Virgin Airlines and its flamboyant founder and CEO Richard Branson were getting a lot of media attention this week for the first flight of an airliner using biofuel. Let's add some caveats, though. First, even though it was a Virgin Boeing 747-400, and it flew from London to Amsterdam, it wasn't a real commercial flight, since it only had 5 people on board. And second, only one engine (of four total) was running on the biofuel, which was a blend of about 20% coconut and babassu (a Brazilian nut) oil and 80% regular Jet A kerosene. Was this a real breakthrough in alternative fuels for aircraft, or just a good publicity stunt from media-savvy Branson?  Put this one in the publicity stunt column. With all the attention global warming has been getting recently, airlines and the aerospace industry are starting to get more scrutiny about their contributions to carbon emissions. I think Branson is trying to be pro-active in helping the airline industry answer the critics, so we shouldn't be surprised by this demonstration flight. Even though most experts calculate that aircraft only contribute about 2% of the total carbon emissions generated on earth, the airline industry is still very visible to the general public, so it behooves them to show that they are at least investigating alternatives to non-renewable fuel sources. I just wouldn't have hyped it as much at this very early stage of development. The airline industry has to be careful they don't give people unreal expectations about the availability of biofuels for aircraft use.

Unfortunately, I think aircraft will probably be the last mode of transportation to make the switch to alternative fuels/power sources. Although biofuels are a renewable energy source, one gallon of biofuel produces less energy (work) than one gallon of regular jet fuel. So that means if you fill an existing aircraft fuel tank completely with biofuel, you either are going to fly slower or a shorter distance, neither which makes airlines happy. If you want to produce the same speed and range, that means bigger fuel tanks, which for the same size wing, means fewer revenue-paying passengers. As you can see, with biofuels you don't get something for free, there is always a trade off. Not to mention the recertification and testing procedures that aviation regulators such as the FAA will require before an airliner carrying passengers can fly completely on biofuel. We are probably talking at least 10 years in the future, in my estimate, before you see a commercial flight flown completely on a biofuel.

Now having written all this, I'm not completely down on Virgin (and Boeing, who added technical expertise) for this flight. They should be commended for at least starting to look at Jet A alternatives.  Other potential aircraft power sources, such as hydrogen and electric power, are much further in the future, due in no small part to the large weight penalties these technologies demand. (Like diet guru Richard Simmons, keeping unnecessary weight off is a never ending battle for an aircraft design engineer.) Better for the airlines and the aerospace industry to start thinking and planning and testing right now for a future where they may no longer have the choice of which fuel to use because of possible environmental restrictions. Until we find that magic elixir that is renewable and clean to power our aircraft, the aerospace industry will have to be content to make aircraft fly further on less fossil fuel through evolutionary advances in aerodynamics, propulsion, and structural material efficiencies.