United Airlines flew the first U.S. commercial passengers Monday on a Boeing 737-824 powered partly with Honeywell biofuel made from algae, a Honeywell subsidiary announced.

Flight 1403, scheduled to arrive in Chicago's O'Hare airport at 1 p.m. CST from Houston, used a blend of petroleum-based jet fuel and aviation biofuel made from algal-oil, provided by Solazyme, according to Honeywell's UOP.

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"What we have is an evolving product," Jim Rekoske, the company's vice president and general manager for renewable energy and chemicals, says in an interview. "This is kind of a boutique fuel" now that costs about four times that of regular jet fuel, he says, because it's not yet widely available. He expects that will change as companies secure funding to build plants to produce it on a massive scale.

On Wednesday, Alaska Airlines plans two biofuel-powered passenger flights from Seattle, Wash., one bound for Washington, D.C., and the other for Portland, Ore., it announced Monday.

Honeywell's UOP developed the process for converting inedible natural oils and wastes into jet fuel that meets or exceed flight specifications and requires no changes to the aircraft or engine.

Rekoske said its Green Jet Fuel also offers as much as an 85% net reduction in greenhouse gas emissions compared to petroleum-based jet fuel. He said the company received Defense Department funding from 2006 to 2008 for its initial research to develop military-grade jet fuel from organic waste.

In August, President Obama announced a biofuels initiative and called on the Department of Energy, the Department of Agriculture and the Navy to each put in $170 million of existing funds to build plants that can make this fuel for the Navy. Rekoske said he expects companies will soon submit proposals for that federal funding

Honeywell's Green Jet Fuel has powered 24 commercial and military biofuel test flights so far, including a transatlantic flight on a Honeywell-operated G 450 business aircraft and a supersonic one on a Navy F/A-18 Hornet.

Rekoske said today's flight was the first commercial U.S. one carrying passengers, whom he says United notified in advance about the unique but approved fuel.