Quarrying & Mining Magazine
Feature

 How green is my EV?

Alan Titchall looks at what goes into the making of electric powered vehicles.

As your electric vehicle (EV) runs on electricity, the source of that power determines how ‘green’ any electric vehicle is.

And, while 84 percent of generation in New Zealand is ‘renewable’, electricity worldwide is mostly (60 percent) generated by fossil fuels.

Which means most EV users around the world source fossil-generation to run their electric vehicle, so produce nearly as much CO2 per kilometre as a petrol or diesel vehicle.

Electric vehicle sales in New Zealand are just over one percent of total vehicle sales, with Kiwis preferring the far less expensive, and almost as-green-efficient, hybrid vehicles such as the ubiquitous Toyota Prius. While the Prius burns petrol when its batteries are not engaged, it produces roughly the same amount of greenhouse gas (200 grams per mile, according to data from the U.S. Department of Energy) as the all-electric Nissan Leaf.

How much coal did my EV burn in its making?

For the past 100 years cars have been constructed mostly of steel for both chassis and body. Mined iron ore is smelted in a furnace with heat generated from fuel coke derived from coal or petroleum.

The bulk of the emissions from making steel results from the industrial process where this coking coal is used to melt iron ore, and as a source of carbon to remove oxygen from that ore in a blast furnace in the making of steel.

As of 2020, steelmaking was estimated to be responsible for seven to nine percent of all direct greenhouse gas emissions worldwide. Making one ton of steel produces about 1.8 tons of carbon dioxide.

Mining around the world is essential for sourcing the coal, coking carbon, and iron ore.

The specific coal used to make coke is low-ash, low-sulphur bituminous coal, like the coal mined and exported from New Zealand for steel making around the world. A similar product called petroleum coke, or pet coke, is obtained from crude oil in oil refineries.

Oil and gas for plastics

All cars need a lot of plastic, both inside and out. Around 66 percent of the plastic used in an EV is polypropylene – for the likes of the bumpers, cable insulation and carpet fibres – while another 17 percent is polyurethane for foam seating, insulation panels, suspension bushings, cushions, electrical compounds, etc.

Plastics are made from raw materials like natural gas, oil or plants, which are refined into ethane and propane. Ethanand propane are then treated with heat in a process called “cracking” which turns them into ethylene and propylene. These materials are combined together to create different polymers.

EVs need tyres, of course

All cars need rubber tyres, which eventually wear out and have to be replaced – at least three times in the lifetime of a vehicle. To save battery power the tyres used on an EV must have as little resistance to road surfaces as possible. Even the steel/alloy wheel design on an EV can have a significant role in boosting efficiency. Car and Driver magazine found last year that just using Tesla’s ‘aero wheel covers’ on a Tesla Model 3 improved its efficiency by more than three percent, or about 10 miles of range.

Meantime, when EV tyres reach their use-by-date they end up with the same problem as all other end-of-life tyres (ELTs). And this is a major international environmental problem.

Tyrewise is an industry-led product stewardship set up years ago here to provide for the nationwide recovery and safe disposal of ELTs. The total volume of tyres (car, truck, aircraft etc.) which come to the end of their useful life in New Zealand each year is currently equivalent to over 7.75 million passenger tyre equivalents – some 73,700 tonnes worth. Tyrewise estimated at the time that it was set up that only 25 percent were recycled and the rest ended up in landfills, were illegally dumped, or stockpiled where they pose a fire-risk. The Tyrewise programme started in March 2012 with the Ministry of the Environment awarding Waste Minimisation Fund funding for the development of a stewardship programme. Since then it has been a long slog with two phases (not a lot happened under phase one) with reports and government department and key-stakeholder discussions over the decade-long idea of ‘mandatory stewardship’. As far as I can tell, Tyrewise and the country is still waiting for the government’s decision on tyres to be declared ‘priority’ waste products.

Special fossil fuel oils

Your EV has an engine of course and with very fast moving parts spinning wheels on axles that need special lubrications.

While these fluids don’t need to be changed regularly, as they would with a combustion engine (and no fuel combustion to degrade the oils the way it does in regular petrol and diesel engines), as hybrids and EVs become increasingly powerful and their battery ranges and charging speeds improve, standard fluids are unable to keep up in terms of robustness, heat resistance and cooling capacity.

Electric vehicle engines experience big fluctuations in power flows and high motor speeds of up to 15,000 revolutions a minute. They can require several oils – for the gear reducer, which is the EV’s transmission, and an oil specifically for the electric motor for cooling. Lubricants exposed to high voltages and temperatures require very specific dielectric properties to protect key components such as coils from corrosion and abrasion while preventing electrical short circuits. The vehicle’s lifetime and safety depend on it.

Lubricant producers are also watching the introduction of the electric dual clutch transmission, or eDCT. This is a multiple-speed automatic gearbox for EVs that draws on the example of the DCT. The eDCT uses an e-motor in addition to the twin clutch for seamless shifting. Because of the electrical components and wiring involved, the gearbox fluid has to provide copper corrosion protection while being compatible with the insulation and other unique materials of this gear box. And the word ‘copper’ brings us to minerals and mining.

How many mined minerals in my EV?

Mined materials such as copper and lithium are key materials for all EVs. The high electrical conductivity makes copper the main critical component used for electrical wiring (around 80kg in an average EV), windings and organs.

Copper mining wastes make up the largest percentage of metal mining and processing wastes generated in the United States. The largest copper mine is found in Utah (Bingham Canyon). Other major mines are found in Arizona, Michigan, New Mexico and Montana. In South America, Chile, the world’s largest producer, and Peru are both major producers of copper.

A peer-reviewed study of the track record of water quality impacts from copper sulfide mines found severe impacts to drinking water aquifers, contamination of farmland, contamination and loss of fish and wildlife and their habitat, and risks to public health.

Lithium, the Holy Grail material for EV battery producers is mostly sourced from hard rock mines in Australia, or underground brine reservoirs below the surface of dried lake beds in Chile and Argentina. Some 56 percent of the total resource mined is used in batteries.

The largest environmental danger posed by lithium mining is the amount of water the process uses – an estimated 500,000 gallons of water per ton of lithium extracted. This can endanger the communities where the lithium is being mined because it can cause droughts or famine if operations are not kept in check.

Meanwhile, the global market for alkali metal lithium is growing rapidly. Between 2008 and 2018 alone, annual production in the major producing countries rose from 25,400 to 85,000 tons. Although also used in the batteries of laptops and cell phones, and in the glass and ceramics industry, an important growth driver is its use in the batteries of electric vehicles.

So, how green is your EV? As green as you want it to be.

 

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