Commercial and Off-Highway Vehicles (COHV), as the name suggests, are commercial means of transport and work. In the United States, a vehicle is designated commercial when it is registered to a company or a corporation. These commercial vehicles are involved in many activities, including pick-up and delivery services, construction work, logging and mining. Some examples of COHV are trucks, buses, light commercial vehicles (like vans), construction vehicles, agricultural vehicles and industrial trucks (forklifts).
Over the years, there has been an increase in the number of commercial and off-highway vehicles around the world. According to PTR, there were almost 30.8 million COHV sales in 2019. Most of these vehicles are still driven by fossil fuels and cause pollution when by the incomplete combustion in the diesel-engines which leads to the production of poisonous gases such as carbon monoxide and oxides of nitrogen. Infineon estimated that heavy commercial vehicles are responsible for 25% of EU traffic’s CO2 emission and so for 5% of the total greenhouse gas emissions. Coupled with the increase in population, number of commercial and off-highway vehicles are also expected to increase over the coming years. This surge in the number of vehicles will cause the CO2 emissions to rise, leading to global warming and climate change in the long run.
Increased global warming and climate change is one concern that has led to focus on electrification of COHVs but, there are economic concerns too. Total Cost of Ownership (TCO) offers a comprehensive view of the economic situation. The initial purchase price is higher for electric vehicles which is a concern for both private owned vehicles and commercial vehicles but International Energy Agency’s (IEA) analysis has shown that the TCO per km is lower for EVs as compared to traditional vehicles especially for vehicles-belonging to commercial or public service fleets with lots of utilization.
At present, the electrification of COHVs lags behind the electrification of other vehicles like passenger cars because of the technical limitations. Some COHVs like heavy duty trucks are difficult to be electrified because of range limitations since they have to travel far and will need frequent charging throughout. However, with the growing numbers of COHVs and with stricter emission regulations, charging options may become more readily available.
The State of COHV Electrification Components
Once the need for commercial vehicle electrification is understood, the next step is the discussion of the major components that comprise an electric vehicle. The on- board battery is the main energy storage and it is charged from the grid. Since the battery provides a DC output, there is an attached inverter that carries out DC-AC inversion and runs the motor (in cases where AC motor is used). In some cases, DC motors are also used and hence that setup does not require the use of an inverter. The other components of the vehicle can be synchronized with the battery by means of a DC-DC converter. There is often more than one motor and in the case of construction, garbage trucks, forklifts, a motor is needed to run hydraulics as well. Each component that is being used to construct the electric vehicle needs to be optimized in every way possible and companies are trying to work on each component. Two of the components are discussed below:
- Battery: The new battery developments by the companies include the major focus on the three main components of the battery: cathode, anode and electrolyte. For storage, Lithium-ion (Li-ion) batteries are being used and there has been research regarding the main characteristics of the batteries; such as charging time, stability and efficiency. LiFePO4 type of battery is preferred because it is chemically stable and also safe to use. Other compounds such as LiCoO2 and LiMn2O4 may have thermal and overcharge concerns.
Moreover, there is another type of capacitor, known as the super capacitor, that is used for energy storage and it undergoes frequent charge and discharge cycles. The super capacitor has become a part of battery technology by using special electrodes and electrolytes. The super capacitor can withstand 2.5-2.7V. Super capacitors have a high energy storage capability than the traditional capacitors. When a super capacitor-battery hybrid system is used, it has been shown that the peak power of the storage system can be enhanced, the internal losses of the battery can be reduced and the discharge cycle could be increased causing less current fluctuations, increasing the battery life.
Although Li-ion batteries are being used widely, there are some challenges associated them, i.e., high cost and use of additional protection circuit etc. For this reason, while improvements in Li-ion batteries are being researched, a few alternatives are looked upon as well, for example, hydrogen fuel cells. Hydrogen fuel cells are lighter than lithium-ion batteries and are also renewable, since hydrogen is abundant in the atmosphere. This makes them an attractive alternative to limited supply materials being used in other types of battery manufacture. Another alternative to Li-ion batteries is the solid-state battery. Solid state batteries use solid electrodes and a solid electrolyte making them more stable and safer than traditional lithium-ion batteries. The electrolyte material used in solid-state batteries still pose challenges so further research is being carried out before they are a part of the electrified vehicles.
- Motors: Many different types of motors, depending upon the power rating, are being used in EVs. Some examples are DC Motors, Induction Motors, DC brushless motor, Permanent magnet synchronous motor and switched reluctance motor. The DC Motor and DC brushless motor are both suitable for low power Electric vehicles. The induction motor is the most commonly used AC motor and is used in higher power electric vehicles. The permanent magnet synchronous motor is similar to an induction motor but the driving voltage is PWM (Pulse Width Modulation) generated sine wave. Moreover, the switched reluctance motor has all its phases decoupled from each other and it is better at fault tolerance. To sum up, all the above-mentioned motors are being used in EV but the most famous are the AC motors (induction motors) since they are more efficient as compared to the DC motors. . According to a paper by Parker, there is an additional new technology permanent-magnet AC servo motor. The PMAC servo motor allows users to have very high closed-loop control of speed, direction and torque. PMAC motors are very efficient (90%+), and have outstanding torque density – torque per unit size.
Trends with the Major Vehicle Suppliers
Many companies have been working on the commercial vehicle electrification and also generally on electrification of vehicles. Most of them have launched electric commercial and off highway vehicles such as electric buses, electric trucks and electric industrial and agricultural vehicles. Table 1 shows the companies that have been successful in launching electric COHVs:
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The companies mentioned above have been working on electrification of commercial and off highway vehicles, but there are still some challenges. The main challenge requires improving the battery life and the type of battery used in the electrified COHV. Many companies are competing on the type of battery that will be used in COHVs as they introduce economical batteries with lower charging times and greater stability.
For example, Tesla, at their annual Battery Day held recently, announced that they plan to manufacture their own tabless batteries which will be produced-in-house and will increase the range of the vehicles. Another announcement was the elimination of cobalt from the cathodes of the batteries and the construction of a new cathode plant. With a reduction in the cost of Tesla’s battery cells and packs, Tesla plans to build a $25000 electric car and truck production is slated for late 2021.
Other companies like Mercedes Benz partnered with Hydro-Quebec and announced the development of next-generation lithium batteries with a solid and non-flammable electrolyte. Last but not the least, there are many startups focusing on improving batteries by designing different anodes, cathodes and electrolytes. Echion Technologies is one such startup based in Cambridge, England, and in February announced that it had developed a new anode for high-capacity lithium batteries that could charge in just 6 minutes.
It is difficult to include electrified COHVs in the existing transport system without considering the recharging structure for the electric vehicles. Medium-duty and high-duty vehicles will require charging off and on frequently since they require more energy per unit mile. In addition, commercial and off highway vehicles can carry higher payload and can be short-haul, accelerating and decelerating more frequently, or they can travel great distances. Many COHVs include hydraulic systems such as construction vehicles and forklifts and these take even more energy. For this reason, there should be charging stations at appropriate locations.
The question that one should ask is whether electrification of COHV will benefit us environmentally and economically in the long run. The answer to that is not simple. It requires analysis of the trade-offs and the opportunity costs.
- Increase in electricity demand: First of all, electric COHVs would reduce the consumption of fossil fuels but at the same time increase the consumption of electricity. The IEA, in the Stated Policies Scenario, showed that the global electricity demand from electric vehicles (including two/three-wheelers) will reach 550 TWh in 2030, which is six times the 2019 levels. Although, this is a problem currently, in the long run, when more and more electric COHVs become part of the roads, companies would introduce fast charging infrastructure (with better batteries and high-power chargers) which will alleviate the problem.
- High price: The price of the electrified commercial and off-highway vehicles is high because it is a new technology. Also, the components in an electric COHV have more wear and tear since COHVs travel longer distances, and some start and stop more often compared to other electric vehicles. So, there will be a need of frequent repair. But electrification of vehicles has its own benefits which include zero tailpipe emissions, better efficiency than internal combustion engine vehicles and large potential for greenhouse gas emissions reductions especially when coupled with a low-carbon electricity sector. These factors are the major driving forces for the governments of different countries to introduce policies and subsidies for the consumers. For example, the European Union approved a new fuel economy standard for cars and vans for 2021-30 and a CO2 emissions standard for heavy-duty vehicles (2020-30), with specific requirements or bonuses for electric vehicles. In the European Union, 2020 is the target year for compliance with the CO2 emissions standards for light- duty vehicles of 95 grams of CO2 per kilometer, which has contributed to the successful uptake of electric light-duty vehicles in Europe in recent years.
Although, it will take time to resolve the technological issues with electric COHVs, in the long run, the environmental and economic benefits will outweigh any problems. As governments change their policies towards a greener future, companies are continuing to work on improve the battery life and the battery charging time. Overall, there has been significant amount of effort in the electrification of COHVs and that time when electrified COHVs will take over internal combustion-engine COHVs is not far away.