The topic of alternative fuels was scheduled for the April issue of National Bus Trader several months ago. The timing turned out to be very appropriate. We have not covered this topic in any depth since 2011 yet there have been some ongoing developments that are changing decisions.
While some people think that the topic of alternative fuels and going green is somewhat static, anyone who keeps up with what is going on will find that the opposite is true. While the developments may not be huge, they are shifting the playing field to a significant extent.
One of the most significant developments has been the ongoing changes in EPA regulations on new engine emissions every three years. This has led to clean diesel technology that has reduced the advantages of alternative fuels and put more emphasis on costs. Recent developments in Global Warming are also taking the wind out of the sails of the alternative fuel movement. With its new liquid system, propane autogas may be poised for an increase in market share. In addition, battery power may be the favorite for the future and only needs greater battery storage capacity in order to win the race.
Another important factor in this area has been ongoing developments with battery-powered buses. Complete Coach Works has had increasing success with merging a remanufactured transit bus with electric propulsion – thereby allowing operations to get into electric buses with a minimal investment. BYD has also taken a major step forward by offering a battery-powered coach. My feeling is that the only thing holding back a wholesale move to electric buses is the state-of-the-art limitations in battery capacity.
If you pardon the pun, power for public transportation has shifted over the decades for several reasons including range, cost and practicality. Other than railroads, early public transportation was tied to horses. You had horsecars in the cities and stage coaches running longer distances. Those people who talk about pollution today need to think about what the horses left behind.
While a few horsecar lines lasted into the new century, the successful streetcar system that Frank J. Sprague built for the Richmond Union Passenger Railway and put into operation in 1888 essentially marked the beginning of the end for real horse power in transit. While some might say that the streetcars were cleaner, the real reason for the switch to trolley cars was the lack of range, lack of speed, potential for disease and cost of running the horses. The trolley cars also had an advantage in providing more capacity.
Electricity soon become the preferred power for city transit and, with the electric interurban railways, also served many suburban and intercity customers. Electricity dominated city transit for at least four decades and in some cases was used to power trolley buses that replaced some of the streetcars.
There are people who suggest that the move from streetcars to buses was engineered by bus builders, tire manufacturers and other industry suppliers. There is a book titled From Railway to Freeway by Eli Bail that covers this topic. However, buses had already started to replace streetcars in early years for various reasons. The most obvious was that buses were more economical for routes with less patronage such as feeder routes, crosstown routes and extensions into suburbia since they did not require the costly infrastructure of rails and overhead wires.
Due primarily to Detroit Diesel, the larger buses began moving to diesel power in the late 1930s. By 1960, all coaches were diesel powered as well as all but the smallest transit buses. I should point out that alternative fuels are not new in bus applications. Back in the 1950s, the Chicago Transit Authority operated very few diesel-powered buses. Smaller buses were powered by gasoline while the larger buses were primarily trolley buses or powered by propane. The propane was chosen at that time because of its attractive operating costs rather than because of any ecological consideration.
The movement to alternative fuels escalated in recent years because of interest in improving the environment. Surprisingly, in spite of all of the publicity and number of options available, the alternative fuel movement was very limited. U.S. transit fleets were still more than three-quarters powered by diesel engines and the only alternative fuel to get significantly beyond one percent of use was compressed natural gas. Following is a review of recent developments and the current status of various fuel alternatives.
Global Warming and Clean Diesel
Back in 2009 it was disclosed that the leading proponent of Global Warming, the Climate Research Unit at East Anglia in the UK, was fudging their numbers. More recent research has shown a similar pattern at other climate research locations around the globe. In effect, the errors were all on the side of showing increased temperatures, thereby multiplying Global Warming several times over. Another report shows that the reduction in polar ice is due primarily to a shift in a warm Atlantic current, and reflects a similar situation that was even worse 40 years ago. As a result of all of this, many people now use the term Climate Change rather than Global Warming.
Moreover, it has also come to light that carbon in our upper atmosphere is only about 350 parts per million, far too small to hold anything back. Data from the satellites show that heat is not being held in on the earth but is escaping. Hence, even if there is some Global Warming, it is not man-made and the result of emissions. All of this has taken some of the wind out of the sails of the alternative fuels and environmental movement.
I hasten to add that while evidence showing man-made Global Warming is disappearing, there are still reasons why it is a good idea to clean up our act. For example the ports of Long Beach and Los Angeles have restrictions limiting trucks to 2007 or newer model year engines and other requirements. This has resulted in an 82 percent decrease in diesel pollution at the Port of Long Beach.
What this reflects is a tremendous reduction in diesel engine pollution in recent years. Because of ongoing EPA regulations, our new diesel engines have become clean and cleaner. Those in the industry are calling this Clean Diesel technology. There is even a movement underway to look at cleaning up older engines. This is having a major impact on alternative fuels.
When you compare clean diesel emissions with CNG emissions, there is increasingly little environmental advantage in going with CNG. When you add in the reduced impact of man-made emissions on Global Warming, it substantially reduces the advantages of alternative fuels. As a result, alternative fuels are increasingly being forced to show a financial advantage since any environmental advantage is now less important. It will be interesting to see how this plays out in the future.
Reducing Fuel Consumption
There are three popular ways I know of to reduce fuel consumption. They include ethanol, biodiesel and hybrid systems.
Ethanol is essentially ethyl alcohol that is blended with gasoline to reduce the use of fossil fuels. It can be produced from agricultural feedstocks including sugar cane, potato, manioc and corn. The United States and Brazil lead globally in ethanol production and account for about 88 percent of the world’s production.
While ethanol does represent an alternative to fossil fuels, it does have its limitations. Most gasoline engines can handle a blend incorporating 10 percent ethanol (E10). However, higher percentages typically require engines built for ethanol or flex-fuel.
In Brazil, where ethanol typically comes from sugarcane, ethanol has been blended with gasoline since 1976. Currently, Brazil uses a blend of about 25 percent ethanol (E25) but there are autos, light trucks and motorcycles in Brazil running on pure ethanol (E100). In the United States, where ethanol typically comes from corn, there are detractors who point out that using corn could raise food rices and that the process of extracting ethanol from corn may require more energy than what the ethanol saves.
While ethanol has proven to be a viable replacement for gasoline, its future may hinge on developing sources that are less prone to impact food prices or require substantial energy to produce. Its uses in public transport are limited other than some small buses that run on gasoline.
Biodiesel is a clean burning alternative fuel added to diesel fuel to reduce the use of fossil fuels. Chemically, biodiesel consists of mono-alkyl esters of long fatty acids derived from vegetable oils or animal fats. In the United States, biodiesel is often made from soybeans. Those who have used it say that both performance and fuel economy were unchanged with biodiesel but that exhaust emissions improved and eye irritation virtually disappeared. Some people have said that biodiesel exhaust smells like french fries.
Pure biodiesel is not compatible with natural rubber since it technically is a solvent. However, this has not been a problem with a 20 percent blend (B20) or less. There are indications that engines can run on pure biodiesel (B100) but that modifications are necessary. I know of at least one local bus company experimenting in this area.
Canada started adding biodiesel content in both diesel road fuel and home heating oil in 2011. Continued popularity will probably depend on several factors including improved production methods and costs.
The standard hybrid systems are based on the premise that most of the horsepower in your engine is used for acceleration. Once you have attained your regular cruising speed, your need for horsepower is substantially less. What the standard hydrid systems do is to use regenerative braking to capture energy during braking to use if for acceleration later. This allows you to use a smaller engine, thus saving on fuel and pollution.
Your typical bus hybrid system incorporates a smaller engine with an electric motor and a battery or other electrical storage device. When the bus driver presses the brake pedal, the bus goes into regenerative braking mode. Energy from the speed of the bus is converted to electrical energy that is stored in the battery. When accelerating, that same electrical energy turns the electric motor and assists the smaller engine.
It should be noted that hybrid systems work best with stop and start operations like transit buses and some shuttle services. They are not appropriate for non-stop services such as charters and tours. In addition to conventional transit operations, hybrid systems have also been used on small buses and on?MCI commuter coaches.
Due in part to reduced pollution from the new clean diesels, hybrid systems may be losing popularity. In the summer of 2014, New York City announced that it would remove a quarter of its 1,677 hybrid buses from the city streets and replace them with clean diesel models. The point is that the new clean diesels are equal to or better than hybrid technology of only a few years ago.
True Alternative Fuels
Reality is that in the United States, the only alternative fuel that ever caught on in serious numbers was compressed natural gas (CNG). The 2013 data from the American Public Transportation Association covering U.S. public transit fleets showed that 77.71 percent of the buses were powered by diesel fuel. CNG came in second at 19.90 percent. Third was Liquid Natural Gas (LNG) at only 0.96 percent. Then, in order, hydrogen at 0.20 percent, electric at 0.11 percent, gasoline and electric at 0.10 percent and propane at 0.08 percent.
All of these alternative fuels are now faced with the fact that they offer less of an ecological advantage because diesel has become so clean. The ones that survive will probably have to offer some financial advantage. Here are some thoughts on a few of the alternative fuel options.
Hydrogen Fuel Cell
At least on the surface, hydrogen fuel cell buses appear to offer several advantages. A major reason for this is because hydrogen is plentiful?– more than 70 percent of the earth’s surface is covered in water, which contains hydrogen. A second advantage of hydrogen is that it is easy to obtain since you do not have to buy it from a fuel supplier. Most of the fuel cell bus operations make their own hydrogen. A third advantage of hydrogen is that while it is flammable or explosive if concentrated, it disappears quickly in the event of a leak because of its light weight.
Hydrogen is carried on fuel cell buses in tanks, similar to compressed natural gas. However, instead of a motor, the hydrogen is fed into a fuel cell where a chemical reaction takes place. The hydrogen atoms combine with oxygen from the air to release electrons for electrical energy and create water. Hence, the electrons power the bus while the “exhaust” is merely warm water. Hydrogen fuel cell buses will typically also use regenerative braking to conserve energy and a battery to store the electrical energy.
Hydrogen fuel cell buses have been in operation in several cities. AC Transit, on the east side of San Francisco Bay, began experimenting with a small hydrogen fuel cell bus in 2003 and expanded into full-size buses. Other operators included SunLine transit in Thousand Palms, California, and CT Transit in Hartford, Connecticut. More recently, 12 more fuel cell buses were put into operation in the San Francisco Bay area.
On the one hand, the reaction of drivers, passengers and operators has been positive. On the other hand, we have not seen wholesale conversions of transit fleets to fuel cell. It has been suggested that the initial cost of fuel cells plus ongoing replacement costs currently makes this technology costly. Fuel cells could become more popular if ways are found to make them more economical.
Compressed Natural Gas
If any one type of alternative fuel has been a winner in this going green movement it is CNG. Natural gas, supplied through underground pipes, is typically used for heating and cooking in metropolitan areas. Due to storage space concerns, the natural gas is compressed into tanks which are carried in the buses, often on the roof. CNG has become the most popular alternative fuel in U.S. transit operations and accounted for 19.9 percent of US. transit fleets in 2013 according to APTA.
On the one hand, CNG technology is tried and true. Unlike most other alternative fuels that are still somewhat in the testing stage, CNG buses are currently in operation for numerous transit agencies throughout the United States in sizeable numbers. Los Angeles was recently operating more than 2,000 CNG buses. In addition, CNG power is also available for smaller and mid-size buses. MCI also offers their commuter coaches with CNG power.
On the other hand, the advantages of CNG are disappearing in the face of improved clean diesel alternatives. A recently study compared a 2012 CNG bus and a 2012 clean diesel bus with an older 2000 diesel bus. In comparison to the 2000 diesel bus, the 2012 CNG bus had 100 percent less hydrocarbons while the 2012 clean diesel had 89 percent fewer hydrocarbons. In particulate matter, the 2012 CNG bus showed a 99 percent improvement over the 2000 diesel bus, but the 2012 clean diesel was not far behind with a 98 percent improvement.
Moving to nitrogen oxide emissions (NOx), the 2012 CNG bus had an 80 percent improvement over the 2000 diesel bus while the 2012 clean diesel showed an impressive 94 percent improvement over the 2000 diesel bus. Hence, with today’s clean diesel technology, CNG has considerably less of an advantage and at least in one area the new clean diesel engines are actually better.
What will probably happen moving into the future is that decisions on alternative fuels will be based more on a comparison with clean diesel and on overall costs. Many operations that use CNG do report fuel cost savings.
Years ago, propane (now called propane autogas) was the leading alternative fuel for buses. Today, it is the leading alternative fuel worldwide. In addition to a substantial propane fleet in Chicago many years ago, propane was used elsewhere including some suburban companies. What is interesting is that the primary reason for the use of propane at that time was financial and not ecology.
Propane is used for heating and cooking in many if not most rural areas in the United States. It is also available at most campgrounds since it is used for heating and cooking on most recreational vehicles.
Propane autogas is going through somewhat of a rebirth. The recent introduction of liquid propane systems has made propane more practical and more economical as a fuel. Propane-powered buses were obvious at the recent BusCon show in Indianapolis and even Freightliner showed a propane-powered chassis. You may well see more use of propane autogas in the future simply because of its economy.
Unfortunately for propane autogas, one of its biggest advantages is also one of its biggest disadvantages. Propane works well in gasoline engines. In fact, you can switch between the two fuels without missing a heartbeat. Since larger buses? typically no longer use gasoline engines, propane is less appropriate for those ?vehicles.
I have left electric buses for last because of recent developments and increasing interest. Years ago we had trolley buses in many cities that operated solely on electric power. Most of those are gone. Today when we talk about electric buses we are primarily looking at buses operating from battery power. All or virtually all of these will also use regenerative braking to increase their range.
From the positive standpoint I continue to see increasing interest in battery-electric buses. Why not? There is essentially no pollution from bus operation, although how your electricity is generated could make a difference. Many of the people I have spoken with suggest that the cost for electricity to move a bus is or should be less than using fossil fuels. In addition, the battery bus has several advantages in maintenance and service since it does not require an engine or transmission nor things like fuel and oil filters, antifreeze, a block heater and a couple other things. In the winter months you simply turn a switch, build up air and go.
Frankly, I would expect to see a wholesale movement to battery electric buses except for three things. The first is recharging time. Recharging a battery bus overnight is generally not a problem. However, some operations require shorter recharging times to make the electric bus practical. There have been some improvements in charging systems recently that are making major progress in this area. However, any type of full battery recharge still takes more time than refueling a bus with diesel fuel.
A second problem area has been more difficult to address. In spite of recent developments, current batteries are still somewhat limited in the electrical charge they can store. This tends to limit the driving range of battery electric buses to less than that needed for some applications. Electric buses have long ago given up the lead acid starter batteries found in most buses. They weigh too much for the charge they carry. Battery-?powered buses today more typically use some type of lithium ion battery, sometimes incorporating ferric (iron) or phosphate involvement. Their advantage is being able to hold more electrical charge with less weight. Their disadvantage is that they are costly and may lose some of their charging capacity as they grow older.
The third disadvantage of battery-?powered buses is their costly battery systems. If someone could figure out a way to increase battery capacity while decreasing cost, it would make a huge difference in the movement to battery buses.
How do you deal with the lack of battery capacity? One very obvious and popular option is the use of regenerative braking. When the bus driver hits the brakes, the energy from the turning wheels is transformed into electrical energy and used to charge the bus battery system. That energy is then used to help accelerate the bus. This works well in transit and commuter service with its multiple stops but would be of little value in charters and tours.
Beyond this, there have been several other options offered with varying degrees of success. Proterra has a system to charge buses at the end of the line that has worked with some degree of success. Siemens Electric in Germany was working on a system that would use an overhead charging system at bus stops to charge batteries while passengers are boarding and leaving the bus.
Canadian manufacturer Bombardier has a system that creates a magnetic field in the roadway that charges the bus battery system using an inductive energy transfer. It worked well in a trial with a streetcar in Germany. However, both of these systems have the same problem as the old overhead wires, the bus would have to stay on a fixed route.
There is obvious movement towards battery electric buses. Some examples of smaller buses like cutaways powered by batteries have been displayed at BusCon but are yet not in widespread use. Many of the big transit bus builders, both domestic and foreign, are working on offering a battery-powered bus. Available from ZF for quite some time is their AVE 130 portal low-floor axle with water-cooled asynchronous electric motors in the axle hubs. Some manufacturers, including the Bozankaya Sileo model from Turkey, already have workable battery electric buses available using the ZF axle.
Meanwhile, the new battery systems have reached a point where their capacity has enough range for some transit ?applications. As a result, we are now seeing battery-powered buses in actual transit service.
The ZEPS Bus
One of the more interesting and more practical recent developments is the ZEPS (Zero-Emission Propulsion System) bus from Complete Coach Works. Located in Riverside, California, CCW has an enviable reputation for rebuilding buses and other vehicles to make them more valuable and extend their useful life. Their sister company, Transit Sales International, is well-known for offering pre-owned transit buses.
What CCW did was to combine the talents of both companies by taking a pre-owned transit bus and rebuilding it in such a way to make it better suited to electric operation and then install a battery electric drive system. The resulting ZEPS bus offers a like-new vehicle with battery electric power at a substantial cost savings. It provides a double-ecological advantage by avoiding both the costs and pollution involved with building a new bus while putting a bus on the street with a clean battery electric drive system.
CCW starts with a standard, low-floor 40-foot bus with air suspension, an air door, air brakes, capacity for 36 passengers plus standees and a GVW of 37,930 pounds. The resulting bus eliminates landfill pollution and is only half the cost of a new bus. The remanufacturing process is so detailed and complete that the bus is issued a new title and current year registration. Because CCW makes a point to source as many USA parts and components as possible, the bus is “Buy America” Compliant.
To the best of my knowledge, the CCW ZEPS bus is unique. No other company I am aware of offers a remanufactured battery electric bus at a reasonable price. For more information, see the article in the December, 2013 National Bus Trader.
ZEPS buses have been in service in several places including the University of Utah and the University of California. They have been put into test service at Ben Franklin Transit in Washington State and elsewhere. The latest news is that 21 ZEPS buses are being put into service at the Indianapolis Public Transportation Corporation (IndyGo) in Indianapolis. Remanufactured battery-powered buses are now operating in fleets.
A relatively young company, BYD became a major manufacturer of rechargeable batteries. When they purchased an auto builder, it was only natural for them to expand their product line to include a dual mode and then an electric auto. From there they went into offering electric buses.
In 2010 BYD developed a 12-meter (nearly 40-foot) low-floor battery electric transit bus using BYD’s own iron phosphate batteries and their drive axle that incorporates two electric motors in the hubs. It has a top speed of about 60 miles per hour and a range of about 155 to 185 miles depending on the type of service. Hundreds are now in service in China and orders have been received from around the globe. At latest count, more than 2,500 are in service and there are orders for more than 2,000 more. This is easily the most popular battery electric transit bus in the world.
It is noteworthy that BYD recently introduced a battery electric intercity coach at the United Motorcoach Association Motorcoach Expo in New Orleans in January of 2015. It is being offered in lengths of 23, 40 and 45 feet and has a range of up to 190 miles. While the range falls short of what is needed for charter and tour operations, the coaches could be used for some local services including shuttles, city tours and commuter service.
The coaches have essentially the same features as diesel coaches and are optionally available with restrooms and wheelchair lifts. So far the battery electric coaches have been built at the Changsha facility in China, but they could be built at the BYD factory in Lancaster, California.
At this point it is obvious that as of 2015 there are two major trends in alternative fuels. One is that the substantially reduced emissions from clean diesel technology has eliminated much of the advantage of reduced pollution from alternative fuels. In the future, the cost of alternative fuel operation may be a bigger factor in making fuel decisions. A second trend is the obvious pressure to move towards battery electric buses. Any technological advance that would allow batteries to carry more of an electric charge or reduce their cost would result in more movement to battery electric buses and coaches.