Airships!

In case you're not aware, airships are potentially much cleaner than flying in planes (potentially 80-90% less CO2) and could provide the best viable alternative for Atlantic crossings . This Forum for the Future post gives a rough idea of what this future travel technology could be like but there's plenty more work to be done to work out how viable it really is. Also, what with western governments ploughing ahead with short-sighted airport expansion it's not exactly crystal clear where airships would take off from (could existing airports be modified?).

But before we tackle the issue of airport expansion head on (which is what the people at Plane Stupid are great at) let's try and work out the carbon issues and how far this could feasibly scale up before it's still unsustainable.

I've come across some people in California who are actively campaigning to get an airship off the ground in the San Francisco bay area in Autumn (or 'Fall' to them) 2008. Airship Ventures seem like a jolly bunch, and they are clearly serious about it - seeking investment with an impressive list of individuals involved. However, they don't seem to be attacking the venture from an environmental perspective (something they aren't really in a position to do as - somewhat predictably - a lot of the people involved enjoy flying private jets). The closest they get is mentioning biofuels in a blog post but as the more informed of you out there will be aware, biofuels are a far from straightforward win in terms of climate change. George Monbiot and many others have gone as far as to say biofuels are worse than fossil fuels.

Let me say at this stage that I was rather confused to find a post about biofuels at all, as I had thought that the environmental rationale behind airships was that they run on helium, not on the combustion of conventional liquid fuel. Then my incredibly non-physics-oriented brain realised that they need to use a combination: the helium keeps the thing in the air (like the balloons you used to inhale from to make your voice silly as a 14 year-old at Pizza Hut) whilst the fuel (be it biofuel or otherwise) propels it along.

Given that Airship Ventures seem to be the most advanced company looking feasibly at the renaissance of airships, I thought I would investigate their claims a bit further.

So given that they need to burn liquid fuel as part of the process, does this spell the end of airships as a viable low carbon alternative to conventional aeroplanes? It's not yet clear. The Zeppelin that will be used for the Airship Ventures project runs on Avgas and it's mentioned on the site that it uses 50kg/hour ("low" compared to aircraft and helicopters). However, the wikipedia Avgas article says "environmental and cost considerations have led to increasing numbers of aircraft being fitted with highly fuel-efficient diesel engines; these ... run on jet fuel [as opposed to Avgas]."

So if we assume that Airship Ventures' comparison is with other aircraft that run on Avgas, it's still unclear how the Zeppelin compares to conventional aircraft (e.g. a Boeing 747) on a kg of CO2 per passenger mile (kg CO2 ppm) basis. Then of course there are the implicit assumptions in the Forum for the Future article: "They are fitted with efficient solar cells and the latest in battery technology for propulsion, and for buoyancy rely on a combination of helium and propellers." I previously worked for a company commercialising related technologies and I'm far from convinced that the photovoltaic cells plus energy storage solution will become technically feasible. Even without the new advances, it should be possible to get a comparable figure per passenger kilometre for the current state of the art.

Notwithstanding the lack of this figure, there is still the problem of how much helium the world has left (i.e. not much). Assuming that some people with more scientific knowledge than me can turn their thoughts to to the technical challenges of increasing renewables, and overcoming the lack of helium (if it doesn't get burnt we surely don't need a never-ending supply like we do with kerosene?), then I reckon this is worth continuing to look into. I'll leave you with a picture of a ludicrously decadent conceptual design for the future of eco-travel.