You're absolutely right, gwilki. Energy density of CNG is lower than gasoline, so cars generally can't carry enough on board for long range. Most of the smaller vehicles that have used CNG have gotten a range of about 200-220 miles.
Interesting in the slideshow are the couple of times that it states that the tanks in the bi-fuel vehicles have the equivalent capacity of 8- 20 gallons of gas. Depending on the mileage that can be attained on natural gas, that does not give the potential for long trips. That may not cause grief for those vehicles that also carry gasoline and can be transferred over with the flip of a switch, but for any vehicle that is soley CNG powered, it pretty much restricts them to in-city use.
I believe that Vancouver has been using CNG busses for quite a while, but I would guess that they carry much more gas.
Note that all these vehicles are talking about using CNG, not methane.
That's a really good point, Al. There are only about 1,300 natural gas refueling stations in the U.S., and about half of those are privately owned, which means that most of us can't use them. Of course, we can put refueling stations in our garages, but the refuel time is atrociously slow in home stations -- about half a gallong equivalent per hour.
What is interesting is that there are already folks producing natural gas in the form of methane by using farmyard waste. And at least one researcher claims to be able to produce methane from garbage and other municiple waste products. Instant recycling. It could be quite useful.
Another advantage to testing the concept on city buses is that it would greatly reduce the cost to expand urban transit systems. Boston, like many large cities, has streetcar and "trackless trolley" lines, which are simply buses powered by overhead trolley power lines via a pantograph pickup. Extending the line requires extending the power lines as well. With fuel cells, the buses can disconnect from the lines and run anywhere there is a road, greatly reducing the cost to install and run new service. Expanding service could be as simple as striping the road for a dedicated bus lane, or adding a dedicated bus lane in a highway median, without the added expense of tracks and/or power infrastructure. Boston's "Silver Line" was originally designed as a low-cost alternative to a new streetcar/subway line that uses trackless trolley buses in a dedicated busway & tunnel system. Using fuel-cell powered buses would significantly reduce the cost of additional routes that must be added as part of court-ordered "mitigation" measures designed to reduce air pollution as part of the funding for the "Big Dig" highway project.
Festo's BionicKangaroo combines pneumatic and electrical drive technology, plus very precise controls and condition monitoring. Like a real kangaroo, the BionicKangaroo robot harvests the kinetic energy of each takeoff and immediately uses it to power the next jump.
Design News and Digi-Key presents: Creating & Testing Your First RTOS Application Using MQX, a crash course that will look at defining a project, selecting a target processor, blocking code, defining tasks, completing code, and debugging.
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