Keep em’ rollin’: EVs battery technology and power
In Part 2 of his look at electric vehicle opportunities for the electrotechnology industry Peter Vandenheuvel touches on battery technology, power distribution and related aspects.
The electric vehicle rollout requires two battery categories, as the battery construction for electric traction is quite different to that for stationary energy storage, which may be used as a stationary back-up electric vehicle (EV) supply.
Onboard batteries will be designed and supplied by EV manufacturers with third-party after-market replacements most likely following shortly after.
Battery energy storage systems will be specified, or selected, by charging stations or commercial and domestic users. For stationary support of EVs at least three main uses have been identified:
- as a home or charging station ‘back up tank’;
- to obviate the need for upgrading the premises’ incoming supply; and,
- for commercial energy trading operation, possibly combined with a PV setup.
It should also be noted that many battery manufacturers recommend charging batteries to only 90-95% of their capacity to optimise service life.
(Further, there are considerable losses in charging a battery, perhaps more than 10%. An EV may use 20kWh per 100km travelled, but the loss from wall outlet to battery and then battery to wheels could be 20% of Metered power. These losses will double if stationary storage is also used.)
There are many battery types – at least 12 different lithium batteries alone. Each group has its own chemistries and hazards. A detailed matrix is published by AI Group and others.
Hazards arise from almost every battery related activity. The Standard AS/NZS 5139 Safety of battery systems for use with power conversion equipment is being drafted and it is likely to be referenced in AS/NZS 3000 as either a normative (mandated) or informative document.
Of critical importance are the hazards to people and property from electric shock, arcing, arcing fault, fire, explosion (gas, liquid or solids), spillage, contamination, poisoning, disposal, etc. These hazards make an extensive risk analysis essential for each type used, as the consequences can be catastrophic by way of injury or death from electrocution, arc flare or shock wave injury, or destruction of property from a blast or fire.
Remember: connected in series the voltage hazard increases; if in parallel the current hazard increases.
The stationary battery market penetration is presently only about 3% or 20,000 units. It is expected to be 17% by 2030, and in 10 more years it may grow to 2,000,000 units.
One important issue is the perception battery manufacture is prone to high levels of pollution during the manufacturing and disposal cycles.
Areas of increased business for the electrotechnology industry include:
- installation of the expected ten-fold growth in battery systems;
- becoming a stationary battery ‘go to’ installation designer and supplier (possibly with a ‘cradle to grave’ service);
- understanding and advising on losses during charging and discharging;
- advising on battery hazards and safe work methods on batteries;
- development and/or promotion of low-pollution batteries;
- optimising battery life or extending the life of stationary battery banks, including by selective cell replacement or ‘rejuvenation’;
- determining viability, design and installation of battery banks for energy trading (buying energy cheap and selling when expensive) as a stand-alone business or as part of an EV charging station installation;
- finding and training individuals as experts in the selection, use, installation, and hazard management in handling, maintenance and disposal; and,
- reducing battery costs and/or increasing battery capacity.
There are about 6,400 conventional service stations across Australia. If the uptake of EVs is to succeed, the charging network must off er the same convenience as ‘petrol servos’, and run in parallel.
As EVs will spend longer at the charging point and make more visits, there will need to be a similar number of charging bays to petrol bowsers. The typical servo has eight bays, therefore more than 50,000 in total. Even with some rationalisation and charging at other places, some 3,000-plus EV charging stations with 25,000 bays will be needed.
That means there will be high capacity charging stations with multiple connection points in many suburbs, towns and at regional fuel stops. A typical mid-size, fast-charge station will use as much power as 750 to 1,000 homes with incoming supplies up to a 1,500A three-phase 1MW supply for a 12-bay station.
Infrastructure Australia is proposing a national rollout of fast-charging sites as one of its most pressing investment priorities over the next 15 years. This must also include some major upgrading to electrical distribution systems. If the 1986 to 1996 change from leaded to unleaded petrol is any guide, that took 11 years and was much less disruptive and less involved. So it is not unreasonable that an EV rollout could take 15-20 years.
Interested enterprises would therefore be well advised to get on board early, finding and working with developers that build the charging stations.
As a result, electrical contractors will be needed to:
- install the electrics for 3,000 charging stations with potentially 25,000-plus charging bays, along with 3,000 or so related convenience stores and fast-food outlets;
- develop a modular ‘one size fits all’ charging station design that can preferably be stand-alone or at least paired in back-to-back configurations and to Australian and New Zealand Standards;
- develop ways of safely accommodating petrol and charging facilities at the same site;
- develop a ‘one size fits all’ (or most) connection plug and socket;
- develop or repurpose a customer point of sale metering and pay system;
- do the follow-up maintenance, vandalism repairs and revenue meter calibration;
- develop or implement a mobile charging breakdown service; and,
- establish a ‘one stop shop’ for all of the above.
There will be at least two essential power distribution upgrade undertakings.
The obvious one – how to supply 3,000-plus larger charging stations that will draw a new or extra load ranging from (say) 250kW to 1,000kW (or more) directly from the grid. The less obvious one: the vast number of lesser upgrade works for existing customers who want to have charging facilities, as this will also have a substantial effect on installed infrastructure. This will add more – but smaller – load demand upgrades overall but at many different locations.
This group includes, but may not be limited to, the industrial, commercial, car parking and similar organisations
that want to be involved in providing small to mid-size charging stations for their own or public use. It also takes in enterprises that want to provide substantial EV charging facilities free or ‘pay as you go’ for employees and customers, and for attracting new customers.
This will mean digging up lots of roads and footpaths, and upgrading and installing more ground and pole mounted distribution transformers and substations.
There are 19 million motor vehicles in Australia with 75% (14+ million being passenger vehicles), travelling on average 14,000km a year. Assuming EV market penetration will reach 75%, this will mean about 30,000GWh added to the grid load by that time.
According to the National Electricity Market, Australia used about 195TWh (195,000GWh) of electricity in 2017-
2018. With 75% of the passenger fleet as EVs this would mean a minimum additional load of around 15% on the grid.
These figures are rough estimates, but the undeniable conclusion is that substantial augmentation works and extra generation capacity will be required.
All this will come at a time when the electricity network will already be challenged, as there are other potential increases in electricity use to be catered for. They include the:
- continued rollout of kerb-side electrics for the 5G network;
- seemingly unlimited growth in data centres; and,
- charging points for people-shuttle drones and delivery drones predicted by futurists.
There is also ever-increasing complexity in the energy flow throughout the distribution network, with all manner of co-generation feeds coming into the grid from all over the place.
With these different sources, the energy flow pattern has changed quite drastically. It is no longer just a downstream flow from large power stations to cities and towns; it is now like a spider’s web.
This will need complex and sophisticated protection if we are to avoid state-wide blackouts.
Electrical contractors will be able to pick up additional business by:
- adding and upgrading substations, street and/or pole-mounted transformers;
- switching, installing and upgrading overhead and underground high-voltage and low-voltage lines;
- upgrading network protection, civil site-works and related activities;
- designing and/or installing stationary battery systems;
- improving demand management and load shedding;
- upgrading power lines and customer in-feeds (consumer mains) for many of the enterprises that want to provide charging stations – such as shopping centres, manufacturing plants, supermarkets and DIY chains; and,
- building or upgrading generation plant, substations, etc.
Return of the auto electrician
Tesla advertises EV battery voltages >300V DC, and other information states that voltages on vehicles are now 600V
DC or more.
There is further anecdotal information that mining industry EVs could be in the >1,000V DC range, and maybe even 3,000V DC. This imminent widespread battery use will expose many more people to battery, battery charging and charging set-up arrangement hazards.
People will be working on stationary support systems and batteries as well as on EVs. This will create the need for a range of specialist electrical technicians with new ‘smart’ skills – not only doing the work but safely managing potentially catastrophic hazards.
The voltages and currents involved are capable of extreme electric shock, arc-flash, arc-burn, shock-wave, explosion, fire and other major hazards, making these considerations crucial:
- Australian states and territories generally limit all work on voltages above ELV to suitably qualified people. So all workers, including technicians in EV manufacturing and dealerships, will probably need to be licensed.
- There will be many situations in which chargers and other gear will be aftermarket, repurposed, ‘one size
fits all’ or substituted. There will also be stranded EV situations – when the ‘any port in a storm’ rule is applied to avoid long waits for a technician or expensive towing – that will require someone more easily available to do
Setting the license issue aside, all employers have a legal responsibility to provide a safe and healthy place of work. In order to comply, they will have to ensure that employees are trained and accredited to recognised standards.
Areas of increased business for the electrotechnology industry and electrical contractors include:
- Companies or individuals entering this specialist area for installation, service and breakdown work associated with EVs (cradle to grave servicing).
- Training organisations developing courses in what will become a large, highly technical and skilled niche of the electrotechnology market.
- Regional businesses creating a high level of differentiation from competitors by gaining the necessary skills and the ability to safely provide competent EV support away from the big cities or after hours in the cities.
Converting the converted
There is anecdotal information on typical DC EV charging supply configurations, such as from solar or other DC feed-in systems.
The PV system installation practice is generally to convert the PV supply using a DC-AC inverter to feed into the AC grid-connected supply of the facilities. The AC supply is then used for charging and EV or stationary battery through
the AC to DC converter in the EV charger.
This circuitous route is probably as good as it can get on smaller systems, but there are considerable losses in charging a battery and more in using the energy in it.
Some publications suggest about 10% at each stage. This means 20% of the energy is lost between DC source and the charge in the battery. Then a further 20% if a storage battery is connected in between the AC installation and the EV charger. Hence for a larger system, with a substantial DC supply available, it would make sense to have a DC to DC direct connection if the voltages or interfaces are (or can be made) compatible.
Areas of increased business for the electrotechnology industry include:
- developing and selling or installing a simple low-loss system or inverter/converter that can take the output from a DC source and (in parallel or bypass switch-mode if needed) directly feed this into the DC side of the EV charger in a compatible way.
- developing batteries and converters with lower losses.