Welcome back to Switched On, a series of articles that we are writing to help operators to understand the best ways to drive down the lifetime costs of electric coach and bus operation.
In our first couple of articles, we set out the key drivers of total cost of ownership (TCO) and then focused on battery degradation. In this month’s, we look at depot design and how to match that to the needs of electric vehicle (EV) fleets today – and tomorrow.
Depot electrification presents a unique set of challenges that, when approached in the right way, can minimise TCO.
This article sets out how and why, based on our experience of supporting over 650 EV chargers and 1,000 battery-electric vehicles to date and our repurposing of end-of-life EV batteries.
As ever, if you have any questions, please get in touch.
Steven Meersman, Co-Founder and Director, Zenobe.
How to build an electric depot and keep costs down
For coach and bus operators, electrification means not only replacing the vehicle’s fuel tank with an electric battery, but also replacing now obsolete fuel pumps with charging infrastructure.
That represents an exciting shift in the way public transport operates, but in practice it means a fundamental rethink of depot design. Charging infrastructure is a new principle for operators that can be daunting if best practice is not followed.
Start by thinking long-term
When considering how to design, build, and ultimately successfully operate a fully electrified depot, it is important to consider both current requirements and future expansion. That requires a holistic approach that considers TCO within the charger infrastructure design process, rather than thinking purely about upfront cost.
A fully thought-out planning process will minimise unnecessary future costs – known as regret costs. In some cases, diesel depots are not ideally designed to accommodate charging infrastructure. Planning for 100% electrification involves reassessing existing parking plans, reviewing the location of bus washes, and evaluating vehicle running lanes.
That will not only have an impact on the total available parking bays but can also affect peak power requirements depending on whether the vehicles park in a first vehicle in, first vehicle out strategy, or a last in, first out approach.
When planning depot designs, consideration of the following three pillars is key to avoiding regret costs:
- Planning for the future
- Power distribution
- Optimisation.
We will investigate these in more detail in the following sections.
Planning for the future
Before commencing electrification work on any given site, comprehensive planning should be carried out by the management team to ensure that all future scenarios for an electric fleet’s requirements are allowed for in the depot plan.
Once the operator’s strategy is understood, surveys will be undertaken to understand depot operations. Consideration needs to be given to parking, the bus wash, and vehicle running lanes – as detailed above.
Undertaking topographical surveys ensures that accurate working drawings can be produced, and vehicle schedules can be assessed to determine peak power requirements. New plans showing 100% electrification can then be produced, identifying installation phases and aligning them to the business’s electrification strategy.
A major cost and time risk with a project is installing a new electricity connection into a site or upgrading an existing connection. Distribution Network Operators (DNOs) have been challenged by Ofgem to utilise their networks 24 hours per day, which presents a good opportunity for bus operators to access power through a timed connection.
Alternatively, they could explore a ramped connection that increases in capacity over a period. That allows for a phased approach to obtaining additional capacity, thus reducing initial costs and avoiding excessive upgrade expense.
Given the increasing demand on the electricity network and the high costs of installing a new connection, future planning for capacity becomes an incredibly important strategy.
What is more, depending on the depot’s load (the amount of energy required to charge vehicles), the location of the on-site point of supply and the configuration of any on-site private high voltage network (if required) can have a huge impact on both upfront costs and the ability to easily introduce more EVs in the future.
Sizing key electrical components such as substations and low voltage switchboards to accommodate the full potential electrical load of a depot is also essential. When compared to designing for single phases of electrification, this approach prevents the risk of needing to upsize these components later. Furthermore, low voltage switchboards may be extensible, avoiding upfront costs but allowing for future expansion.
Power distribution
Depending on site layout, installing a private high voltage network may be the most cost-effective solution to distribute power. If designed correctly, it can provide a greater level of resilience by reducing the risk of a single point of failure.
Moreover, covering a large distance with high voltage aluminium cabling is significantly more cost-effective than installing low voltage cabling. This principle is key to keeping TCO of electric coach and bus fleets as low as possible, and the Zenobē team always design sites with this in mind.
Location matters, too. High voltage and low voltage equipment should be in close proximity to the highest concentration of chargers. That is due to low voltage cabling contributing a significant proportion of project costs.
Siting low voltage switchboards close to the chargers as well as correctly sizing cables will also reduce kWh losses over the lifetime of the chargers, further reducing excess cost through energy bills.
Optimisation
As mentioned, the operational requirements of bus fleets are a critical consideration when designing electric depots and garages.
Without a fundamental understanding of the requirements of routes running from each depot, it is almost impossible to design an optimised electric operating centre. That means it is imperative to consider future route requirements in the design stage, as they will impact the hardware required and the depot layout.
There are a wide range of charging solutions on the market, whether they are AC or DC standalone chargers or DC space-saving solutions such as dispensers, pantographs or drop-down cable reels that are mounted to a ceiling structure.
Space-saving solutions do help to solve a problem, but they also come at a premium when compared to a standalone charger. Both standalone units and space-saving solutions will require additional space when installed. Analysis needs to be carried out to see if the benefit of the space saved warrants the additional cost when compared to safety and vehicle requirements within the depot.
Specialist electrification providers like Zenobē will be able to support by walking operators through different charging solutions with the various charger manufacturers. Each has its own unique set of benefits that might enhance your depot design and help to save costs.
As well as the location of the chargers within the depot, the type of charging facility (i.e. AC vs DC, standalone vs space-saving), and the supporting software, are key considerations for driving down TCO.
These will be determined by the route requirements and the power available at the depot. For example, route schedules that allow for longer charging windows will be able to be supported by slow charging, which will limit battery degradation.
Undertaking analysis of vehicle schedules and determining the peak power required to charge the electric fleet is only one part of the charging optimisation process. Reviewing, assessing and modelling against energy tariffs is the second.
Many depots can be contracted to a dual- or multi-band energy tariff where it is more cost-effective to use energy between certain hours of the day or night. Installing a larger electricity supply means that charging sessions can be condensed into a shorter time window throughout the night, taking full advantage of the cheaper tariff.
The key to benefiting from this is upfront analysis during the design stage and the implementation of smart charging software to monitor and manage that once the depot is live.
Futureproof your depot to save costs and headaches in future
In summary, identifying and avoiding potential regret costs should be a key focus for coach and bus operators throughout the infrastructure design process. Electrification specialists such as Zenobē can help to manage this by ensuring that all futureproofing considerations are included in any design.
Exploring methods of bringing power to the site, comparing cost options with DNOs and independent DNOs, and considering on-site battery storage in the design are all possible avenues to drive down build costs.
In the next article in this series, we will take a look at what happens when you are ready to go live, and some of the key considerations for you and your depot teams.
Got a question? Feel free to get in touch with us through our website.
