Category Archives: Efficiency

Fuel Cell Vehicles

Auto manufacturers, both here and abroad are scrambling to produce electric vehicles. The most successful out of the gun has been the high end Tesla model S. Others include the Nissan Leaf and BMW i3. Chevrolet will be introducing the Bolt in the near future. All these cars are whisper quite and perform well. They all however suffer the drawback of limited range on a charge and a rather long recharge time at least compared to the time to fill a tank of gasoline.

Notably missing from the cars listed above is the world’s largest car manufacturer – Toyota. They set the standard for hybrid cars with the introduction of the Prius in 2001. It is powered by a internal combustion engine (ICE) which is supported by a electric motor and battery that results in quite high mileage compared to other ICE powered cars.

Although Toyota has yet to produce an all-electric car, they seem to be hedging their bet on the development of an alternative to electric cars with batteries. In development is an electric car that runs off of a fuel cell that is powered by Hydrogen. The chemistry of the fuel cell is just the opposite of the high school CHEM class experiment called electrolysis. If you pass an electric current through water it cause the production of Hydrogen and Oxygen from the water. This process consumes electrical energy.

In a fuel cell powered vehicle, hydrogen gas is stored at high pressure in a tank. When electrical energy is needed, the gas is passed into the fuel cell where it combines with oxygen from the air to produce electrical energy. The principle is simple but in practice fuel cells are complex devices that require unique and often expensive catalysts to make the chemical reaction proceed at a sufficient rate to power a vehicle. The real advantage to this technology is the range of the vehicle between refills. It should be possible to store enough Hydrogen in a vehicle to get a lot more range than can be achieved with charging batteries.

A problem with the use of Hydrogen is one of thermodynamics. It takes more energy to produce Hydrogen than you can get back when used. Basically any time you do work, energy will be wasted. Thermodynamically work is the use of energy to drive a process, be it chemical , electrical or mechanical. In the case of Hydrogen energy losses occur when it is created from water by electrolysis, when it is compressed for transportation, when it is decompressed for use, and when it is used in a fuel cell. Each of these processes constitute an inefficiency where energy is lost.

Another problem is that Hydrogen is a gas and somewhat difficult to handle. Hydrogen stored in metal containers, or piped in metal pipes causes embrittlement. The metals become more fragile and likely to fail under pressure on exposure to Hydrogen. It is also problematic in that it has a low energy density by volume. It takes a lot of space to store a given weight of Hydrogen.

Toyota is betting that these difficulties with the production, storage and utilization of Hydrogen can be overcome.

Transportation Efficiency

Prices for transportation fuels are down for the short term but will rise, and hence the costs for transportation of all the commodities we consume will rise. Transportation costs can be reduced in a couple of ways. Reduce the distance goods must be transported and increase the efficiency of transporting goods. Additional costs to consider are things such as the impact of greenhouse gas emissions and traffic fatalities associated with each transportation modality.
Increased reliance on locally-produced foods, among other goods, is a commendable goal. Not only does this strategy reduce transportation costs, but also builds community by supporting a local economy. This can go only so far, however, as some goods simply can’t be produced locally. Oranges will still need to be shipped to Vermont and maple syrup to Florida.

Transportation efficiency is best compared by using a figure called the ton mile-per-gallon; that is, the distance one ton of freight can be hauled with the consumption of one gallon of fuel (diesel). The numbers are for barges 576, rail 414, and trucking 155. An efficiency ratio is something on the order of 4:3:1 respectively. Barges are four times and rail transport three times as efficient as trucking. Data on barge traffic is included for the sake of comparison, but inland waterways are limited to essentially the eastern half of the U.S.

Not only is trucking the least efficient and most polluting, but also the most dangerous. An interesting statistic is fatalities per ton-mile. How many people will die as a result of the transportation of goods per billion ton miles? For barges .03, rail .65 and trucking 4.35. There are about seven times as many fatalities associated with trucking compared with rail transport.

Just as barges are limited to a large degree to the eastern U.S., rail transport has its limitations. Rail networks are not nearly as extensive as the highway system plus truck transport generally results in a faster delivery schedule.

The best solution to increase efficiency, increase safety and lower pollution due to transportation would be a much better integration of rail and truck transport. The objective would be to move freight long distances by rail, then use the trucking industry for the depot to retail outlet part of the haul.

Infrastructure changes are needed to expand the rail systems, meaning greater costs, but this would be offset by lower costs for highway construction and maintenance. Transportation safety would be greatly increased by getting most of the long haul trucks off the highway, thus reducing the number of truck car collisions.

There would still be a need for the trucking industry to move goods from an expanded rail system but these trips would be made with smaller trucks and for shorter distances. Trucking jobs would be more attractive because short haul trucking means that the drivers get to go home daily. Greatly increased integration of the trucking and rail industries can result in lower costs, cleaner air, and greater safety.