A movement led by visionary climate activist Bill McKibben, 350.org, has spearheaded the Moving Planet initiative to show how we go beyond fossil fuels while moving towards a low-carbon economy. The day (September 24th) is not exclusively fixated on mobility but has a significant focus on low-carbon transit solutions.

In light of Moving Planet, I thought it made sense to consider the top five emerging low-carbon transit technologies and some of the companies playing a key role in moving towards them. Some of the technologies are “bleeding-edge,” others are also more low-tech, but when applied globally they all have the potential to make a huge dent in our global carbon emissions.

Bike-sharing: The first bicycles were introduced in the 1800s. While many of us own one or more of these two-wheeled machines, not enough of us use them as regular means of transportation. Amsterdam and Copenhagen have garnered world-wide fame for their use of bikes, which approach 50% of all commutes. For those who live too far (e.g. in distant suburbs) from their work, having access to a bike for inter-city trips may be attractive. Thus, the rapid growth of bike-sharing systems around the globe, with more than 400 systems now in operation in Europe alone. Bike-sharing has moved across the Atlantic, with cities such as New York, Vancouver, and Boston launching programs. PBSC Urban Solutions has been cashing in on this growing trend in bike-sharing systems. Their flexible, modular BIXI bike-sharing system–complete with software and solar-powered communication systems–is now in use in 10 cities around the globe, which support nearly 15,000 bikes and 300,000 users. The next phase of bike-sharing is e-bikes. The University of Tennessee just launched a pilot e-bike sharing program, one of the first in the world.

Bus Rapid Transit (BRT): This is far from a new technology, as the first bus rapid transit was introduced in Curitiba, Brazil in 1974. BRT is generally associated with dedicated lanes, elevated bus stops to expedite exit and entry, and high frequency. When implemented correctly, BRT systems get awfully close to the ride, speed, and comfort of light rail or subway systems at a fraction of the cost. Currently there are approximately 120 BRT systems around the world. BRTs make a lot of sense because they provide the convenience of rail systems at a fraction of the cost and can move a lot of people on a daily basis. The Bogota Transmilenio serves nearly 1.5 million people daily. Obviously, this results in a significant reduction in carbon emissions–and in fact the Bogota system was the first transportation project approved by the UN Clean Development Mechanism as a carbon project. What’s next for BRT? How about electric, smart-grid connected buses? Perhaps Proterra will enter this market soon.

Electric Vehicles (EVs): Hyped for decades now, it appears the EV is finally ready for primetime. GM is back for another round now with the Chevy Volt, named the Motor Trend Car of the Year. Priced in the low $30,000 range, the Volt has raised expectations that we are finally entering the EV era after several missteps, including GM’s strange experiment with the EV1. Of course, Tesla has garnered the most media attention, first for its wicked fast Roadster and now for the Model S Coupe which goes 0 to 60 in 5.6 seconds and has a range of up to 300 miles on a single charge. Aside from EVs, many enabling technologies such as improved batteries, quick-charge stations, improved infrastructure, and the smart grid are helping to bring EVs into the mainstream. I would be remiss if I did not mention Better Place–the paradigm-shifting, billion dollar startup founded by Shai Agassi which seeks to facilitate this transition via enhanced EV infrastructure around the globe.

High Speed Rail (HSR): I love high-speed rail. I lived in Europe on two different occasions, one as a grad student at the Copenhagen Business School (1995) and the other when I took my first faculty position at the Instituto de Empresa in Madrid, Spain (2001 to 2002). I used all forms of rail transit on a regular basis for local, regiona,l and EU-wide travel. Many argue it may be too late for full-blown metro systems in our sprawled Western cities, and they may be right, but I still have hopes for high-speed rail (accompanied by local BRT and other smart transit systems). Unlike bus rapid transit systems, however, HSR is not so inexpensive compared to alternatives. President Obama and Joe Biden are advocates of high-speed rail in North America–and in fact, Obama’s most recent jobs bill seeks $4 billion in investment in HSR. However, in the current economic and political climate, I doubt we will see significant HSR developments in the next few years.