Pure speculation on the transportation energy density challange

Batteries suck. ~80% efficient charge and discharge cycles and low relative energy densities pose problems for builders of electric transportation. Tough shit, we need to figure this one out.

Batteries themselves are the subject of furious research in the material sciences world (carbon nanotubes and 3d printing!! don’t’cha know will one day revolutionize everything in sight !) squeezing the watt-hour/kg ratio as far as we can means a lot to electric vehicle development.

The other side of the equation is vehicle construction. Lightweight materials and design efficiency are crucial. Both lightweight materials and cutting edge battery technologies are expensive. (Alu .92c/lb, Carbon Fiber $9/lb, compared to Steel .14c/lb)

What does this mean for the garage builder or small manufacturer today ? It mostly means that projects end up falling into a few categories based on capital, and most are 1-2 seater trikes or even bicycle based vehicles.

Most of the impressive looking lightweight EV projects out there are one-offs looking for funding (1, 2) or plans to DIY, but the bike based stuff you can buy tomorrow from a manufacturer (organictransit.com)

The message here is that currently, really effective, cheap EV’s that can sit in your garage within a few months don’t look like cars. This in the long term is not a bad thing. The design rooms of major automakers are stuffed to the gills with concepts of small lightweight vehicles. If some yokel in his garage (me) can see the trajectory of personal transportation shrinking in size and weight, they can too. But will it sell ?

Enter the VW XL1 a 260mpg hybrid built from CF and Alu. Pricey ? you bet. Limited number ? you bet. To suffer the same fate as the EV1 ? …. uh, I’d hope not.

This is the direction we are headed, the absolute shaving of weight from transportation has to occur if we are to think about electrifying vehicles and using batteries, the battery weight as a percentage of gross vehicle weight has to be large given batteries current constraints. This is how the energy density challenge might be solved, for a spell.

The long view

In the long term, average vehicle weight of the national fleet will come down, commute distances will shrink, increased locality of supporting infrastructure and thus shrinkage of supply lines will occur. We can hope this happens with as few hiccups as possible.

A fundamental change in what wheeled transportation means is occurring, driven not only by an eventual liquid fuels crisis but by (perceived) environmental benefits.

The days of 5,200lb trucks carrying a single person and no cargo are numbered. Major questions result from the thought of electrifying current transportation needs, resource constraints and current grid capabilities are a couple of big ones.

It is illuminating to ponder the concept of what such a shift looks like, demand for mobility is not likely to decline, but as today, people will continue to try every conceivable form of vehicle.

An interesting concept arises when we consider what drives this push for electrification. In my case my advocacy is two fold, not only out of a concern for more efficient use of energy but also that conventional transportation fuels are due for their sunset. The decline of the petrochemical industry on the 50-80 year horizon though highlights the fact that EV’s as they currently exist today are a transitory period in transportation.

What will we be driving in 100 years ?

Given that manufacturing and all forms of power generated today indirectly rely on either petrochemicals and/or extractive industries, what on earth supports mass mechanized transportation when these things become unviable ?

Mining and manufacturing are technically already well position as large consumers of electricity, certain renewables and nuclear power can help us sustain their prospect.

I don’t have much insight into the recyclability (& efficiency of recycling) or peak extraction rates of everything needed to build an EV, but you can bet that they vary widely in their prospects and substitution ability, hence a large amount of research needs to go into painting a picture of what the 100-year vehicle looks like.

Many will likely posit that horses and a return to living exclusively on current sunlight are where we are headed, on the 3-400 year horizon this might hold true.


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