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

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?

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.

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.

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.

> 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.

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.

> Efficiency is secondary. Cost is primary.

While the question I was responding to was explicitly about efficiency, you might be right about cost. However, ICE tractors that are already owned along with the capital required for their use and maintenance are potentially a lot more attractive to keep vs new electric tractors. Sunshine might be free but it’s not available in sufficient quantities everywhere with current technology, and all technologies will require ongoing maintenance. With China becoming an untrustworthy trade partner the cost of solar panels will likely rise. If they do I hope they can make affordable efuel so that we make progress either way.

Solar panels are produced in many more places, now. (Former-Soviet) Georgia produces a very great number of them, for example, at exemplary prices.

There is plenty of sunshine most places if you can bank fuel during off-season. Finns will probably still need to import from the south or via transmission line if the wind is off -- as they have done for many decades on a more regular schedule.

> There is plenty of sunshine most places if you can bank fuel during off-season

Energy storage is woefully insufficient yet to cover days let alone seasons so that is a very big "if."

You seem to be saying you think keeping liquid fuel in tanks does not qualify as storage. If that is what you mean, you will need to explain why you think that, because it makes no sense.

If you mean we have not yet built out as much storage as we will ultimately need, because we anyway haven't enough renewable generating capacity built out yet to charge it from, then yes we know. The solution to that is obviously to continue building out renewable generating capacity, and then storage for the excess.

> You seem to be saying you think keeping liquid fuel in tanks does not qualify as storage.

I just misread what you wrote. I didn't see "fuel" and thought you were referring to other means of renewable storage. Fuel as an efficient and much less geographically limited means of storage makes a lot of sense.

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...

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.

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.

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.

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

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.

Yes and no. It's not targeted at massive monoculture farms such as corn farms in the Midwest. Rather it is targeted at operations where a smaller tractor with a few hours runtime is useful. That includes not only hobby farmers but also vineyards, etc.

> 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.

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.

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

Indeed it would. It certainly wouldn't be possible if they needed heat and pressure. See this part of the article:

> Our Fuel Forges are similar in many ways to hydrogen electrolyzers, in that they consist of many layers of cells, each consisting of a cathode, an anode, and a separator. In an H2 Electrolyzer, the anode is where electrons are stripped from water, producing oxygen, and the cathode is where electrons are added to protons, producing hydrogen gas. In our system, the anode works the same way, but our cathode, in addition to making H2, also makes liquid fuels. Both systems have capital costs dominated by the costs of the electrochemical stacks.

> This brings us to the issue of economies of scale. For high temperature / high pressure systems like Fischer Tropsch or e-methanol to gasoline (MTG), economies of scale mean large refinery installations that cost billions of dollars and years to build (and still don’t get to cost-competitive fuels). For modular, mobile systems like our Titan Fuel Forges, however, economies of scale mean mass manufacturing.

Heat and pressure are readily available in small-format equipment.

What would make a difference are whether it is expected to start and stop operation, how much supervision it needs, and how much customization is desirable. The quoted text above cites ability to manufacture mass numbers of units, and by implication to distribute, install, and operate them with minimal attention to details.

> 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.

They can but are not obliged to.

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)

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.

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.