Lancaster, Calif.
Len Engel
Executive Director
Antelope Valley Transit Authority
In 2016, the Antelope Valley Transit Authority Board of Directors set a goal of becoming the nation’s first fully battery-electric bus fleet by the end of 2018, with plans to convert all of the authority's diesel buses to a 100% battery electric fleet. Effective energy management has been a key component to the success of their conversion project. AVTA has developed a system that uses both high-power wireless inductive chargers and 89 hard-wired conductive overnight charging stations to help power their zero-emission buses. Inductive charging allows the electric buses to charge wirelessly en route using charging pads embedded into the ground. The 250 kWh inductive charging stations haves the potential to add up to 20 miles of range tofor an electric bus for every 10 minutes of charge time., supplementing their 89-stall conductive over-night charging stations at the AVTA facility in Lancaster . The agency currently has two operational inductive charging stations, with plans for up to 11 more in the region.
AVTA worked with Southern California Edison (SCE) to gain an understanding of how much energy they could consume at their facility. Through this process, it was determined that SCE could only provide about half of the power needed to satisfy their long term plan. To compensate for the lack of available power, AVTA worked closely with I.O. Controls, who had already created on-board health monitoring software (HAMS), to create the Electric Load Management System (ELMS) to manage peak charging requirements and take advantage of lower evening rates. A charging schedule was developed and implemented to optimize efficiency and reduce consumption by staggering charging and activating “float” modes to avoid unnecessary energy consumption. Prior to implementing the ELMS, AVTA studied energy rates so they could program the system to take advantage of off-peak hours. In addition to taking advantage of off-peak hours, slower conductive charging is the most cost effective method due to the fact that SCE implements a demand delivery charge based on the highest 15 minutes of consumption.
Another important aspect of designing a sustainable electric bus program is accommodating for growth. AVTA considered not only their short term needs during planning and development stages, but factored in their 5, 10, and 20 year growth plans to minimize costly expenditures associated with system expansion. During the planning phase, AVTA studied the different chargers offered by various manufacturers to capture knowledge on the technology and properties of 480V 3 phase charging supply. Additionally, they installed a 1.5 megawatt backup generator, which can power the entire charging infrastructure in case of an emergency.
Pilot programs are a valuable tool for collecting data that can be used for planning charging infrastructure and determining. Test chargers mileage ranges, while accounting for environmental factors such as heat or grades. Electric fleet conversions cannot be executed under a one-size-fits-all model, consideration must be given to the distinctive qualities of each project. In looking at the bigger picture, pre-planning goes a long in saving money and improving efficiency.
St. Cloud, Minn.
David Warren
Director, Sustainable Transportation
New Flyer
Battery-electric transit buses are being deployed in cities at an increasing pace. Transit agencies are focusing on pilot programs to learn best practices on battery sizing and charging strategies. The goal is to determine the how to specify an electric bus as a one-for-one replacement with a diesel, compressed natural gas (CNG) or hybrid bus. Transit agencies are considering two types of configurations for these pilots: 1) Long-range bus, 2) Quick-charge bus. Both types have unique charging and battery strategies to consider.
A long-range bus carries a relatively large energy storage system so the bus can operate for extended periods of time on a single charge. For distinguishing purposes, a long-range bus travels a minimum of 125 miles or nine hours in continuous service on a single charge. A long-range bus may have a minimum of 300 kilowatt hour (kWh) of batteries, and may typically consume up to 30 kWh of energy per hour in mild-weather conditions. Long-range buses are charged using a plug-in depot charger and would typically be charged once midday, and then again overnight in preparation for morning service. Typical charging times in this scenario would range from 3.0-4.5 hours per session. During a 24-hour day, a long-range bus may spend a total of 16 hours on-route, and eight hours plugged into a depot charger.
A quick-charge battery-electric bus carries a smaller energy storage system, about 150 kWh of batteries. Quick-charge buses are charged multiple times during the day using a high-power on-route charger (up to 450 kW). A quick-charge bus is capable of operating up to four hours, and/or 50 miles without recharge. Approximately six minutes of charge time is needed for every hour of service for a quick-charge bus. During a 24-hour day, the quick-charge bus can operate around-the-clock without needing a plug-in charge.
So which is better — a long-range bus or a quick-charge bus? It depends. Some considerations include:
- Avoid excessive demand charges (the capacity to utilize high power at any given time). Time-of-use utility charges can be costly. Transit agencies should meet with their power company early to fully understand the power rate schedules.
- Minimize demand costs by ensuring high utilization of each and every charger, regardless of charger type (plug-in or on-route charger).
- Placing on-route quick-chargers in a city can be complex and expensive. Involve city and utility stakeholders early in the planning process.
- Power from the grid to bus depot may require costly service upgrades that should be forecasted early in the planning process (Example: a 50 bus plug-in fleet may require up to six megawatts of continuous power while charging overnight).
- Long-range buses have battery packs that weigh up to 6,500 pounds. Gross vehicle and axle weight rating limitations may reduce passenger capacity. Conduct this analysis before committing to a long-range or quick-charge bus strategy.
New Flyer foresees both types of electric buses, and perhaps a blend of these two, as a vital part of the complete transit solution. Both types are best — when planned properly.
San Francisco, Calif.
John Haley
Director of Transit
San Francisco Municipal Transportation Agency
We are excited about the possibility that by 2025 we will be able to provide an all-electric fleet that won’t require overhead wires. This is why we have tried to be forward thinkers and will continue to take steps to test electric vehicles here in San Francisco. However, while the technology is emerging rapidly, it isn’t quite ready for primetime. Bus manufacturers aren’t yet producing the number of all-electric buses San Francisco and other urban areas would need, nor could we guarantee that the vehicles would work for the required 15 years with heavy ridership and challenging topography. We would also have to consider new facilities that can charge a large fleet and developing a systemwide infrastructure to charge vehicles in service. This type of planning and development could take several years.
Anyone familiar with San Francisco and Muni service can tell you that we have the largest electric bus fleet in the United States (more than 250) in our electric trolley buses, which carry our heaviest loads on some of our most demanding routes. We've been a pioneer in the electric vehicle industry for years and we plan to continue that trend. In fact, over 50 percent of the transit fleet, including light rail, cable cars, historic streetcars and electric trolley buses are largely powered by greenhouse gas free hydropower. Beyond that, our new electric hybrid buses use 100 percent renewable fuel which is developed from low carbon intensity feedstock sources. This eliminates greenhouse gas emissions and petroleum fuel and saves a million gallons of fuel each year. This year, we plan to start a pilot that would run electric hybrid buses on battery power for a significant portion of the route and charging them on the remainder of the line, while they are using the renewable fuel. We feel this will give us a better sense of how the current technology can accommodate today’s service needs. On top of that, when the technology is ready, we can upgrade the current hybrid engines to full battery power.
Muni's transit system is the cornerstone of our city's environmentally sustainable transportation system and is one of the greenest in the world. We believe the national focus shouldn't simply be on how fast can we move to all-electric buses, it should be on making transit service even better so even more people ride it. This is why we are working so hard to put new and cleaner vehicles into service, because at the end of the day, attracting more people to transit will have the greatest impact on reducing greenhouse gas emissions.
Brisbane, Australia
Dr. Paul Sernia
Chief Product Officer and Founder
Tritium
Terminology
- EV - electric vehicle
- Fast charger – typically offers up to a 50kW charge
- Ultra-fast charger – can offer a range of ultra-fast charge speeds from 150kW-475kW
- User unit – the unit that has a cable and plug which delivers the charger into the vehicle
Key considerations for fleet owners or operators when planning for the effective and efficient running of their e-fleets in future is of course, the planning. If a fleet is transitioning to electric vehicles then the planning needs to focus on the future, not the ‘here and now’. What will your fleet look like in 12, 24 or 36 months’ time? What will it look like when the fleet is 100 percent electric?
Ultimately the objective is to match the charging infrastructure to the needs of the fleet, and plan any investments to occur when they are needed. Most businesses will be in a position where they can’t fork out millions of dollars upfront to build the ultimate charging system.
The hardware of EV charging is a major requirement to look at, but there are also some serious electricity supply needs that must be factored into planning. The questions for which answers are required include:
- What sort of supply is needed?
- What can be delivered now with the existing supply infrastructure?
- When will I have to look at upgrading?
- What will be the impact on the cost of our fleet?
When planning for electrification of a fleet, there may be just as much to look at on the electricity supply side than on the infrastructure side.
Fleet operators should also consider the behavior of their vehicles and what time of day the charging may need to take place? Are chargers needed en-route, or will there be a back-to-base system, or maybe a hybrid of the two?
In the early stages of e-fleet transition operators have a perfect opportunity to support or advocate for public charging stations in their areas of operation. A fleet owner could theoretically transition to an e-fleet and not need a major onsite infrastructure investment at all. If they have sufficient public DC charging stations available to them, they can plan to use these. A Typical 50kW DC public charger can fill an EV battery in 20-30 minutes.
The above may also offer fleet operators the chance to negotiate with the owners of local public charging stations — both on access to the sites (no parking fees for example) and lower rates of charge for being a ‘frequent charger’, especially if the charging can take place at off peak times.
From a technology perspective, when the time comes for the fleet owner to invest in their own charging infrastructure they need to consider a system that can grow and adapt as their needs change. Such adaptation would consider developments in charging speeds, capacity of vehicle batteries, advancements in vehicle design.
Tritium has developed an ultra-fast charging system that enables fleet owners to invest in ultra-fast charging (up to 475kW) with a small initial hardware outlay, which can be built on over time. Such a system needs to be:
- Scalable – the charging infrastructure can be adapted and updated to keep pace with developments in vehicle technology. Eg: currently most vehicles can only take relatively low power charges, say 50kW. Within the next few years vehicles will be able to take much higher power charges and the infrastructure must be able to deliver this.
- Flexible – the ability to offer a variety of charging options across your infrastructure, depending on vehicle needs. For example, if you have a fleet that comes back to base at night for a full overnight charge, you may want a system of slower, low power chargers. If your fleet is on call and runs 24/7 you may need ultra-fast chargers that can fill a battery in less than 5 minutes.
- Intelligent – technology architecture that self manages power demands and allocations depending on how many vehicles are charging at the same time.
- Customizable – the ability to have a system that is optimized for the site and business needs; now and into the future.
Fleet operators need to consider that their infrastructure set up will be around a lot longer than a typical fleet vehicle so the long-term vision, focusing on flexible and scalable solutions is critical if transitioning to e-fleets is to be effective.
