The new knowledge has been published in the journal Frontiers in Plant Science.
Among switchgrass's attractive features are that it's perennial, low maintenance and native to many states in the eastern U.S., including Michigan. But it also has a peculiar behavior working against it that has stymied researchers - at least until now.
Berkley Walker's team in MSU's Department of Plant Biology has revealed why switchgrass stops performing photosynthesis in the middle of the summer - its growing season - limiting how much biofuel it yields. Walker, an assistant professor in the College of Natural Science also works in the MSU-Department of Energy Plant Research Laboratory.
Mauricio Tejera-Nieves, a postdoctoral researcher and the lead author of the team's study said, "We want bigger plants, period, so being able to crack this and lift this limitation, that is the goal."
Tejera-Nieves, Walker and their colleagues discovered the explanation for this limitation in switchgrass's rhizomes. These are little knobby structures that live underground among the plant's roots. If you've ever sliced or shredded ginger, you've held a rhizome.
Rhizomes store food in the form of starch to help plants survive winter, and that starch is made from the sugars produced by photosynthesis. Once switchgrass rhizomes are full of starch, they signal the plant to stop making sugars and adding biomass through photosynthesis.
Tejera-Nieves compared the rhizomes to a bank, albeit a slightly unusual one.
"Imagine getting a call from your bank and they tell you, 'Hey, your account is full. You can take a vacation, go on sabbatical, do whatever you want. Just stop working because we're not storing any more money,'" Tejera-Nieves said. "It's a very conservative strategy, but it's one that works for switchgrass. The longer it's doing photosynthesis in nature, the more likely it is that an animal will eat it or something else bad will happen."
Although this evolutionary strategy has worked to the plant's advantage in nature, it is a disadvantage for humans who want to ferment switchgrass's biomass into biofuel. By understanding the root cause of this behavior, though, researchers can start looking for ways around it.
"Now we can start looking for breeding solutions," said Walker. "We can start looking for plants that have an insatiable appetite for photosynthesis."
***
We haven't been seeing nearly as much biofuel news as we did a few years ago. Biofuel news isn't rare but it has become unusual.
That makes news like this quite a relief. Biofuel is the most competitive energy store vs the fossil fuels. The production moderates prices and allows Brazil and the US to be more independent from the world petroleum market and by that levels the world price of crude oil.
The production hope is that switchgrass and miscanthus will grow profitably on the soils not needed for food crops. That could very well happen and sooner perhaps than the next crude oil demand level increase or production level decrease. The technology might be ready for production investment.
What is yet to accomplish are the processes break down the lignin and that produce the fuels in the more energy dense range such as butanol.
The objective view has this research as very useful indeed. The probability is the fuel products are drop in to the existing fuel infrastructure.
Good valuable work there at Michigan State!
By New Energy and Fuel
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Brian is the editor of the popular energy technology site New Energy and Fuel. The site’s mission is to inform, stimulate, amuse and abuse the… More