CHRIS MILLS. Powering electric vehicles with ‘‘Swap-n-go” power packs

May 8, 2019

In Australia, a minuscule 0.3% of vehicles have electric propulsion, notwithstanding that those acknowledging the reality of anthropometric Global Warming recognise that transportation is the largest emitter of greenhouse gases.  Possible reasons for resistance to electric vehicle purchase include high price, ‘range anxiety’ and long charging times. Those with an eye to the future might add the future cost of replacing batteries and the ‘fear of missing out’ (FOMO) of future technology developments that will increase battery capacity and hence vehicle range. This purchasing resistance could be overcome with an engineering and design initiative: ‘Swap-n-Go’ Standard Power-Packs for electric vehicles.

Difficult commercial problems are solved by innovative companies; liquefied natural gas bottles used in caravans and for barbeques being an example.  It takes about 20 minutes to fill a 4 Kg gas bottle and the fill must be attended; unacceptable if there is a queue of customers at a service station waiting for a fuel fill.  The Elgas Solution was to create a network of suppliers where a customer swaps an empty gas bottle for a full one – a transaction that takes seconds.  This is the model proposed for powering future electric vehicles.

Here is how the ‘Swap-n-Go’ system would work.  An electric vehicle, whether driven manually or by an Artificial Intelligence Agent, knows the remaining charge in the batteries and the location of battery swap stations along the planned route.  When its time to ‘re-power’ the vehicle, the navigation system drives to the Swap-n-Go station and pulls into a power-pack exchange bay. A robotic system removes the low-charge battery and replaces it with a fully charged one, a process that might take less than a minute and would be faster than a fill of petrol, diesel or gas.

To make thus system work, electric vehicle batteries would be standard, or at least one of a few standard sizes – much like the AA, A, C and D batteries with which we are all familiar.  This is another example of standardisation for the convenience of customers – imagine how frustrating it would be if every torch had an individually designed battery and you had to find a replacement when the battery was drained.

There have been claims that Electric Vehicles with crash the electricity transmission grid by overloading the network at peak times.  The opposite could be true as redesign could make the grid more stable and resilient.  Australia has about 6,400 Service Stations. A fully developed Swap-n-Go network might have about the same number of exchange stations distributed across the nation, soaking up renewable power when it is cheap, recharging the Swap-n-Go battery bank.  One useful feature of electricity it that is flows in both directions.  If the grid needs additional power, it could draw electricity from the massive storage in the Swap-n-Go battery bank network.  Think of the contribution of grid stabilisation and reduced power costs provided by the Tesla Mega-Battery in South Australia, expanded by orders of magnitude.

Additionally, ‘smart’ cars at home with inbuilt dual recharging (power-pack swap and plug-in) could store power from rooftop Solar PV or inexpensive off-peak electricity and provide power to the house during expensive peak-load hours. Households could choose an electric vehicle rather than a storage battery as part of the house energy management system. A smart, grid-connected car can reduce household energy bills.

There have been claims that revenue from fuel excise will be reduced by widespread use of electric vehicles.  This is an easy fix!  Repowering an electric vehicle in a Swap-n-Go station will be paid for, with the price being made up of these components: rent for the power-pack, cost of the kilowatt hours to fully charge the battery (credit would be given for the power remaining in the swapped battery), and a ‘power excise’ used to generate revenue for road construction and repair.  A truly smart car and smart battery could charge for the distance driven and the location of travel, equitably matching the power-excise with vehicle use.

Using the dry-cell analogy, different vehicles could use different but standard sizes.  A small city car might use an ‘AA’ battery, the family car an ‘A’, the Tradies Toyota Hilux a ‘C’ and trucks and busses a ‘D’.  Some vehicles might use several batteries to extend range and towing capacity.

Vehicles with fixed routes such as trams, trains and busses could have Swap-n-Go stations built into the route infrastructure.  With automated fast swaps, a bus could be recharged in the time it takes for passengers to egress and ingress.

An what of Diesel-Electric trains?  These might be converted by a battery-carriage that feeds the locomotive’s electric motors with power, bypassing the diesel-powered generator. Battery-carriages would be swapped and charged as an integral part of the railway management system.  The analogy is the tender or coal-car of steam trains.

Standardisation leads to efficient recycling.  When the Swap-n-Go station detects that the charge capacity drops to a nominated level (say 90% of new capacity), the power-pack would be sent to a recycle-renew centre.  The power-packs would be designed for easy disassembly, with components being reused.  The battery component would be separated into elements and be reused to make new batteries.  Currently there is some anxiety about the availability of cobalt which is an essential component of lithium batteries.  Reusing elements such as cobalt allows limited supply to catch up with expanding demand, reducing the cost of electric vehicle batteries.

Lithium batteries for electric vehicles are improving rapidly and improvements would be incorporated into the Swap-n-Go power-packs.  A person driving a Swap-n-Go electric vehicle might expect to be pleasantly surprised that their vehicle makes fewer stops for re-powering due to the increased capacity of newer technology batteries.

In summary, these are the benefits that a fully developed Swap-n-Go network powering electric vehicles would deliver:

  • Lower purchase cost electric vehicles, as the battery component would be rented;
  • Elimination of ‘range anxiety’;
  • Repowering times less than filling a vehicle with fossil fuels;
  • Stabilisation of the electricity transmission grid;
  • Reduction of power costs by replacing peak-load power with off-peak or renewable power;
  • Lower greenhouse gas emissions;
  • Avoidance of the capital cost of replacing battery packs that have lost charge capacity;
  • Recycling and reusing standard power-pack components to lower power-pack costs; and
  • Automatic incorporation of battery improvement technology developments into standard power-packs.

Chris Mills is a MSc in Systems Management and is a systems designer and builder.



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