On January 7, a Continental 737 took a two-hour test flight from Houston, burning a 50-50 blend of petroleum-based jet fuel and an oil made from algae and a scrubby weed. Similar tests have been conducted in New Zealand and England, and another is planned in Japan later this month.

The tests, sponsored by Boeing, were initiated in response to rising petroleum prices, but also address aviation industry goals to reduce carbon emissions before a 2012 European Union deadline.

Though current aircraft design requires some petroleum in the fuel blend to ensure that engine seals work properly, the most efficient and beneficial mix of bio- to fossil fuel has not yet been determined. Chemists continue to experiment with the blend and with the plant feedstocks being used in the biofuel portion in hopes of reducing the greenhouse gases created by flight and a Boeing spokesperson hopes that biofuels play a "significant part of the commercial fuel supply by 2015."