Are Electric Vehicles really good for the environment ?

Manoj Manduva
Jul 19, 2019 · 11 min read

When vegetarians and non-vegetarians argue, it usually ends in the statement “plants also have life and feelings”. I haven’t seen this argument to have a plausible ending.

And when people argue if Battery Electric Vehicles (BEVs) are really clean and sustainable or considered to be one of the solution for air pollution ?

I think there is an ending, even though it is complex. I will try to get there.

Well ‘good’, is a relative term and we need something for comparison and in this post, I will be comparing the Electric Vehicles (EVs) with traditional vehicles also known as Internal Combustion Vehicle ( ICEs ).

There are many types of Electric Vehicles. The ones which run on both fuel and electricity of those which can be charged or cannot be charged. Of all, you hear a lot about the ones which run only on electricity and can be charged. They are called Battery Electric Vehicles ( BEVs) or Plug-in Electric Vehicles ( PEVs ).

The main argument I hear is that “the electrical energy used by the BEVs is still coming from traditional coal burning plants and doesn’t reduce any CO2 or CO emissions, but just displaces it from the roads polluted by ICEs to other areas where the electricity is generated. So the net pollution and green house effects remain the same”

Well I have an answer here.

No matter how the electricity is produced in the current scenario, BEVs are more cleaner than the traditional ICE ( Internal Combustion Engine) vehicles.

To get to this conclusion may be by the end we will have simple answers like

How much energy goes as waste to travel 1 KM in both the ICE and BEV vehicles?

How much CO2 is emitted into the environment to travel 1 KM by both ICE and BEV?

Before going into the analysis, we need to understand how efficiency of cars is being measured?

It is called as

Well to Wheel Efficiency

It is a framework to measure the efficiencies of the various steps involved in providing the fuel necessary for the vehicles to run on the road.

Well to Wheel = Well to Tank + Tank to Wheel

There are two factors that we need to consider while really getting into a conclusion.

Energy Efficiency and Emission Factors.

Efficiency factor is all about how much energy is being efficiently utilised at each step without wastage relative to the output we get.

The ‘emission factor’ is what determines how much of Green House Gases (GHG) or other pollutants are being emitted at each of these steps.

So in short, we have a table of comparisons for ICE and BEV across efficiencies and emissions.

First let us see the Well to Tank component.

Well to Tank

As the name suggests it is the journey of the fuel from origin to the vehicle’s tank.There are different pathways for each kind of fuel whether it is Gasoline or Electricity used to run the vehicles.

For Gasoline pathway

The pathway is from the oil’s source, drilling, transportation, refining, distribution to pumps across the country. Similarly each kind of fuel has a different pathway and for simplicity sake, let us consider gasoline for comparison.

There is an efficiency and emission factor at each of these steps.

Gasoline Pathway

They depend a lot on where the crude oil is produced, from where is it sourced, how much distance it travels to reach the refinery, the number of products that are produced at the refinery.

In fact, refining crude oil consume a lot of electricity that too from some of the coal burning plants.

The energy utilised during refinery process is distributed across the many sub-products like Hydrogen, LPG, pharmaceuticals etc produced along with Gasoline or Diesel, which makes it fairly efficient process of upto 80–90%.

Roughly 4 to 6KWh is required per gallon of gasoline. With that energy you could drive 20 Miles on an electric car says Elon Musk. So it doesn’t make sense to produce gasoline and drive around. However, it is debatable.

Oil Refinery at Night ( Image Source : Futurity.org )

Oil refineries have high emission factor. The Volatile Organic Compounds ( VOCs ) along with NOx, SOx etc are high. The carbon dioxide emissions during oil production and processing were estimated to be 130 kg CO2 per Ton of Oil Equivalent. For each ton of hydrocarbon production, there would be release of 1 kg of methane, and 0.4 kg of nitrogen oxides. ( Read from the source & source )

It gets difficult to follow the NOx and SOx emissions along these pathways due to overwhelming data. So for now let us ignore these emissions from our equations. :(

By considering the Miles per Gallon equivalent ( 1 gallon of gasoline delivers 33.7KWh with which we can drive roughly 100miles conservatively) and converting the CO2 emissions per kilo-meter we would get around 7g per KM.

Coming to Transportation and Distribution.

Assuming the oil is sourced from Middle East countries, the ships have to travel on average 6000 KM. They are considered to be one of the most polluting vehicles on the planet. It is said that 16 ships produce same amount of pollutants as all the cars combined in the world. According to this post, the world’s largest container ship travels 28 feet on a gallon of residual fuel oil (149,690 BTU or 1.2 gallons of gas). This equals 0.001 KM Per Liter !!!

Huge Oil Container Ship ( image source : British Petroleum)

Getting the fuel from refinery to every part of country involves railways, road transport.

By considering the CO2 emission for each mode of transport per litre of gasoline and then converting it to per kilo-meter driven it would be around 3gm per KM.


So in total it would be around 10grams of CO2 per KM while bringing the gasoline from well to tank with 85% energy efficiency of refining process.


All the other factors of production, transportation and distribution make the pathway for Gasoline: average in efficiency and high in emissions.

When we talk about BEVs , the mix of sources to produce electricity varies by country. In United States, Natural Gas is the main fuel used whereas in India it is Coal. For each pathway there will be different efficiency and emission factor. For simplicity sake let us consider Coal. We will also consider the electricity produced by clean energy sources like solar and wind.

So we have two pathways here for calculating Well to Tank efficiencies.

For Electricity produced from Coal Plants

As of today 30–40% of electric energy produced is from coal burning thermal plants. They are one of dirtiest ways of producing electricity. Unfortunately in India, it is around 55% of all the electric energy produced and contributes around 70% of all the GHG emissions.

Energy Mix — Electric Energy Sources in India as of 2018

Even electricity produced from burning natural gas is better than coal because the excess heat produced is used again to produce steam and eventually produce some more electricity.

Coal Based Thermal Plant Pathway

Heat Rate determines the efficiency of Thermal Power Plants. It is the amount of heat energy required in Kilocalories (from burning fuel) to produce one Kilowatt-hour of electricity in a power plant is called the heat rate of the power plant. The lesser the heat rate, the more efficient is the plant.

The efficiency of most of the Coal based thermal power plants are 38–45%. Also, there are power distribution losses by the time it reaches our homes.

coal fired electricity generation plant (image: snowbrain.com)

This makes the Electricity pathway from Thermal Power Plants very inefficient in the order of 30%.

It is not good with respect to emissions either. It has been found that 0.8–0.9 kg/kW h CO2 is emitted in Indian power plants.

So for every 1KWh of the energy used by the BEV unfortunately 55% is coming from these inefficient power plants.


It is roughly around 130g of CO2/ KM which is way to higher compared to the Gasoline pathway. If the country’s entire energy is produced by Coal based power plants, then it will be 266 g of CO2 /KM with around 30% energy efficiency.


But it doesn’t end here.
A lot changes with the Tank to Wheel analysis.

For Electricity from Solar or Wind sources

Ugh..! Now we can breathe freely.

Even though the photovoltaic cells cannot capture the entire energy falling onto them they would not emit any Green House Gases.

4 out of world’ largest solar parks are being built in India, which is a good sign.

The other advantage of photovoltaic parks is that, it can scale to provide energy to grid or be minimal for the need of independent use cases like vehicle charging stations.

2,000 megawatts (MW) park, named Shakti Sthala (power spot) spans across 13,000 acres in Karnataka, India.
Solar Electric Pathway

The efficiency of most of the Solar Power Plants is around 35%.

There are some side effects of offshore wind turbines, causing imbalances in the ecology of the marine life, displacing dolphins and sharks to farther areas.

Also the wind turbines cause obstruction to the migratory birds flying in the direction.


For Electricity produced by renewable source, the emission are 0g of CO2 per KM with around 35% Energy Efficiency for Well to Tank.


Tank to Wheel

The efficiency in using the energy from burning the fuel in the tank to run the engine and eventually move the wheels on the road.

ICE vs BEV

Well, in Battery Electric Vehicles ( BEVs ) there is no tank but a big battery storing the energy. We can consider how the stored energy is being spent to move the wheels.

The number of moving parts in a BEV is less, around 30+compared to an ICE where there are at least 30,000 moving parts.

Most of the moving parts of a traditional ICE vehicle are replaced with battery, power electronics and an electric motor ( called as the Electric Drive Train ).

The motor sits in between the wheels and transmission of power is direct and lossless. Since there are less moving parts and less energy losses, the Tank to Wheel efficiency of BEVs is high. Considering the efficiency of AC to DC conversion, battery storage, AC induction motor efficiencies it is around 70–75%.

Where as in ICE the Tank to Wheel is around 16%. The engine’s efficiency is just 28%. It seems they are better heating machines than drive engines. Considering the losses with drive shaft it is further less and comes down to 16%

So BEVs score a lot in energy efficiency.


BEVs are 75% energy efficient

whereas ICEs are just 16% efficient.


Emissions

Now let us consider the emissions during Tank to Wheel.

The main advantage of BEVs considering emission is they don’t emit at all. So it is Zero Emissions.

A diesel ICE car emits around 130g of CO2 / KM. The number is higher for bigger vehicles like trucks. Surprisingly Petrol cars produce way more higher ,160g of CO2/ KM.

However, petrol cars produce fewer pollutants and fine particles. Both petrol and diesel cars are equally bad over lifetime.

So BEVs are a no brainer with regards to emissions.


BEVs have Zero emissions

ICEs emit 160g of CO2 per KM.


In conclusion, if we put all the numbers together and add the ‘well to tank’ and ‘tank to wheel’ efficiencies and emissions, we have 3 Pathways and an extra case where all the electric energy is coming from just coal based thermal plants. So let us see how it is.


The Well to Wheel for ICE ( Gasoline pathway ) = 10 g of CO2 /KM ( Well to Tank ) + 160 g of CO2 / KM ( Tank to Wheel )

170 g of CO2 /KM at 40% Energy Efficiency

For an Internal Combustion Engine Vehicle ( ICE ) on an Gasoline Pathway

The Well to Wheel for BEV ( Only Thermal Power Plant Pathway ) = 260 g of CO2 / KM + 0g / KM ( Tank to Wheel )

260 g of CO2 / KM at 40% Energy Efficiency

For a Battery Electric Vehicle (BEV) on 100% Coal based Electric Energy Pathway

The Well to Wheel for BEV ( In General Mix of Electricity Pathway) = 130 g of CO2 / KM + 0g / KM ( Tank to Wheel )

130 g of CO2 / KM at 40% Energy Efficiency

For a Battery Electric Vehicle (BEV) on General Energy Mix Electricity Pathway

The Well to Wheel for BEV ( Only Solar or Wind Generation Pathway ) = 0 g of CO2 / KM (Well to Tank + Tank to Wheel )

0g of CO2 / KM at 50% Energy Efficiency

For a Battery Electric Vehicle (BEV) on an 100% Clean Energy Source Pathway

If coal is the only source of Electricity , then EVs are no better. In fact they are worse compared to all other vehicles. So. the short answer to the question,

“Are Electric Vehicles really good for the environment?” is

Well, it depends on the energy mix ( from which source the electricity is produced and in what ratio )

But in India and mostly anywhere on the Planet EVs are far better and cleaner than any of the ICE, because the energy mix of any nation is not completely from coal burning thermal plants.

So along with increase in EV adoption so is the necessity to increase Clean Energy Production. Only this path will help us reduce emissions and put the planet on the green run.

However, EVs will effectively reduce the NOx SOx PPM2.5 pollutants on the roads and enable us cleaner cities to breathe.


End teaser :)

There are varieties of EVs

BEV — Battery Electric vehicles or Plug-in Electric Vehicles ( Tesla like cars )

PHEV — Plugin Hybrid Electric Vehicles ( Prius like cars, which can be charged and can also run on gasoline )

HEV — Hybrid Electric Vehicles ( Can run on both Electricity and Fuel but cannot be charged )

FCEV — Fuel Cell Electric Vehicles ( Which run on Hydrogen Fuel )

Who is the most efficient of the above all?

FCEV.

There are some challenges for the adoption of FCEV , may be in the next post.

Thank you.

Thanks to Nandini and Naveen Rabelli for reviewing the article.

References :

https://www.ecta.com/resources/Documents/Best%20Practices%20Guidelines/guideline_for_measuring_and_managing_co2.pdf

https://www.greenbiz.com/article/designing-tesla-building

https://www.hydrogen.energy.gov/pdfs/13005_well_to_wheels_ghg_oil_ldvs.pdf

https://www.sciencedirect.com/science/article/pii/S0196890405001214

https://www.scientificamerican.com/article/earth-talk-the-coal-truth/?redirect=1

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