At EcoGeek, we are big fans of airships. A recent article at Txchnologist asks whether airships are poised to make a comeback in the commercial sector, but other recent articles question whether they truly make sense. Are airships a realistic possibility?

Writing a commentary about his own article, author John Rennie asks if airships really offer the benefits we like to think they do. Another recent Scientific American blog post is even more critical of the idea of airships for transport.

One of the eternal tradeoffs in transportation is the time versus energy cost consideration. On one hand, there is the cost of energy to move goods from point A to point B. Faster takes more energy, and is therefore more expensive. On the other hand, the time for a pilot or driver or other person to convey the goods has to be paid for, and a longer trip means more expense. The trick is to find the balance point between the two. This is, at least to some extent, what has driven the avaition industry away from propeller aircraft to the use of jets.

Trains are very efficient for moving heavy cargo, but train tracks don't go everywhere. A hybrid train and airship network might be useful to extend the reach of the current rail network without the expensive and difficult process of laying lots of new track. Trucks serve as the spokes for these networks right now. They are more expensive at moving freight than trains, but also more flexible. Is there room for that in the current transportation network? That seems to be one of the crucial questions. And, for now, the premium for trucks is not so high that other options are being sought.

The Scientific American article particularly focuses on speed versus cost as a tradeoff, but those are not the only factors that are relevant in considering airship, so the many current military developments are overlooked. Most present military uses under development are for long duration missions, where the simple lift of the airship makes it far more economical to operate than having conventional fixed-wing aircraft.

It may be many years before old, used military airships begin to be adapted for civilian uses, but we remain optimistic that airships will become a useful contributor to part of the transportation infrastructure of the future.

An infographic created by the White Roof Project, an initiative that wants to help cover the world's black roofs with white paint, illustrates some impressive statistics about the power of white roofs, including the fact that the transition from black to white roofs could prevent the emission of 24 billion metric tons of CO2, the same amount of CO2 emitted globally in 2010.

The project says that if we covered just 5 percent of roofs with white paint per year, we'd be done by 2030. White roofs can reflect 85 percent of sunlight compare to 20 percent for black roofs and buildings with white roofs stay up to 35 degrees cooler, which means less electricity required for cooling the buildings.  In large cities, white roofs also curb the heat island effect, cooling the city as a whole.

In addition to the emissions savings, white roofs could save 14 power plants' worth of energy in 11 large cities, save $5 billion in energy costs in the U.S., reduce smog, blackout risk and heart-related deaths and Bill Clinton has said it's the quickest, cheapest thing we can do.  So, what are we waiting for?

If you live in NYC, you can volunteer for the White Roof Project or adopt a building.  The project plans to cover the roofs of an entire East Village block in white paint this August.  You can view the entire infographic here.

via GOOD