
Centre Area Transportation Authority
CATA buses are a familiar sight in and around the University Park campus and State College area. The bulk of these buses are fueled by a Pennsylvania energy source that is not crude oil. They run on natural gas (methane: probably from shale gas). Pennsylvania has both crude oil and natural gas (and of course coal). One of the natural gas fields is North of State College 50 miles or so. It is a new technology for the automotive industry (although in WWII, buses and automobiles in the UK were converted to run on natural gas when the availability of petrol and diesel was limited due to rationing). But why read about these buses, when you can see and hear me playing with them instead. Please watch the following (3:14) video:
Click for a transcript.
[Video opens with Dr. Mathews behind the wheel of a Cata Bus.] Dr. Mathews: We are all pretty familiar with these Cata Busses. And you probably mostly know too that they run on natural gas. And so why many of you are interested in seeing what the front looks like, we are going to go upstairs and show you what the top looks like. Before we do that, I want you to know that this is about a three-hundred thousand dollar piece of equipment. It is a more efficient means of transportation but only if you have more than one person in it, and with me driving that is not likely to happen. Ahhhhhh! [Camera follows Dr. Mathews to the top of the Cata Bus.] Dr. Mathews: The things I do for education. Oh, bloody hell. Well, if this were a diesel engine there would be a nice tank hidden away in the bottom of the bus. With this being natural gas, what they have done is added high-pressure methane tanks to the roof; that is why the roof is slightly elevated. This is where they store enough natural gas to run for about 400 miles. Natural gas comes from about 30, 40 miles north of here in one of our own Pennsylvania natural gas fields. It is more environmentally safe, running on emissions from these vehicles is not pollution free, but it is certainly better than diesel. It is a wonderful way of using new technology to have transportation that is even cleaner than what we currently use. [Camera view changes.] Dr. Mathews: Where did the bloody camera go? Oh, there you are. What we have here are the tanks holding the natural gas used to fuel the bus. These are composite material. They are very strong. They are designed to take impacts to prevent natural gas leak. Remember it can be flammable, or an explosive gas in the right mixture with the air. To make sure we don't have any leaks, there is actually a sensor in the cab... [The sensor flashes on the screen.] Dr. Mathews: ...and if there is one, it will be detected and the bus will be evacuated. There is a lot of fear when we go to a new fuel. We are used to traveling around with highly explosive and flammable gasoline, and somewhat less so diesel. But there is certainly a fear when you go to the gases. But these are compressed so they can hold much more gas and these cylinders here are enough to give a range of 400 or so miles. This is enough so the bus can drive around town and only get filled up but once at night. A splendid situation. [Camera view shows the back of the bus back at ground level.] Dr. Mathews: We have been inside, on top, in front, now we are going to be at the back. Let's take a look to see what is under the hood of this puppy. It is a relatively standard engine. You don't need to make many changes to make this run on natural gas, although this one was built from scratch. Running natural gas is a very nice fuel for the engine. It actually creates less wear for the engine. Do you know how you change your oil in your regular car? You put in this nice golden syrupy colored oil, and when it comes out it is jet black. That is particulates. This is not going to form that so the lifetime of this engine should be longer than the lifetime of a diesel engine. [Video ends with Dr. Mathews walking away from the bus.]
These buses are cleaner than the old diesel fleet that the buses replaced. They are not pollution free. The methane can be cleaned to remove S and other contaminants but the combustion process will still produce NOx and perhaps some CH4 emissions (methane is a greenhouse gas). The fuel switching approach is yet another method of reducing emissions (perhaps–it depends on the emission). But there are fuel choices other than diesel and gasoline. Methane is another example of an alternative fuel for vehicles.
Other alternative fuels, which we'll encounter in one form or another, might include hydrogen, methanol, electricity, biodiesel, and ethanol.