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0 pointsncmncm3y ago0 comments

Tractor fuel produced at the foot of a wind turbine in the middle of a farmer's field, that doesn't need to be transported from a refinery, would have immediate value.

Fences made of double-sided solar panels mounted a bit more than tractor-width apart, running N-S, coexist nicely with row crops, and cut water loss, improve conversion efficiency (via evaporative cooling), and often increase yield besides (via reduced heat stress). Producing fuel locally is better than selling the power and buying fuel.

                HH XX HH
                HH=XX=HH <--tractor
                HH XX HH
       crop        XX
       |           XX    | <-panel/fence
       v           HH    |
  x|x  x  x  x|x  x  x  x|x  x  x  x|x
  x|x  x  x  x|x  x  x  x|x  x  x  x|x
  x|x  x  x  x|x  x  x  x|x  x  x  x|x
  x|x  x  x  x|x  x  x  x|x  x  x  x|x 
  x|x  x  x  x|x  x  x  x|x  x  x  x|x
  x|x  x  x  x|x  x  x  x|x  x  x  x|x

0 comments

alex_young3y ago

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

ncmncmOP3y ago

Tractors are very expensive. Farmers will not replace them just for this. And, they need to operate all day long, which would take a hell of a lot of battery.

Retrofitting with ammonia tankage and plumbing (making them cheaper to run) is an expense they might prefer to avoid until they have a reliable secondary supply of ammonia.

throwaway8943453y ago

They need to run all day and all night for ~2 weeks straight twice a year and then they can sit idle most of the rest of the time. But during those 4 weeks charging for one out of every three hours (I’m assuming that a big tractor pulling a big implement is going to deplete even a really big battery fast and charging a battery that large is probably going to take a long time) isn’t going to be tolerable.

tastyfreeze3y ago

It is easier and cheaper to store liquid fuel. Making liquid fuel would allow fuel to be made and stored in the off season in a greater quantity than could be reasonable be stored in batteries.

nyokodo3y ago

> The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power

It depends on how efficient it is to use existing ICE tractors vs creating new electric tractors. If tractors are like other ICE vehicles then something like half the energy they take over their lifetime is used in their production so if you want to get to Net-0 sooner generating carbon neutral fuel might be the way to go.

ncmncmOP3y ago

Efficiency is secondary. Cost is primary. As the cost of generator capacity continues on down, people worry less about efficiency. The top-line input, sunshine, is free. So it is a question of capital cost amortized over energy produced.

1 more reply

seltzered_3y ago

You have to look at gravimetric and volumetric energy density, the book 'the future is rural' has a nice chart on this:

https://twitter.com/vivekgani/status/1426017955398176770?t=0...

ncmncmOP3y ago

Chart omits liquified anhydrous ammonia. Its volumetric energy density is about half of diesel's, with a somewhat better mass energy density. You need bigger tanks that can hold back a bit of pressure, and new plumbing disinclined to corrosion.

It also omits liquified hydrogen, which is inconvenient to handle, but not much moreso than liquified methane.

LgWoodenBadger3y ago

With the amounts of extra weight farmers often add to their tractors, and their general hatred of DEF and regen cycles, electric tractors seem like a billion dollar idea just waiting for someone to pick it up and run with it.

throwaway8943453y ago

I doubt batteries are up to the task. Tractors and implements are big, so the battery is going to have to be huge, which is going to further increase the weight of the tractor and so on. Plus if you’re in the middle of harvest season (you have a narrow window to get crops out of the ground and you work around the clock for a week or so), you can’t afford to wait an hour to charge your tractor after driving it for an hour or two. Anyway, you would have to have electricity in ample supply on site or else you’re taking your tractor offline for even longer while you drive it to and from your field for a charge.

coderintherye3y ago

Solectrac is making electric tractors in production. They are available today (though waiting period between deposit and delivery).

ncmncmOP3y ago

Boutique item, maybe unless the batteries can be replaced while it operates. They would need a hell of a lot of spare batteries, and somebody running around replacing them. Presumably today people are driving out to fill up fuel in existing tractors after some number of rows.

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pjc503y ago

> doesn't need to be transported from a refinery

Given how much cutting edge process chemistry is involved in this fuel manufacture, it will be a long time before it's available in small units, which will of course be more capital-intensive and less efficient than large units because that's how scaling works.

It's far more likely this fuel will end up simply co-mingled with the global market and shipped all over the world from a few sites which are good for generation but not for direct consumption.

DennisP3y ago

According to their "need for speed" page, their plan is to build factories producing units the size of shipping containers. They think they can have three of them by 2030, each churning out a quarter million units annually.

pjc503y ago

... I'll file that under "believe it when I see it". It would be genuinely transformative of the world economy if it happened.

1 more reply

jabl3y ago

> Fences made of double-sided solar panels mounted a bit more than tractor-width apart

Er, tractors often tow implements that are significantly wider than the tractor itself.

ncmncmOP3y ago

They can but are not obliged to.

universa13y ago

While a nice theory, this is not competitive in practice... The capital costs and loss in productivity result in about a 2 to 3 times lower profit per unit of land compared to full solar. Just put solar on the non-ideal fields (iirc about 4% of German AG area would be needed to cover electricity demand with solar)

ncmncmOP3y ago

You miss the point that identically the same land is now producing two revenue streams, one year-round. And, that ag yield is increased. Fortunately, they don't need your approval. It is being done now. Japanese are leading.

ehnto3y ago

It might not need to be 100% of fuel used, subsidizing the fuel supply would be enough I think. It would also allow those farms to claim some of that as carbon credits and other green certificates.

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0 comments

alex_young3y ago

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

ncmncmOP3y ago

Tractors are very expensive. Farmers will not replace them just for this. And, they need to operate all day long, which would take a hell of a lot of battery.

Retrofitting with ammonia tankage and plumbing (making them cheaper to run) is an expense they might prefer to avoid until they have a reliable secondary supply of ammonia.

throwaway8943453y ago

tastyfreeze3y ago

It is easier and cheaper to store liquid fuel. Making liquid fuel would allow fuel to be made and stored in the off season in a greater quantity than could be reasonable be stored in batteries.

nyokodo3y ago

> The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power

ncmncmOP3y ago

1 more reply

seltzered_3y ago

You have to look at gravimetric and volumetric energy density, the book 'the future is rural' has a nice chart on this:

https://twitter.com/vivekgani/status/1426017955398176770?t=0...

ncmncmOP3y ago

It also omits liquified hydrogen, which is inconvenient to handle, but not much moreso than liquified methane.

LgWoodenBadger3y ago

throwaway8943453y ago

coderintherye3y ago

Solectrac is making electric tractors in production. They are available today (though waiting period between deposit and delivery).

ncmncmOP3y ago

1 more reply

pjc503y ago

> doesn't need to be transported from a refinery

It's far more likely this fuel will end up simply co-mingled with the global market and shipped all over the world from a few sites which are good for generation but not for direct consumption.

DennisP3y ago

pjc503y ago

... I'll file that under "believe it when I see it". It would be genuinely transformative of the world economy if it happened.

1 more reply

jabl3y ago

> Fences made of double-sided solar panels mounted a bit more than tractor-width apart

Er, tractors often tow implements that are significantly wider than the tractor itself.

ncmncmOP3y ago

They can but are not obliged to.

universa13y ago

ncmncmOP3y ago

ehnto3y ago

It might not need to be 100% of fuel used, subsidizing the fuel supply would be enough I think. It would also allow those farms to claim some of that as carbon credits and other green certificates.

j / k navigate · click thread line to collapse