In Part II of the EV technology feature Graham Brennan looks at the likely pathway to more cost-effective EVs and the infrastructural requirements as well as the possible opportunities for Ireland in developing the solutions needed to manage the dynamic electrical loads
Elec

 

Author: Graham Brennan, transport programme manager SEAI

This is the second part of a discussion on Electric Vehicles (EVs). The article attempts to deal with all of the main arguments put up against the adoption of the EV by the motoring world. In Part 1 the key issues of emissions, efficiency, range and battery life were dealt with. Part 2 continues the discussion and looks at the likely pathway to more cost-effective EVs and the infrastructural requirements. The possible opportunities for Ireland in developing the solutions needed to manage the dynamic electrical loads implied by the emergence of a large number of EVs on Irish roads are also considered.

Capital cost


EV-battery5

Nissan Leaf 24kWh battery pack configuration (192 cells in 48 modules producing 360V)

Car companies must recover the cost of any R&D investment in new technology through the price of the vehicle. As the volume of production rises and engineers find faster and cheaper ways to make the product, the unit price begins to fall. These effects can be seen at present in the EV market.

In 2011 there were only two EVs available to the Irish consumer, namely the Nissan Leaf and the Mitsubishi iMiEV. Initially offered with a driving range of 170km, the Leaf was by far the more popular model and had an unsubsidised price of €40k. By the middle of 2013 the vehicle was updated with a range of 200km using the same 24kWh battery pack (see Fig. 1).

The unsubsidised price was €30k for the basic model, which represented a €10k reduction in capital cost within a 2.5 year period. The combined subsidy currently offered is a maximum of €10k, resulting in an on-the-road price of about €20k for the Leaf, which is now competitive with many vehicles in that class. This reduction was possible because instead of shipping each car from Japan, Nissan opened a factory line in Sunderland and also found ways to cut costs and time from the production process for the battery pack and vehicle.

The strategy of the Obama administration in the USA has been to provide investment in battery R&D and manufacturing facilities in order to bring battery performance up while reducing costs. Similarly, France and Germany have provided substantial investments to their automotive companies in order to reduce the investment costs for their companies which, in turn, should result in EVs entering the market with lower capital costs for consumers.

Through these investments combined with the rapid growth and potential scale of the lithium battery market (both for EVs and electricity grid storage applications), it is estimated that battery manufacturing costs have already reduced from €900/kWh in 2009 to €300/kWh today and are predicted to reach €150/kWh by 2020.

Workers check production of lithium-ion automotive batteries in Johnson Controls Saft Advanced Power Solutions' factory in Nersac

Graphite being ‘printed’ onto a copper conductor sheet to form an anode. Similarly, the cathode material is printed onto an aluminium sheet and a separator layer is rolled out to separate the two electrodes. The three sheets are sandwiched together, cut, sealed in a pouch and finally filled with electrolyte

Figure 2 presents an image of a graphite anode being ‘printed’ onto a copper conductor plate. A similar process is used to print the cathode onto an aluminium plate. A third roll containing the separator material is fed between the two electrode sheets.

The battery is sandwiched together, cut, sealed, filled with electrolyte and placed into a stack. While the final selection of chemicals will continue to evolve, the basic mechanical structure and manufacturing process of the battery cells seems to be consolidating.

Operating costs


Taking the example earlier of the Leaf and Auris, we see that the EV has an efficiency of 150 Wh/km and the combustion vehicle has an efficiency of 380 Wh/km for the same standard drive cycle. Putting these together with the unit prices for electricity and diesel, we find that the energy cost for an EV is 1.34 cents/km and that of the diesel vehicle is 4.9 cents/km resulting in a typical energy cost saving of 70 per cent.

It is worth mentioning that the current price of oil is hovering around $50/bbl, which is a far cry from the $100/bbl price of summer 2014 and will impact on the financial savings argument offered by the EV. It is, however, considered that this oil price is being held artificially low by the OPEC countries.

In terms of maintenance, as there are no spark plugs, exhausts, oil filters and various widgets which only your mechanic will claim to understand, the maintenance interval for an all-battery EV could be expected to be longer, thus reducing the lifetime service costs.

Infrastructure


When charging, a battery must be supplied with DC electricity at its terminals. At home, the standard AC single phase 230V supply is used, which is then rectified and converted by the on-board charger into DC electricity for the battery. This allows a 24kWh battery to be charged in about eight hours from a 3.6kW domestic circuit. On-street chargers also supply AC electricity to the car at 230V but are wired with three phase supply.

This enables 22kW of charging power to be supplied, allowing the car to be charged in about 1.5 hours. ESB has deployed 820 (note generally there are two chargers on one post) of these public chargers throughout Ireland’s towns and cities.

Getting more power than this into the battery involves stepping up the voltage and current. To handle this increased power, the car would typically need another on-board charger, which would be even heavier than the existing one and add more cost. Therefore, the charger is moved off-board onto the charging station itself.

These fast chargers can deliver 50kW (at 400V) of DC power directly to the batteries and can require a separate plug to that used for home or street charging. Fast chargers can charge a 24kWh battery to 80 per cent capacity in 20 minutes. With such high current moving through the battery cells, heating becomes an issue with implications for battery life as discussed in Part 1. Battery cooling strategies may be employed to combat this.

There are two standards of DC fast charging currently available. First, there is the Japanese standard Chademo and, second, there is the new standard favoured by European manufacturers called the Combined Charging System (CCS). The CCS standard allows a single common plug socket to be fitted to the car which will fit both the domestic AC plug and the CCS fast charge plug. All plugs contain signal pins which make the connection live only when the socket is plugged into an EV. The pins also communicate with the charger to select what level of current is required by the vehicle.

Finally, yet other manufacturers choose to supply high power AC directly to the AC motor in the car and run it like a generator to create DC electricity to charge the batteries. This system has the advantage or reducing the cost of the fast charging infrastructure with what is claimed to be a modest increase in vehicle price.

As manufacturers hedge for position and the technology and power requirements continue to evolve, it is difficult to get world agreement on fast charge standards. ESB under its Pilot EV Infrastructure programme is examining each technology and, to date, has installed 69 Fast Chargers at petrol stations at approximate intervals of 60km between urban centres. Some of these chargers provide all three fast charge methods for trial purposes and may need to remain that way until a single preferred option emerges from the manufacturers (see Fig. 3).

EV-battery7

A Fast Charge Station with three different standards under trial: Chademo, CCS and AC (ESB Ecars)

The normal demand profile for electricity is a sinusoidal curve showing a trough at night and a hill during the day time. By filling in the night-time valley, the electricity assets are used more efficiently and daytime prices can be reduced. Fig. 4 shows an example of a future electrical demand profile in Ireland over a single 24-hour period in winter time.

evf

Potential impact of 250,000 EVs on a future winter supply of electricity scenario (Eirgrid)

Also shown is the expected impact of 250,000 EVs using charging patterns with load -controlled charging. Due to the high energy efficiency of the EV, the impact on the night valley appears modest and manageable. This suggests that the EV roll-out will have modest implications for transmission system development. Presently there are two million passenger vehicles in Ireland, so the penetration rate of EVs has a long way to go before significant transmission system investments will be required to support a majority share EV market.

Smart grid opportunity


As the average battery size rises from 24kWh to 100kWh, the demand for power at domestic and public charge points will increase. The maximum power an Irish home could supply is 14.7kW. If we allowed half of this to be used for EV charging, then a 100kWh battery would take 17 hours to charge allowing for AC/DC conversion efficiencies in the charger.

Similarly, as more and more EVs appear on Irish roads, the combined effect of these becomes a concern. The network operator would have a difficult job to balance the power system if a million EVs were suddenly plugged in at 6pm when workers return home.

Therefore, a method of managing these loads intelligently on a future ‘smart grid’ will be required. This offers an opportunity to develop methods and tools to allow the aggregation of this distributed energy storage and to collectively purchase electricity to match peaks in wind or ocean generation.

Making vehicles ready and available to absorb intermittent renewable energy may be enhanced by the use of induction or plug-free charging. In this case the driver simply centres the car over an AC induction plate built into the drive way which enables contactless charging.

As discussed in Part 1, it is likely that EVs will have ample battery life available to meet the expectations of the average motorist. It is also likely that the battery will have sufficient life to store and supply electricity for other purposes. For instance the car could purchase low cost night rate or renewable electricity and provide this for use in the daytime. The vehicle could also sell reserve power back to the electricity network and receive payment for this service.

Conclusions


EVs offer greater energy efficiency and emission reductions than the best combustion vehicles in the market today. Manufacturers are now committed to the EV and are making substantial capital investments worldwide, with 11 models now available in Ireland.

EU regulations and labelling on vehicle CO2 have been a success across Europe; however, the particulate emissions have risen significantly in response. This is likely to turn the tables further in favour of EVs if wider pollution taxes for passenger vehicles are considered. Emissions Trading is already in place in the electricity industry and will be used to reduce average emissions from Europe’s electricity sector by 80 per cent by 2050 with respect to 1990.

In Ireland today there are 850 EVs on the road with demand for cars in 2015 rising by a factor of three with respect to 2014 sales. EV battery range and life are improving steadily, with the prospect of an affordable 600km range vehicle by 2020 looking possible.

Somewhere along this development path a vehicle will emerge that will allow the Irish motorist to drive across the country consistently with a single stop. Given our mild climate, island geography and excellent renewable energy resources, the EV will meet the requirements for the Irish consumer sooner than they will for larger countries with more extreme seasonal changes. With its exceptional energy cost savings, the EV is therefore poised to one day become the vehicle of choice for the Irish motorist.

http://www.engineersjournal.ie/wp-content/uploads/2015/06/EVnew1.jpghttp://www.engineersjournal.ie/wp-content/uploads/2015/06/EVnew1-300x300.jpgDavid O'RiordanElecbatteries,electric vehicles
  Author: Graham Brennan, transport programme manager SEAI This is the second part of a discussion on Electric Vehicles (EVs). The article attempts to deal with all of the main arguments put up against the adoption of the EV by the motoring world. In Part 1 the key issues of emissions,...