Why BEVs are not meaningfully more efficient than other kinds of green cars (even if you assume everything they say about BEVs is true!)
Part I: The law of diminishing returns
So for a while now, BEV advocates have endless extolled the supposed superior efficiency of BEVs. I'm sure everyone reading this post have at least heard of that argument. What people haven't realize is that this is only true when compared to conventional ICE vehicles. It is not true against other green cars such as hybrids or fuel cell cars. Now, most people who support hydrogen cars already know that the efficiency of BEVs have been exaggerated. But that is not the point of this post. The point is that even if you assume everything they say about BEVs is true, it is still not meaningful more efficient!
The reason being is simple: The law of diminishing returns. The problem is that there is only so much useful efficiency that can be extracted. Only so much waste to be eliminated. Beyond a certain point, you are spending more resources pursuing efficiency than you get back via that efficiency (more on that in part II). This is analogous to the classic example of throwing good money after bad.
To explain what I mean, let's list the efficiency numbers of BEVs, FCEVs, and hybrids when compared to the average car being sold in the US. All of these numbers are pulled directly from the EPA numbers. In fact, I am pulling the highest numbers I can find. I am simply taking them as is, and I make no qualms over how valid they are. This is to ensure that this is done impartially. The only thing to note is that I'm comparing MPGe to MPG, using the assumption that 1 gallon of gasoline is 33.7 kWh (this is a standard assumption):
A BEV with a fuel economy of 141 MPGe
An FCEV with an 74 MPGe
A hybrid with an 56 MPG
A conventional car with an 25 MPG (this is the average fuel economy of new cars sold in the US)
At first glance, the BEV looks significantly more efficient than the rest. But people who are familiar with this terminology will know that it is the wrong way to look at it. The better way to measure it is via amount of fuel consumed per distance. In Europe, this is usually defined as L/100km. For this example, I will use a different one for convenience sake: Gallons per 1000 miles, or GGE (gallons of gasoline equivalent) where applicable:
Type of car
MPG/MPGe
Gallons/GGE per 1000 miles
BEV
141
7.09
FCEV
74
13.51
Hybrid
56
17.86
Conventional car
25
40
When you list things like this, you immediately can tell how much fuel you are really saving. And by doing it this way, you should notice something: The biggest jump is going from a conventional car to the hybrid, a savings of 22.14 gallons per 1000 miles. The FCEV and BEV nets you a decrease of 26.49 and 32.91 GGE per 1000 miles respectively. These later drops are comparatively smaller than the first. But the real interesting part is how minor the suppose big increase in efficiency at the top of the chart really becomes. As a percentage of how much fuel the conventional car is using, the BEV is only saving 27% when compared to the hybrid. And compared to the FCEV, it is just a paltry 16%!
This is the law of diminishing returns in action. You already saved more than half of the maximum possible fuel savings with just the jump to the hybrid. The rest is just gravy and not really that big of a deal. This is also the reverse of what many BEV fans have said. They are often adamant that BEVs have this giant efficiency gap, but rarely do the mention that the competition is already very efficient and further improvements net you very little in terms of actual gains.
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