You’re absolutely right in electric motors have greater thermal efficiency (85-90%) compared with internal combustion (30-40%). There are some additional important points.
First, even a 3-fold improvement in thermal efficiency still means an energy density disadvantage of about 30-fold. This means a gallon of diesel fuel at 7 lbs. would need to be replaced with roughly 210 lbs of batteries. A mid-sized powerboat carrying 300 gal of diesel (at 2100 lbs) would instead need about 63,000 lbs of batteries to have equivalent range – which obviously is impossible as it would be triple the total weight of the boat.
In a car 100 lbs of gas is replaced with roughly 3,000 lbs of batteries, which is doable, but much less so in an airplane where weight is critical to performance and range. There are battery powered planes already flying, but their duration is limited to about an hour in the air. That’s OK for short commuter hops, but not so much for longer distances (and also doesn’t leave much margin for bad weather or other delays). Such short distances may not have competitive advantages over trains.
Harbour Air in Vancouver is converting some of its classic De Havilland Beaver floatplanes to battery power, though flight time is limited to 30 minutes (with a 30 minute reserve):
https://www.flightglobal.com/airlin...le-electric-beaver-by-end-2023/148412.article
Water is more than 800 times denser than air. A boat moving through the water faces constant resistance. This is a primary reason a mid-size planning powerboat is lucky to get 1 mpg. There’s no ‘coasting’ or meaningful regenerative power available in a boat. The battery powered boats currently available, similarly to aircraft, have limited run times and ranges measured in mid-double digit miles. More if moving at below hull speed, less if planning. The limiting factor is battery weight and capacity.
https://www.soundingsonline.com/features/innovation-invasion
Second, the other consideration from a total energy balance perspective is, how is the electricity used to charge batteries generated? Some other primary energy source must be used to generate the electricity. Electricity is a way to transmit and transfer energy. It’s not an ‘energy source’ on its own.
The fundamental problem is that right now, fossil fuels still provide about 63% of the electricity generated in the U.S., with nuclear an additional 19%. There are significant regional differences, but overall only about 11% of US electric power is generated from renewable sources:
https://www.eia.gov/tools/faqs/faq.php?id=427&t=3
Charging batteries for transportation makes sense in places like Oregon that gets 70% of its electricity from hydro, or California with 33% from renewables, or if you have your own photovoltaic panels that can charge batteries. But not so much in many other places.
Globally, China currently gets 60% of its electricity from fossil fuel, mostly coal, which changes the EV calculation there. Japan is building 22 new coal powered electric generating plants, which together will release about as much CO2 as all the cars sold in the US:
https://www.nytimes.com/2020/02/03/climate/japan-coal-fukushima.html
As a result, in aggregate EVs essentially have a ‘long tailpipe’ to whatever form of primary energy was used to generate the electricity. A report in Scientific American estimated that a Nissan Leaf and Toyota Prius both produce on average about 200 grams of CO2 per mile (though it would be about 100 grams/mile CO2 in California, and 300 grams/mile CO2 in Minnesota):
https://www.scientificamerican.com/article/electric-cars-are-not-necessarily-clean/
Third, with cars there is also a fundamental issue with the way MPGe numbers used for BEVs are calculated, which assume 100% efficiency in converting fossil fuel to electricity. This violates the laws of thermodynamics. Just as internal combustion engines are inefficient, so is the use of fossil fuels to generate electricity. In actuality, only 30-40% of the energy contained in fossil fuels can be converted into electricity in any thermal process (though newer combined cycle natural gas power plants can approach 50%). That means about 2/3 of the energy is wasted (plus about 10% lost in transmission). This has been widely discussed and reported:
https://dothemath.ucsd.edu/2011/08/mpg-for-electric-cars/
https://personal.ems.psu.edu/~radovic/Chapter4.pdf
https://www.forbes.com/sites/warren...-electric-vehicle-mileage-fraud/#54dc4b4929de
https://www.nrel.gov/docs/fy17osti/67645.pdf
With only about 30-35% of the energy contained in fossil fuel actually converted into usable electricity, this means that to put 85 kWh of electric charge into an EV requires 269 kWh of fossil fuel or nuclear energy. For example, a Nissan Leaf that is advertised with ’99 MPGe’ in an apples-to-apples comparison is actually getting the equivalent of 28-36 real world MPG. Not bad, but significantly different than what the MPGe number suggests, and objectively not much better than an efficient ICE car.
The calculation becomes even less favorable when taking into account the environmental impacts of lithium and rare Earth metal mining, battery disposal at end of life, etc.
Of course the situation would be completely different if electricity were predominantly generated from renewable sources (solar, wind, tidal, geothermal, etc.). But at present, only 11% of electricity in the US comes from renewable sources. Hydro generates an additional 7% but has its own issues, including the environmental impacts of flooding regions when dams are built, questions about the future reliability of hydro power because of climate change, and the fact that it’s already fully developed in the US with little expansion ability.
Global warming also has multiple impacts on even green power generation. The drought in California results in dropping water levels, which in turn means less electricity can be generated from hydro power (half this year compared to last) and more fossil fuel plant capacity must be used:
https://www.utilitydive.com/news/ca...-hydropower-share-leading-to-more-nat/624489/
Like most things in life, the solution is going to be complicated, and not simply buying more electric vehicles. At its core, a fundamental need is to change the U.S., and world, electric generating grid to renewable sources. That will take a lot of money. Just for the U.S. it would cost over $5 trillion (let’s call it a nice even $10 trillion with the inefficiencies, corruption, bureaucracy, inflation, and pork in our system):
https://www.renewableenergyworld.co...lace-where-should-infrastructure-spending-go/
Especially in the new coronavirus reality, with the world likely heading into several years of economic difficulties, and the U.S. having to deal with trillions of dollars already spent on ‘economic recovery’, it’s hard to see where and when the money could come from to convert to renewable sources.
The scientific data on climate change are overwhelming (and as a retired scientist I fervently believe the data)(I also often quote Neil deGrasse Tyson's great saying). We need to save our planet and do whatever we can to combat climate change. After all, this is the only planet we have, so not killing it - and ourselves in the process - seems like a really good idea. The horrific forest fires on the west coast of the past few years are yet another example of what we will have more of in the future if we don’t do something. Unfortunately, it’s not going to be as simple as building more EVs.
