The gasoline-powered, internal combustion engine dominated transportation during the 20th century, but during the early years of the automobile it wasn't obvious that it would beat out two alternatives: batteries and steam.

The movement to cut carbon emissions and petroleum consumption has of course renewed interest in electric vehicles. But there's also an effort to revive the steam engine.

Today I got a letter (speaking of antiquated technologies) from the president of the Steam Automobile Club of America, Tom Kimmel, directing my attention to Cyclone Power Technologies, a startup based in Pompano Beach, FL. A few days ago, the company demonstrated its new steam engine, which generates 100 horsepower. The company has also posted some videos of the engine here. It can run on just about any source of heat: the sun, wood pellets, biofuels, diesel, waste heat from other engines. Basically anything that can be used to produce a head of steam. The first application would be generating power from waste heat, the company says (pdf), but the engine could also be used to power vehicles.

Kimmel writes that steam engines can run directly on biomass, without the need to convert it into biofuels, with the energy losses that this entails. But there's a reason why liquid fuels beat out the alternatives before--they store more energy. It's hard to imagine this being a real alternative--outside of some nice applications. Anyone think otherwise?

Dubai, one of the emirates in the United Arab Emirates, has been all over the news lately because it announced that its investment arm, Dubai World, won't be able to pay its massive debts in time. That might lead some to wonder whether a prominent UAE project, Masdar City--a city that will produce no carbon dioxide emissions if it works as planned--will be affected.

It probably won't. Masdar City is backed by not by Dubai, the most famous of the UAE emirates, but by the emirate of Abu Dhabi. Although less visible internationally, Abu Dhabi is actually far larger and richer than Dubai. Abu Dhabi also has most of the UAE's oil reserves, while Dubai has largely exhausted its oil and relies on real estate and other investments. So while Dubai is hurting, Abu Dhabi is doing okay.

If Masdar is hurt, I think it will be indirectly. Some experts worry that trouble in Dubai could lead to a freeze in credit markets beyond the UAE, which could hurt real estate investment generally. Although Abu Dhabi is providing funding for the basic infrastructure for the city, much of that project is supposed to be financed by outside investors, who might be reluctant to invest given a tough financial climate.

A government program to help develop hydrogen-fuel-cell-powered vehicles--a hallmark of the Bush administration--has been almost completely wiped out in the Obama administration's proposed budget.

In 2008, hydrogen technology research and development at the Department of Energy got over $200 million. That's been scaled down to about $70 million in the current budget, and that's for fuel cells of all sorts--including generating electricity for the grid, and not just hydrogen fuel cells for vehicles.

Major automakers have also recently scaled back their hydrogen-fuel-cell vehicle development, emphasizing hybrids, plug-in hybrids, and electric vehicles instead.

Hydrogen fuel cells don't emit pollutants--just water. And the amount of hydrogen that can be stored, by weight, is tremendous. But fuel cells are expensive, hydrogen is hard to come by (there aren't many hydrogen filling stations), and it's difficult to store in a small volume. What's more, the cleanest way to make hydrogen--electrolysis using electricity from renewable sources--is expensive and inefficient.

What do you think? Is it about time we abandon hydrogen-fuel-cell vehicles? Or do they still have a place in future transportation?