Over the Weekend I received a lengthy email (which I will post of the next 2 days) from Tom B. of the Clearlight Foundation advocating for Natural Gas (NG) fuel cell vehicles that talks about using compressed natural gas CNG or even liquefied natural gas (LNG) instead of hydrogen as a fuel feedstock.
I’ve decided to post the first part of the email here:
Tom B. says, “The hydrogen initiative is stalled. The hydrogen cars work fine but no good solutions have been found to the problems of where to get the hydrogen or how to deliver and store it. Very important details!
“Hydrogen tends to fly into space but natural gas is abundant on earth because methane has one carbon atom that holds four hydrogen atoms in a tight and stable cluster. Three recent breakthroughs have made natural gas a very interesting fuel.
1. Ceramic fuel cells that can make electricity from natural gas at 60% efficiency .
2. ANG: Adsorption stores natural gas at low (500 psi) pressure in compact tanks.
3. A glut of natural gas caused by new shale drilling/extraction techniques.
“The fuel cell breakthrough is particularly important because it means your car can generate its own electricity more efficiently than a massive power plant! Big plants typically average 30% efficiency, so a 60% NG fuel cell hybrid is twice as efficient as an electric vehicle charged from the grid. That means half as much fuel is consumed.
“Twice as efficient as an electric car is saying a lot because electric cars are already three times more efficient than conventional cars. This is because internal combustion engines are less than 30% efficient verses 90% for electric motors. Natural gas fuel cell cars are thus about six times more efficient than today’s cars. Using 1/6th as much fuel means pollution is also 1/6th. NG is inherently very clean. and has 30% lower carbon content so CO2, sulfur, volatiles, and NOx are even less than 1/6th.
“Since NG fuel cells have a warm up time, the hybrid batteries must have enough capacity for all-electric operation until warm up is complete. After warm up, the fuel cell keeps the batteries charged and the batteries provide power for peak loads and acceleration and recapture energy on braking. A Prius uses 16.8 kW for continuous 70 mph driving on a level road. The fuel cell must be able to supply this much power for steady driving.
“Natural gas is already distributed by pipeline to homes all over the US, so home refueling is possible. Compressed Natural Gas (CNG) is already used to run five million vehicles worldwide. Pump prices for CNG are about one third of the price of gasoline in spite of the expensive ($350k), 3600 psi pumps and fittings currently used for delivery. The pipeline cost of natural gas is only 1/4th of the cost of crude oil with the same energy content. If much simpler, 500 psi Adsorbed Natural Gas refueling is adopted, prices could be reduced even further.. Cost per mile for a NG fuel cell hybrid would currently be only 1/18th of present cars but could be reduced even further with low pressure ANG refueling!
“ANG fuel tanks contain activated carbon “sponges” that adsorb 160 times their own volume of natural gas. They can be made from Corn cobs , which have a network of nanoscale passageways that remain after carbonization. One gram of this material has as much adsorbing surface area as a football field. When natural gas is adsorbed on a carbon surface it ceases to act like a gas. Dense storage at low pressure makes it possible to hide the much smaller tank inside the car’s frame.
“So an NG fuel cell hybrid is a lot like a Chevy Volt with a fuel cell replacing the range extender engine/generator and a much smaller battery. Its battery only needs to be large enough to run the car during warm-up of the fuel cell, currently about 15 miles. The Chevy Volt’s 40-mile battery is rumored to cost $5000, so the NG car’s 15-mile battery would cost $3125 less. Incidentally, at these battery prices a 400-mile range pure electric car would need $50,000 worth of batteries! Pure electrics have other problems: A 110v, 20A household plug can supply only 2.2 kW which means that 10 hours of home charging will only take you 10 x 2.2 x 4 mi/kW = 88 miles.”
Tom B. makes some very good points. My response is that along with NG vehicles and hydrogen cars being competitors with each other and with other vehicles such as they both are with electric vehicles, NG vehicles and H2 vehicles can also be more “companion vehicles.”
The advantage that natural gas vehicles have over hydrogen vehicles right now is that there are more NG cars and buses on the road than those powered by hydrogen and there are more NG refueling stations in operation. California is a good example of this as there are around 26 hydrogen fueling stations in operation and over 200 CNG stations. Another disadvantage of NG vehicles is they are largely dependent upon a declining fossil fuel source, though landfills could be use to supply some natural gas to NG vehicles (as well as hydrogen cars).
The advantage that hydrogen cars have over NG vehicles is that H2 FCVs are zero emission vehicles and NG vehicles do emit a small amount greenhouse gases into the atmosphere. What is interesting however is that over 90-percent of hydrogen today is made by steam reforming natural gas.
This steam reforming of natural gas can also be performed at the pump level as well as demonstrated by the Honda Home Energy Station, which does this very thing. Also, India for the past 5 years has been experimenting with blends of CNG and hydrogen to see what specific blend is more efficient and less polluting. Most CNG vehicles can contain up to 20 percent pure hydrogen without modification to the vehicle and with blends over 20 percent only slight modifications are needed.
Anyway, that’s all for now as I will address the rest of the email tomorrow.