This post is a part of my CLIMATE CONUNDRUM Series. See all posts in this series here - Aircraft and battery size - India Renewable Energy Consulting – Solar, Biomass, Wind, Cleantech
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Aircraft and battery size

For all the talk about electric aviation, the industry is yet to figure out how to overcome a fairly hard problem – let’s call it the 40:1 problem

Batteries – even the best of them – have energy densities of only about 300 Wh per Kg. The energy density of aviation fuel is about 12000 Wh/Kg, about 40 times that of batteries.

A 200 ton (empty weight) Boeing 747 today carries around 120 tons of fuel for a long distance flight (though it has a capacity of about 200 tons). I have not been able to get precise estimates for fuel to useful energy efficiencies but I reckon it should be in the 30-35% range as we are talking gas turbines for large aircraft. Electric motors are far more efficient, about 85%. If I consider all the above, if that long haul Boeing were to run fully on batteries at 300 Wh/Kg, it needs to carry about 2000 tons of batteries.

It will never fly – figuratively and in this case, literally!

Is it possible for battery energy densities to increase significantly?

I’m not the expert here, but I have not seen any company envision higher than 600 Wh/Kg – that would still mean 1000 tons of batteries – no fly!

It appears that battery propelled aircraft are destined for smal aircraft, short haul routes for the foreseeable future.

See my LinkedIn post on this topic

About Narasimhan Santhanam (Narsi)

Narsi, a Director at EAI, Co-founded one of India's first climate tech consulting firm in 2008.

Since then, he has assisted over 250 Indian and International firms, across many climate tech domain Solar, Bio-energy, Green hydrogen, E-Mobility, Green Chemicals.

Narsi works closely with senior and top management corporates and helps then devise strategy and go-to-market plans to benefit from the fast growing Indian Climate tech market.


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