Interview – Statkraft and the Future of Renewable Energy
Richard Mardon, Head of UK Development at Statkraft, Mer’s parent...
The vehicles most of us drive today are powered by an internal combustion engine – which create energy by burning petrol or diesel.
Electric vehicles (EVs) however, generate electrical energy from a pack of batteries, connected to the electrical motor(s). At the moment the battery packs in EVs are made from lithium-ion – similar to those found in laptops and phones, but much larger and consist of hundreds of individual lithium-ion cells working together. Lithium-ion is the element of choice as it’s quick to charge, stores energy efficiently and can cope with thousands of charging cycles while still holding its charge.
When the accelerator is activated, the vehicle powers the motor, which gradually uses the energy stores in the batteries. When EVs are charging, the electricity makes chemical changes within the batteries. While driving, these changes are reversed to create electricity.
EV motors can also operate as generators – seen most effectively when a driver applies the brakes. When acceleration is stopped, the vehicle slows down by converting the forward motion back into electricity, and while braking, it recovers the thermal energy from the brake pads and tyre’s heat friction, storing it within the battery for future use – in-turn improving the car’s range. This is known as regenerative braking.
The unit of power for electricity is Kilowatt’s (kW), and kWh is a unit of energy, showing how much energy has been used. A high kWh means a high range.
Today’s EVs tend to be able to cover between 150-300 miles on fully charged batteries – a more than suitable distance for casual drivers and long commuters.
The battery size, and therefore range, varies from model to model. For example an EV at the cheaper end of the market with a smaller 40kWh battery might be able to reach up to 150 miles, but a more expensive Tesla with a large 100kWh battery could potentially take you up to 375 miles. Manufacturers are continually looking at ways to increase range – so expect to see improvements here in the near future.
Given that the average trip length in the UK is 6.8 miles and average trip time is 23.3 mins (Carwow) – most drivers shouldn’t be too concerned about the range achievable with an EV. According to Carwow data, the average electric car in the UK can travel up to 200.23 miles on a single charge, which means you could make over 8 trips before needing to recharge, and even drive as far as London to Leeds.
The average expected battery life for an electric vehicle is said to be at least a decade, possibly even double this, and it’s highly likely your battery will outlast the car itself (source). And rest assured, when the battery does need to be changed, it’s unlikely to be due to complete failure and instead will have just lost the ability to hold a full charge over time.
EV batteries are ‘buffered’ – which does mean that the car can’t actually use the full power stored in the battery. But this action reduces the number of charging cycles a battery needs to go through and the spare capacity also compensates for degradation over time.
In fact, to reassure those who may have concerns around longevity, all EVs on sale today come with long warranties, guaranteeing 70% capacity for up to 7-8 years of use. For example the BMW i3, Hyundai Kona Electric, Jaguar i-Pace and Nissan Leaf are all guaranteed for eight years/100,000 miles.
There are two considerations when it comes to managing your EV’s battery – getting the most of your day-to-day range and maintaining its long-term state of health.
Geotab’s battery health research found that it’s ideal to only charge up to 80% day-to-day. That being said, it’s fine to fully charge when you have a long journey ahead. And when you know you’re not going to use your car for a few days, try to ensure the battery is neither empty or full (ideally keep it within the safe range of 20-80%).
A recent study from GEOTAB revealed that exposing your EV battery to really hot temperatures will leave it prone to a noticeably faster rate of decline, compared to those driven in moderate climates.
GEOTAB’s study also found a notable impact from constant rapid charging. It found that level 2 charging is the best option for most charging needs and that rapidly charging a battery at high currents results in high temperatures – both of which have been shown to put strain on batteries.
Pre-purchase, be aware that certain car models have batteries that won’t hold up as well as others. This is sometimes down to battery chemistry and thermal management of the battery pack. The 2015 Tesla Model S for example, has a liquid cooling system, which degrades slower than a 2015 Nissan LEAF which uses a passive air-cooling system.
Certain factors will impact the amount of range you can get out of your battery. Being aware and adjusting your driving style and behaviours can reward you with more mileage:
Taking advantage of Regenerative Braking, functionality all EVs are equipped with, allows a vehicle to generate and store electricity from braking. Drive Electric suggests that drivers understand how to turn it on, up, and to fully take advantage of the feature by trying to slow the vehicle down sooner than needed by lifting off the throttle when approaching traffic lights etc. It should also be noted that aggressive braking is bad for range.
Temperature extremes, cold and hot, can adversely impact range. And so can the cabin temperature. Having the heating or air conditioning on uses the battery, and therefore decreases your range. In fact, Renault estimates extreme heating or cooling of your EV can reduce range by 30%.
To keep your car warm during the winter months, but not impact your range too much, drivers can always preheat the cabin while still plugged in (most models even allow you to control this via an app).
Driving at top speed (over 65 mph) tends to have the most detrimental effect on range and efficiency – due the increases in air pressure and rolling resistance.
On the other hand, the battery doesn’t have to work as hard when driving at slower speeds of around 30 mph. So taking slower stop-and-start journeys around town will allow you to get more range from your battery.
Therefore, if you’re running low on battery during a long journey – slowing down will help! For example, dropping your driving speed by 10mph can use up to 14% less energy.
Travelling uphill uses up battery power much faster than it would via flat terrain. Of course, you can’t always avoid a hill!
On the contrary, slowing down when going downhill will kick ‘Regenerative Braking’ into action – giving you additional range.
In the same way that aggressive braking is detrimental to range, aggressive acceleration on a regular basis can have a damaging effect. Instead, accelerating and driving smoother, in addition to utilising your vehicle’s ‘Eco’ or ‘Sport’ mode, will reward you more miles.
Naturally a heavier vehicle load will put more strain on your EV, reducing the range your battery will deliver before its next charge.
Last year, two British start-ups AMTE and Britishvolt announced plans to build the UK’s first large-scale EV battery factory, investing £4bn and focusing on lithium-ion battery production.
It’s clear why lithium-ion is the top choice for electric car usage – it’s efficient and charges at a fast rate. But there are many downsides – socially and economically. For example, lithium-ion battery production can result in toxic chemical leaks capable of destroying wildlife habitats.
As a result, there are trials taking place across the industry to find a better long-term solution.
One positive development with lithium-ion in recent years however is that costs have reduced. Back in 2015 the battery accounted for 50% of the cost of an electric vehicle, in 2019 it was around 33% of the cost, and looking at the cost today in comparison to 2010, the price of an average lithium-ion battery pack has dropped by over 80%.
A large societal issue with current lithium-ion batteries is the amount of Cobalt, a rare earth metal, used in their production – the majority of which is sourced from the Democratic Republic of Congo where it’s often mined by children in unregulated conditions. Manufacturers are now committing to reducing the use of Cobalt in the production process – or in Tesla’s case, removing it completely.
Researchers at the University of Texas are working on developing an EV battery that uses a high percentage of nickel (paired with manganese and aluminium) instead of Cobalt for the cathode.
Additionally, SVOLT, a company based in China, has confirmed the development of Cobalt free batteries for the EV market, claiming that they have a higher energy density, and could help EV ranges get up to 800km (500 miles), while also increasing the life and safety of the battery.
The hope is that silicon will gradually replace carbon as the anode material in lithium-ion batteries, as its capacity is ten times higher. However, silicon is currently facing big challenges due to its unstable material properties. Researchers at University of Eastern Finland have developed a method to produce a hybrid anode, using mesoporous silicon microparticles and carbon nanotubes – where the material is sustainably produced from barley husk ash.
US-based EV battery start-up QuantumScape has been making waves with their exploration of a solid-state automotive battery, which would remove a lot of the environmental dangers with existing lithium-ion batteries, and even make them lighter, cheaper and more efficient and enable a charge to 80% in less than 15 minutes.
Lithium-sulphur batteries are a way away yet – perhaps 2030 at the earliest, but the benefits could be great – they aren’t toxic, are 100% recyclable, cheap, and sulphur will replace the nickel, cobalt and manganese, saving up to 50% of the weight. Sony is said to have been working on it for years, with off-road vehicles and aeronautical applications likely to take advantage of these batteries first.
Lithium-sulphur also produces 40-50% more range, due to energy density.
NAWA Technologies has created an ‘Ultra Fast Carbon Electrode’ and intends to put it to use for electric vehicles by 2023. It is said to boost battery power ten-fold, increase energy storage by a factor of three and increase the lifecycle of a battery five times. NAWA believes a 1000km range could become standard, with charging times cut to 5 minutes to get to an 80% charge.
In the more distant future (perhaps up to 15 years from now) we may see the arisal of a compostable, organic lithium-oxygen battery. This ‘organic’ battery is described as graphene-based with a water-based electrolyte and said to be dense and capable of very fast charging.
Sodium-ion was developed at the same time as lithium-ion, and is coming back as a consideration for EVs as lithium prices are so high. It has slightly better extreme temperature performance.
CATL, a Chinese battery manufacturer which provides batteries to many car makers recently announced a new generation of sodium-ion batteries, with plans to improve energy density to about 200-Watt hours per kilogram, which is at least competitive with lithium-ion.
Research has been able to demonstrate a charging method that may make XFC – extreme fast charging a reality – delivering around 200 miles of range in 10 minutes with 400kW.
We already have many models claiming to offer a range of 250+ miles. And attempts to push the boundaries are already in progress, with Tesla looking to offer a range of 620 miles with their upcoming Roadster 2.
If Light Year One is anything to go by, we may start seeing more EVs with solar panel features, to allow for off-grid self-charging – which could further decrease costs.
Wireless charging infrastructure is also under exploration – involving charging ‘pads’ positioned underground – allowing for wireless charge-ups while parked. Trials have already begun, with the Department of Transport having installed wireless ‘pads’ in taxi ranks in Nottingham.
Batteries may be about to get cheaper, more efficient and faster to charge, but with the average range of electric vehicles increasing more power will be required.
We will therefore likely see a need for more rapid and ultra-rapid charging stations in convenient city locations.
Local authorities can help with the advancement of EV charging infrastructure.
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