Electric motor, Lithium batteries and the environment

Is an electric motor and its batteries more polluting than a diesel motor as some people claim ?

First of all, what kind of pollution are we talking about ?

  1. Concerning air pollution* (fine particles): Electric engines of a boat do not emit any fine particles contrary to a Diesel or gasoline motor and in particular those boats on which there is no or which rarely have an antipollution system.
    *According to the World Health Organization, it is responsible for more than 8 million deaths per year in the world (more than tabacco and even 15 times more than wars)
  2. Concerning CO² emissions, responsible for global warming: there is a time factor and an energy mix factor that come into play too (where do we get the energy to manufacture, fill and recycle these batteries?)

Environmental impact of batteries manufacturing

A lot of energy is needed to manufacture batteries and unfortunately the countries that produce batteries have very polluting mixes (China for example) and we also have to take into account the transport. It is considered that 150 KG of CO² are needed for 1 KWH of batteries.
If we take the case of a battery pack with 15 KWH for a 40 feet boat, the negative balance of CO2 during the delivery will be – 2250 Kgs of CO².

Conclusion: At the delivery of a battery pack, the balance is negative for electricity.

Environmental impact of using batteries for a boat

During use, the impact of recharging the batteries depends on the energy mix of the electricity supplier. If we connect to the quay of a French port, you will have a very good result since our electricity is mostly nuclear.
In other cases, such as a boat equipped with flexible or rigid solar panels and hydro generation to recharge its batteries. We can consider that the Co2 emissions will be almost non existent (Contrary to the way electric cars work)
We arrive at the most important factor which is the durability of these batteries.
One liter of diesel emits 2,67 KG of CO². So we make up for the initial deficit after having saved 850 liters of diesel. (2250/2.37) assuming that a boat consumes 3 liters per hour, that gives us around 300 hours.
From 300 hours (12.5 days) of charge of batteries, the results for electric power are therefore positive.

Knowing that a lithium battery will last more than 10 years or 4000 cycles, we can make a fast calculation: With a 40 feet boat that consumes 5 kW at 5 kts, 4000 cycles X 15 KWH/5KW = 12 000 hours of motor.

The results at the end of the first life of batteries are therefore already very favorable for electricity.

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End of life of the battery and its recycling

First of all, it should be noted that a Lithium battery is not completely unusable after 4000 cycles. It will have lost 20% of its capacity and could therefore be used for the storage of wind or photovoltaic energy. The concept is already in use at Renault and Tesla for example.

At the end of this 2nd life, recycling Lithium batteries does not pose any particular direct pollution problems, because the elements used (lithium, iron, phosphate) are products which are found in nature and are not dangerous unlike lead-acid batteries.
Lithium is 95% recyclable. On the other hand, energy is necessary to recycle it and this is deducted from its positive impact.

Finally, there is no doubt that an electric boat has a largely positive impact on reducing C0² emissions.

Other elements to be taken into account :

  • Odor pollution: Electric motors does not emit any odor
  • Sound pollution: electric motors are not noisy
  • Oil and diesel spills in the water: Here again, an electric motor is a good ecological choice…

Lithium and rare earths resources

Rare earths

Contrary to what is going around mainly on social networks, lithium batteries do not contain rare earths, (lithium is a metal).
Rare earths which are often exploited in shameful conditions, are used most of all to refine oil and to fabricate catalytic converters! They are found in small quantities in electric motors but not in batteries.


Lithium can still be found in important quantities in the world (This is less true for cobalt)
A lithium battery only contains 1% lithium, which means 300 grams for 1kWh.
Lithium is 95% recyclable.

Contrary to what is claimed, China does not monopolize lithium.
In these conditions, it seems that it’s shortage is not around the corner,
Of course, if 100% of cars go electric, there will be some tension, but on the one hand we are not there yet and on the other hand there are already alternative lithium technologies in the laboratory.

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