[andrewflnr]

> Plants have very low sunlight conversion efficiency compared to solar farms.

Measured how? If nothing else, they seem to be good at carbon capture. And I don't see how you it could account for engineered for plants engineered to store more of their energy as oil.

[philipkglass]

Measured by the fraction of incident sunlight that gets transformed to usable energy. Solar farms generate about 30 times as much power per hectare as corn farms, assuming that you can use electricity directly:

"Ecologically informed solar enables a sustainable energy transition in US croplands"

https://www.pnas.org/doi/full/10.1073/pnas.2501605122

As a rough estimate, you'd lose 2/3 of that energy if the electricity had to be turned into liquid fuels. That would still mean 10 times greater usable energy produced per acre.

Plants genetically engineered for fuel production might be somewhat more efficient in the future, but future solar farms are also probably going to be more efficient.

[mikeyouse]

For anyone wanting to learn more - the holy grail of Ag engineering would be to increase the efficiency of rubisco, which is the rate-limiting enzyme in photosynthesis - so understandably there’s a ton of research at doing just that.

https://en.m.wikipedia.org/wiki/RuBisCO

[JumpCrisscross]

Strongly recommend for one of the light-dependent reactions from before that enzyme: https://youtu.be/WhCczIqADuI

[murderfs]

A somewhat less (but still!) ambitious project is to retrofit C4 photosynthesis into rice. It's something like 50% more efficient, and has evolved independently dozens of times, so it's probably a lot more feasible.

[rendaw]

Why do we need more efficient photosynthesis in plants? Is it for indoor cultivation?

[mikeyouse]

If you had a widely applicable improvement, you’d be able to grow fruit trees in Canada or have two harvests in one season for food crops, or grow much denser species of wood, much more quickly for construction lumber. It would be massively world changing — but it is a 4 billion year old enzyme so is pretty entrenched..

[rendaw]

Oh interesting! Is photosynthesis the main thing limiting growth speed?

I would have expected there to be multiple processes with similar or aligned timings, or some built in limiting mechanism or something... it's not like giving humans higher calorie food makes them become adults faster.

[mikeyouse]

Improving rubsico would be more along the lines of improving your metabolism so that you can process 4,000 calories per day with the loose analog of supplying more CO2 being the ‘higher calorie food’. It’s the single largest bottleneck in photosynthetic efficiency. TBH, it would likely take several more breakthroughs for plants to make use of an improved rubisco but it’s still a massive target for ag research.

[melagonster]

Plants get more energy, so they generate more food.

[andrewflnr]

Ok, yeah, if your reference for biofuel is corn, where you can only use a tiny fraction of the plant, no kidding it'll look bad.

[andsoitis]

Which plant do you estimate is a much better pick?

[andrewflnr]

Either a perennial with oily fruit (someone mentioned palm oil down below), or something where you can relatively easily use the entire plant. The idea I keep coming back to is algae bred or engineered for oil content, but I'm not actually sure how feasible that is.

[KnuthIsGod]

https://hakaimagazine.com/news/biofuel-made-from-algae-isnt-...

[andrewflnr]

> Mayali says that growing phytoplankton outdoors with natural light and finding a less energy-intensive method of powering production would help microalgae-based diesel compete.

I'm sorry, were they measuring the carbon footprint of growing algae by what it takes to grow it inside with artificial light?