global environmental affairs and sustainability, speaking on the same call.

The companies participating are Nike of Beaverton, Ore.; HP of Palo Alto, Calif.; Boston Consulting Group; Palantir, a Denver-based software company; Deloitte, a British consulting firm with its U.S. headquarters in New York City; the European companies CEVA, DHL, DSV and Siemens; and Takeda Pharmaceuticals of Japan.

The airline said individual consumers can participate too by contributing to SAF research projects or contacting their elected officials through an automated system available on its website.

United will continue offering voluntary carbon offsets to consumers on its website – in other words, allowing them to contribute a sum of money that ostensibly makes up for the environmental impact of their flights – although “I expect that won’t last forever,” Kirby said, again aligning himself with environmentalists and distancing himself from some other airlines (including United itself in the past), which have touted their carbon offset programs.

Is it more than just “marketing” and “talk,” as Kirby said?

The airline is genuinely “taking a swing” at climate change, said Brett Snyder, founder and author of the airline industry blog Cranky Flier.

“They really seem to have a strong focus and interest in investing in this instead of just saying, ‘We’re going to have a carbon offset,’” Snyder said, naming other United announcements, including investments in carbon sequestration and electric aircraft. And “they’ve got some good corporate partners” in the new program, he said.

On the other hand, “until you actually see it in action and working and reducing the impact, it’s all just theoretical,” Snyder cautioned. “There are always grand plans, and that’s the easy part.”

Mark Jacobson, director of the atmosphere and energy program at Stanford University and a proponent of solar and wind energy, was even more skeptical. Jacobson said even fuels considered sustainable have many of the name negative impacts as traditional fuels, including “black carbon,” the main component in soot.

“All they’re doing is continuing to kill people with their pollution and continuing to kill people with global warming,” Jacobson said. “What they really need to do is go to electricity and hydrogen fuel cells for all their aircraft. They’re not the aircraft builder, but they can encourage it.” Jacobson said the 290 companies in the “RE100,” which doesn’t appear to include any airlines, have committed to true sustainability. Asked whether that’s simply more difficult for an airline than for other companies, Jacobson questioned whether airlines like United are even doing what’s technologically feasible today.

“Are they buying solar farms? Are they buying wind farms?” he asked. “They should be purchasing renewables, battery storage – electrify all their ground transport vehicles.”

United is the third or fourth largest U.S. airline overall, depending on the measure used, according to an abc27 analysis of Cirium schedule data, behind Fort Worth-based American, Atlanta-based Delta and in some cases Dallas-based Southwest.