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  • Over the last several decades, we've poured billions of dollars into biofuel research...so

  • why can't you fill up with it at the gas station yet?

  • Where are the biofuels?!

  • After all, the gas you put in your car is essentially an ancient biofuel: it used to

  • be organic mattermostly algae, actuallythat over millions of years was compressed within

  • the earth into fuel, hence the term fossil fuel.

  • It consists of hydrocarbons, which we can burn, breaking those bonds to release energy

  • that powers stuff, like our cars.

  • So surely in this age of modern science, we can engineer new fuels out of those same raw

  • materials, right?

  • Turns outnot so simple.

  • See, the idea behind biofuels is that we use organic matter, like straw or corn or sugarcane,

  • and turn it into liquid fuel.

  • Ideally, the gases that are released when we burn that fuel are equivalent to the emissions

  • that are absorbed by growing them in the first place, so the whole cycle is what we call

  • 'carbon neutral'—it produces zero net emissions.

  • Plus, we won't run out of them, because we can just grow more.

  • That's why biofuels are so attractive.

  • We could have energy security and reduce emissions, even create whole new agricultural sectors.

  • But the amount of energy that's packed into really potent fossil fuel is pretty hard to

  • rival.

  • Take ethanol, a common first generation biofuel.

  • It's an alcohol, which requires plant biomass to be fermented, distilled, and dehydrated

  • to take it from the crop we grow in the field to what you put in your tank.

  • In the U.S., for example, we've mostly used corn, and just growing it in the first place

  • requires intensive resourcesnot just energy, but land, water, fertilizer that causes pollutionand

  • growing corn for ethanol can directly compete with food production.

  • After growing it, we have to process the raw corn into fuelthis is time, money, and

  • energy expensive.

  • Plus, actually putting ethanol in cars is a bit of a stumbling block.

  • In general, if we want to use different fuel, we'll have to change the way we make most

  • cars, especially in the U.S.

  • And ultimately, creating ethanol is so resource intensive, these fuel products can actually

  • end up producing even more emissions than fossil fuels throughout their lifetime!

  • Scientists have recognized these failures in recent years and have developed more efficient,

  • second generation ethanols out of cellulosic material, the denser, inedible parts of crops.

  • This doesn't compete with existing food pipelines and actually results in more energy

  • payoff.

  • But the distillation process remains expensive and energy intensive--it may be more energy

  • dense material, but it's also harder to break down into fuel in the first place.

  • Brazil has had more success with sugarcane ethanol production, but all ethanols still

  • have yet to break even in terms of practical, widely-used energy parity.

  • Ok, but ethanol's not the only biofuel out there.

  • We also make biofuel out of algae, which--again--involves cultivating and harvesting these microorganisms,

  • then putting them through an energy-intensive process that squeezes those lipids out of

  • the algae cells.

  • We then refine those oils, and turn them into fuel.

  • Same kind of problems here as with ethanolwe haven't been able to turn this process into

  • something that, on the whole, creates less emissions AND is less expensive than regular

  • fuel because of all the resources that go into processing it.

  • Plus--these organisms are plagued by predators in large cultivation ponds, and keeping them

  • alive in industrial quantities is tough...but lots of cool research is going into fixing

  • these particular problems.

  • What if we took an already processed food by-product, like used french fry grease, and

  • used it as fuel?

  • We just need to refine it a bit, through a process called transesterification, into something

  • call hydrotreated vegetable oil (HVO).

  • This can and has been used to fuel large cargo ships, and produces less carbon dioxide and

  • polluting particulates than the traditional fuel for these large, energy-intensive vehicles.

  • These materials are more energy rich than first gen biofuels like pure ethanol--but,

  • you guessed it, the conversion process is still really expensive.

  • And biofuel like this works primarily with diesel engines, which aren't as common in

  • some places around the world, like in the U.S..

  • In some places like Sweden however, HVO already makes up a vast majority of their biofuel,

  • and biofuel in general makes up about a fifth of their transport fuel sources.

  • So it is a promising contender.

  • We've been trying to make biofuel work commercially since the early 1900s.

  • And we're still not there yet, but we are innovating.

  • Scientists are now genetically editing plants to make them produce more of the fatty oil

  • we use to make the fuel, hopefully allowing us to get a higher energy yield from the resources

  • we put into cultivating that organism.

  • And some experts think that even as the market shifts toward electrifying cars and trucks

  • on the road, biofuel is still a valid option for powering big, pollution-heavy vehicles

  • like container ships and airplanes.

  • Maybe the real problem is how we've been talking about all this--everyone wants to

  • hype biofuel as the thing that's going to save the world, but we're still on the journey.

  • Hopefully we won't give up quite yet because there's really exciting technology in the

  • pipeline that could get us there, and that needs support.

  • But the clock is ticking and it feels like time, and patience, is running out.

  • What do you think about biofuels?

  • Still promising, or will something else beat green fuel to the road?

  • Let us know in the comments below, and if you want to always check in on big questions

  • like this one, don't forget to subscribe to Seeker.

  • Thanks for watching!

Over the last several decades, we've poured billions of dollars into biofuel research...so

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為什麼我們還沒有功能性生物燃料? (Why Don’t We Have Functional Biofuel Yet?)

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    林宜悉 發佈於 2021 年 01 月 14 日
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