Where is Progress Taking Us with Respect to Batteries and Public Transit?
In our last issue of this newsletter, your Ride On writers discussed different types of electric batteries. Today, we go further on this topic with considerations of other types of batteries — such as hydrogen fuel cells — while also discussing why fully fossil fuel-consuming buses are being traded for buses that use batteries to varying ways and degrees. We then advance this discussion to look at the types of batteries buses use, how they are used, and what advances have been considered when it comes to optimizing our employment of batteries and the resources we have within the public transit system.
The first study we review was written by Jelti et al. (2021), who “present an environmental life cycle assessment of alternative buses, including hybrid (diesel-electricity), electric, and fuel cell buses at a city level in Oujda, Morocco”. The authors argue these buses generally have a propulsion system — a system that generates a driving force — operating in a series or parallel, with a combustion engine and a traction (or power) battery.
Not only do the systems employed in hybrid buses run more efficiently, but another aspect that saves the vehicle fuel is its regenerative braking system which obtains more energy by changing its kinetic or moving energy to electrical energy. Hybrid buses having regenerative braking enables the battery to charge itself, so it can go on substantially longer trips than it otherwise could, meaning it can better handle the sparsity of charging stations. This study also highlights that, compared to diesel buses, electric buses generally have regenerative batteries, are quieter, and emit less air pollution.
Going back to the point about the distance electric vehicles can travel before needing to be recharged, and the insufficient number of charging stations, this is where hybrid buses have a significant advantage compared to electric vehicles and diesel. Hybrid buses generate less pollution than diesel buses and, at the same time, can travel longer trips than electric buses. Moreover, this research importantly points out that fuel-cell buses are ideal for cities that have a lot of hydrogen. More specifically, it is only ideal for cities that have access to large quantities of hydrogen because hydrogen production is extremely costly; at the same time, buses using fuel-cell batteries emit 47% less carbon than diesel counterparts.
Taking all of the above factors into consideration, these researchers were trying to evaluate the best alternatives for buses based on their three stated criteria for evaluation, which are stated below:
Damage to human health, such as substances that cause climate change, ozone depletion, carcinogenic effects, respiratory effects, and ionization;
Damage to ecosystem quality, which includes acidification, ecotoxicity, eutrophication, and land use;
Damage to resources that includes the use of primary resources and fuels.
The authors conclude that compared to electric and diesel buses, hydrogen fuel-cells and other types of electric buses — in the tank-to-wheel stage — use less oil, but electric buses use more coal during the well-to-tank period. In the well-to-tank phase, fuel-cell and other types of electric buses do not emit greenhouse gases. In addition, electric buses emit fewer amounts of nitrous oxide, sulfur oxide, particulate matter 10, and particulate matter 2.5 than diesel buses, but more than hybrid buses in the well-to-tank phase. In the tank-to-wheel moments, both hydrogen fuel-cell and other types of electric buses do not emit nitrous oxide, sulfur oxide, carbon monoxide, and volatile organic compounds.
One of the final vital points that this research intimates is recommending the positive environmental aspect of employing a bus rapid transit (BRT) system, and that it might be worthwhile for scientists to improve fuel-cell batteries for buses, especially buses linked to the BRT system, as it is a very environmentally friendly means of transit. Buses linked to the BRT system may benefit more than your other buses from fuel-cell and hybrid buses because these buses — compared to other city buses — are in motion for the longest periods of time which allows batteries to work better. With respect to vehicles employing hydrogen fuel-cell batteries, this research seems to suggest cities with an over-abundance of hydrogen gas, such as Oujda, Morocco, can benefit economically from exporting the hydrogen gas needed for fuel-cell batteries.
The previous observations of the study above and some previous ones mentioned in our past issue of this newsletter largely considered cities in warm climates. On the contrary, Grigorieva and Nikulshin (2020) consider the cold climate city of Moscow, Russia. This research infers that regarding electric buses, it is impossible to consider them to be emitting no pollution when they are running in cold climates, including air pollution, unlike in warmer climates where it is especially eco-friendly.
One problem with electric buses is charging stations are rare, and it takes an average of 30 minutes to charge a bus for it to travel for 40 minutes — which is a significant time cost considering they do not have the ability to heat the bus in the winter, which is a real problem in northern cities like Moscow for a significant portion of the year. Simultaneously, buses with a diesel interior heater — which both diesel and electric buses have — consume roughly four litres per hour just to heat the buses when it is -10 degrees Celsius and below.
Still, the authors argue that “compared to buses with a diesel engine, electric buses consume less diesel fuel in winter and are undoubtedly more environmentally friendly.” That said, some of the expenses of employing electric buses are difficult to compute, such as the cost of charging stations, efficient electrical networks, the cost of the electricity consumed, and expenses related to the batteries, in its construction, maintenance, and destruction in the end.
In addition, as addressed in our previous issue of this newsletter, the cost of creating batteries used in vehicles — especially the human cost — is significant, which is why this paper implies that in some circumstances modern trolleybuses might be a better option than electric buses: they are three times cheaper and the batteries they require are significantly smaller.
If electric buses emit some pollution in cold cities like Moscow, one might wonder why they even consider electric buses in the first place. Well, some of the answer to this question comes from the fact that in Moscow, “about 90% of all harmful emissions into the atmosphere are accounted for by road transport with internal combustion engines.” Also, scientists are still working to advance technology related to the creation of electric buses, as well as charging stations and electrical networks.
As implied above, it is worth looking more into trolleybuses. In this direction, Bartłomiejczyk and Połom (2021) inform us trolleybus transport is used in 280 cities around the world. These buses are powered by overhead (electrical power) lines, hence the batteries required for them can be smaller, enabling more room for passengers, and less operating costs as they are lighter. In addition, the toll taken on by the wheels and suspension is also significantly lower. Moreover, trolleys no longer have a need for backup diesel generators because battery technology — now lithium batteries — has improved so much, and they can travel for a substantially longer distance now.
Of crucial importance is today’s modern “electric public transport systems are dominated by electric buses and trolleybuses equipped with lithium onboard batteries, which are smaller and significantly extend the range that can be covered without the overhead lines (due to higher capacity), but most importantly, those batteries have [a] much longer life expectancy and are less affected by charging cycles”. What this means is these trolleybuses, compared to electric buses, are cheaper to run, less dependent on cadmium, can travel for a much larger time without needing to charge, and can move faster. These trolleybuses have a much longer range because they have overhead (electrical power) lines supplying trollies with the energy they need to move and they have traction batteries that allow them to charge while in motion. Additionally, because their batteries are smaller than those of electric buses, they can take on more passengers.
This research also pertinently acknowledged Hradec Králové, a public transport authority in the Czech Republic from 1994 to 2001, who made several observations and suggestions and the topics broached included the following as stated below:
Designing optimal routes to eliminate driving on battery under the OHL—providing the pantographs on the first stop
The trolleybus stops infrastructure to enable connection to the OHL (sufficiently long bays, marked stopping area);
OHL connection point to eliminate possible collisions with other trolleybuses (installing the so-called guide caps on the exterior network lines if there is more than one connection point at the stop);
Training drivers and eliminating excessive use of the onboard batteries.
In one city with trolleybuses, the authors note the lack of slipways needed to guide the trolleybuses so they move safely. Also, there needs to be enough well-designed and long stopping areas for trolleybuses to better enable the overhead lines to connect with the pantographs which send energy to the trolleybuses, and to make it easier for trolley buses to stop and for its passengers to board. Furthermore, they also seem to suggest that trolleybuses consume less battery power than e-buses in the same road, traffic, and weather conditions, warm or cold.
Moreover, as trolleybuses have demonstrated the ability to even travel to places with which e-buses have difficulty, there is a resurgence in their popularity in many countries in Europe. Finally, as the batteries are harmful to the environment in their creation and destruction, with the batteries in trolleybuses being smaller, and therefore requiring less metal to create and last longer, trolleybuses are the more ecologically responsible option between the two.
In the end, we may draw a few conclusions. First, from Jelti et al. (2021), we perceive it is very good to employ buses and other vehicles that generate energy from electric batteries and, particularly, fuel-cell batteries in warmer climates vehicles.
Second, the research by Grigorieva and Nikulshin (2020) makes it clear it is crucial for us to constantly progress with our ideas around more eco-responsible means of getting around as this accounts for a significant portion of greenhouse gases. It is such a critical issue presently that even in cities far north, like Moscow, are finding ways to minimize their use of fossil fuels with the help of batteries.
Finally, Bartłomiejczyk and Połom (2021) has us think about buses employing fuel-cell batteries — which are likely more apt in hydrogen-rich cities — or other types of electric batteries, and how these buses can run in the most efficient and environmentally friendly. Their research on this topic suggests it may be of crucial value to research further with respect to the benefit of switching from e-buses to modern trolleybuses, which derive power and energy from batteries — whether fuel-cell or lithium — while being assisted by overhead (electrical power) lines.
The favouring of modern trolleybuses where it makes sense to have them over e-buses when it comes to public transit, particularly as part of the BRT system, comes from their ability to travel comparatively longer distances, they can sometimes go where e-buses cannot, and they have more room for passengers. Finally, modern trolleybuses do not put as high a demand on metals, as the overhead lines do not need replacing as often as batteries and the batteries required for trolleybuses are considerably smaller than what is needed for regular e-buses, and with the reasons stated above they are a potentially more environmentally responsible choice, at least right now.
Thank-you for reading to the end, and we look forward to writing for you again soon.