Our article looks at the way in which technology and policy is being implemented to help drive the next global auto-revolution.
Range and rapidity of charge are two of the crucial challenges faced by electric vehicle ('EV') users currently. Over the last few years, battery technology has evolved rapidly. However, matching the range and convenience of traditionally refuelled vehicles has been an uphill task for manufacturers. EV manufacturers are teaming with specialist cell-technology providers to create batteries that are both energy-dense, as well as capable of rapidly charging. The other area of development is enhancing the acceleration of EVs, and that is spurring the development of super-capacitors that increase the charge capacity and the performance of the EV.
The obvious leader in EV battery technology is Tesla. It is experimenting with producing batteries with cathode made of lithium-iron-phosphate. These batteries will be free from cobalt, which is expensive to obtain, and is often mined and procured unethically (nearly 50% of the world production of cobalt comes from the Democratic republic of Congo, a war-torn region). These batteries will have higher charge as well as discharge rates, even though they will not have a high energy density. To offset the disadvantage, Tesla is in the process of redesigning its battery shell to a prism shape, from the current cylindrical shape. This will enable the company to pack in more batteries in any given space to increase the energy to space ratio.
At the same time, increasing energy density within an EV battery has been a major target for all manufacturers globally. A high energy density battery will hold a higher level of charge, thereby enabling an EV to travel further, essentially increasing the range that the EV can travel without having to recharge. Redesigning battery packaging to make efficient use to available space is one way of increasing the net energy availability for a vehicle. Increasing the energy density of a cell by incorporating more efficient cell structures and materials is another.
Energy density in lithium ion batteries have nearly tripled during the last decade, and recent developments are set to increase this further. Canadian utility provider Hydro-Quebec is currently engaged in the development of a solid state battery with a glass electrolyte. The race is to create batteries with solid, non-flamable electrolytes. Meanwhile, Samsung Advanced Institute of Technology is experimenting with micro silver-carbon layer to reduce anode thickness and boost energy density to 900 Wh/L. This will enable the cell to maintain a very high energy density, and also increase the number of times a battery can be charged well beyond the typical 1000 cycles common in lithium-ion cells today. Among the challenges of metal based solid state batteries is the propensity of the metal layers to grow dendrites – microscopic metal whiskers – that can short-circuit the cells and reduce its lifespan. This technology, currently in the developmental phase, will enable EVs to have an enhanced range of up to 800 km. South Korean researchers are also experimenting with replacing the graphite anode with a silicon anode, resulting in accelerated charging times.
However, the global availability of lithium is concentrated in South America (Chile and Bolivia) accounting for nearly 65% of total reserves. With China controlling most of the lithium mines in these areas, non-lithium based technologies are rapidly finding favour with countries that do not want to be dependent on Chinese lithium exports. This is pushing development into carbon-based technologies to develop batteries that can have a rapid-charge mechanism, and as well as have a longer lifespan. While most lithium batteries are rated to 1000-1500 cycles, if a battery is not completely discharged, then the charge cycle counts increase. Experiments conducted on Lithium ion batteries show that they lose only about 25% of their capacity across 300,000 kms of driving. This is a significant advantage that carbon-based batteries will have to approach. This is particularly important since the battery cost can account for between 40%-50% of the cost of an EV. For two-wheeler EVs this percentage can be as high as 70%.
Rapid developments in battery technology is set to increase energy density in cells, as well as charging convenience. This will enable EVs to travel further, and charge faster – no more overnight charging would be required. However, the energy stored in the cells would need to be generated elsewhere before they are placed in the cell. Some environmentalists argue that in developing countries (viz. India) where electricity generation continues to be predominantly coal-based, EVs merely shift the point of pollution from the vehicle to the thermal power plants spewing smoke and associated pollutants. In India almost 72% of the coal produced is used in thermal power plants to generate electricity. Almost 74.5% of the electricity generated in India is from coal alone. With greater electricity required to power a growing number of EVs, and their high density cells, pollution from power generation will be a significant concern in the near future.
Globally, there have been significant deliberations and developments in discovering effective and efficient means of harnessing renewable sources of energy to generate electricity. Harnessing solar power has been a popular, if expensive, option that has seen significant adoption globally. Cheap silicon-based solar cells have flooded the markets, spurring several countries to impose anti-dumping duties to save domestic manufacturers. However, cost of the panels is a small part. The land on which solar panels must be placed, and the corresponding batteries that will store the energy are significantly more expensive. Later in this article we have discussed how recent developments in solar panel technology is allowing for greater harvesting of solar energy, which can in turn address the environmental concerns around use of EVs.
Providing adequate charging facilities for EVs is another concern. Sutherland Avenue in London was recently renamed as Electric Avenue after 24 lamp-posts on the street were converted by Siemens to charge electric vehicles. Lamp-posts provide already existing infrastructure for EV charging. Owners can plug in their vehicles and leave them overnight, and are billed for the energy they draw on the basis of an attached meter. While cities contemplate converting their streets to enable EV charging, they might want to consider environment friendly ways of generating electricity and move away from coal-based generation for EV charging. One solution to the problem of environmentally friendly power generation, again, is photo-voltaic cells.
Other means of charging EVs include charging stations that are set up especially to charge EVs, as well as battery-swapping schemes. Under the battery-swapping schemes – as commonly seen in the e-rickshaw segment in India and elsewhere – EV batteries are energised and provided to drivers by third parties who charge for their services. Using battery-swapping, drivers of EVs can almost instantly re-energise their vehicle by dismounting a depleted battery, and mounting a freshly charged battery unit. However, this is possible largely with e-rickshaws that are operated widely in the Indian sub-continent. Most of the e-rickshaws in India operate on a 1000W motor that is powered by standard lead-acid 12V battery which takes about 10 hours for a full charge. Battery-swapping is made easier because the battery unit requirement is standardised across all e-rickshaws operating in the country.
With rapid development of battery technology for cars, and particularly with each manufacturer utilising their own proprietary battery packs, EV battery swapping is still some way away. In the future, we can hope to see global industry bodies coming together to ensure battery compatibility across EVs to ensure greater choice for consumers, as well as easier swapping options. One might recall the days when each brand of mobile phone came with their proprietary charging units, and the wires were not compatible. That changed with the development of the Micro-USB charging ports (though Apple remained defiant). However Type-C charging units are now creating even greater compatibility among personal electronic devices as far as charging their batteries is concerned. We should hope to see similar compatibilities in the future for EV battery technology as well. This would include standardisation of power requirements for EVs, as well as of the mounting racks where batteries are to be mounted on them.
With the prospect of roadside lamp-posts being converted to dual use EV charging platforms, one way of reducing the carbon footprint for EV charging is to further convert these posts so as to be powered by photo voltaic cells. Lamp posts with photo voltaic cells have been around since the last few years. However, the challenge is to (i) generate adequate energy to power EVs, and (ii) to store the energy internally. The latter can be addressed by devising high energy density cells in-built into the posts. The former has seen several developments in the recent pasts, most of which have been linked to capturing a larger number of photons on the solar cell surface. Part of the development has focussed on specialised pigments that are able to harness the energy of the sun more efficiently, often by reducing the amount of photons lost due to reflection from the cell surface.
One of the fastest growing solar cell technologies today is the Perovskite Solar cell. These are lead or tin halide based solar cells, and these replacing silicon cells that are currently in use. Tin halides (lead being a poisonous compound is less favoured) are gaining favour as they are also cheap to produce and implement. Perovskite cells have enhanced solar energy conversion rates by as much as 29% over previous generations of silicon-based cells.
Another branch of developing solar technology is the pigments used in capturing the photons on the cell. Carbon nano-tube technology is the new frontier that is being developed at several research institutes. Vantablack, perhaps the most famous of the super-black pigments for its association with artist Aneesh Kapoor, is developed with a low-temperature carbon nanotube growth process, and can absorb 99.96% of all light thrown at it. However, researchers at the Massachusetts Institute of Technology are working on bettering future super-black pigments to be ten time more efficient than Vantablack. Carbon nano-technology tubes are also able to absorb lights at wider angles, meaning that solar light can be turned to electrical energy for longer durations of the day more efficiently. This, in turn will, enable solar cells attached to lamp-posts to gather a greater quantum of energy throughout the day to energise EV charging systems.
In addition to solar cells affixed to EV charging facilities, large-scale solar power projects can also help in reducing the dependency on fossil fuel-based electricity generation, thereby creating a net positive green energy utilisation to power EVs. Land and battery costs are significant deterrents to implementing solar power projects. At the same time, India has seen significant investment in large solar PV projects. Cost of setting up solar PV projects in India has dropped 80% between 2010 and 2018. This has been achieved through aggressive targets and streamlined efforts made by the government towards implementation of solar policies. Competitive tariff-based bidding has reduced the cost of solar power from INR 17 per unit in 2010 to a low of INR 2.44 per unit in 2019. Public awareness campaigns have also greatly accelerated adoption of solar power in the country. Certain state governments have also been providing open access to solar projects through concessional wheeling and banking facilities for solar projects. Additionally, availability of subsidies and incentives under the Jawarharlal Nehru National Solar mission, and tax incentives viz. Accelerated Depreciation Benefit (between years 2010 and 2015) have also massively spurred the development of solar projects across states. The government had also provided 30% subsidies for rooftop solar installations, previously. In addition to monetary benefits, the government has also accelerated the identification of large tracts of land for large-scale solar power installation, and has prioritised the use of government wastelands and non-agricultural lands for solar installations. This is expected to speed up the process of land acquisition to enable faster implementation of solar power projects.
Looking into the near future, a combination of high energy density battery cells, new age cathode technology, and advancements in photo-voltaic cells, as well as larger green energy power projects will render EVs to become better positioned to render efficient, convenient transportation with very little degrading effect on the global environment.
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