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How to improve crop yields while reducing climate change

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With a one-two punch aimed at reducing climate change and improving crop yields worldwide, re:char is turning agricultural waste into soil-improving biochar.

With a one-two punch aimed at reducing climate change and improving crop yields worldwide, the for-profit company re:char is turning agricultural waste into soil-improving biochar.

I spoke last week with re:char founder Jason Aramburu, a 2009 PopTech fellow, about how biochar works -- and how it succeeds in an ambitious double-barreled mission.

What is biochar and how do you make it?

Biochar is a carbon-negative soil amendment made from waste. It's produced through a process called pyrolysis. We produce it using specially-designed proprietary kilns that quickly heat biomass up to very high temperatures with no oxygen.

Why is biochar important? What does it do?

Biochar can be burned just like regular charcoal. In a place like Africa, that's a big deal. Beyond that, biochar is added to soil. It holds onto nutrients, water, microorganisms. It improves crop yield. Because it's made from decomposing waste that would otherwise go back into the atmosphere, when it's converted to charcoal we can sequester that carbon in the ground. We convert it into a form that will never decompose back into CO2.

What's the history of biochar?

It actually originates in the Amazon. About 2,000 to 3,000 years ago, farmers would make charcoal and bury it in the ground. They did this for the crop yield improvement. If you go to these sites today, you'll see that the charcoal is still intact in the ground and the soil is black. We call those terra preta. It means dark Earth.

Talk more about how biochar affects soil.

When you put the biochar in the soil, it's like putting a sponge in the soil. Biochar has very high surface area, so it soaks up everything around it. Traditionally when you fertilize or water your crops, you lose a lot of it. The fertilizer runs off or it doesn't get in the soil where it needs to be. With biochar we can actually capture more and hold it in the soil. We find that over time biochar also creates an ideal environment for microorganisms to live, things like fungi and bacteria. Those are crucial for plant growth and crop yield.

Do you sell biochar now?

We're developing equipment to make biochar. We have two systems. One is for the developed world. It's a product that will produce biochar continuously at high levels, along with liquid fuel. We're also producing a very low-cost product for the developing world. We're rolling that out in rural Kenya. That product will only produce biochar.

Talk about the liquid fuel that can be produced by the device for the developing world.

It's called bio-oil. It's a low-grade crude oil substitute. We can upgrade it to a point where it can run a diesel generator. It is primarily targeted for [operations with] a lot of biomass in a small area, so forestry operations or large farms, for instance.

How much can biochar improve crop yields?

There has been quite a bit of study on this. We find that in the U.S. and Canada, biochar can increase crop yields between 20 and 30 percent. In a place like Africa, we find it can actually improve crop yields by up to 200 percent. That's partially because they're starting with a lower baseline. Africa has some of the worst soil in the world.

How much do your products cost?

We're still fixing the price to the developed world system. That's a year or more away from launch. In the developing world, it's really interesting. Charcoal is big business in Africa. Up to 80 percent of people rely on it as a fuel source. The price of charcoal is highly volatile. It can be anywhere from 11 cents a kilo to 30 cents a kilo. We price the biochar according to what the going rate is for charcoal in a village. That ensures that people can afford it and can use it for whatever purpose they need.

What's the biggest challenge you're facing as a start-up? Is it funding?

With funding, we've been pretty fortunate. We just got a great grant from Echoing Green in New York. They've been supporting our work. It's getting on the ground and building the momentum around biochar that's been the real challenge. Everyone in the biochar community thought the Cap and Trade bill was going to happen and that would be a big boost for biochar. Then it didn't. Educating the public about it, that's been the real challenge.

What's your background?

I went to Princeton and I studied at the Carbon Mitigation Initiative. It's a think tank developing low-carbon energy technologies. I also did soil science work with the Smithsonian in Panama. I was working on soil science issues with small farmers there. I have this dual background that's ideal for biochar.

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Christina Hernandez Sherwood

Contributing Writer

Contributing Writer Christina Hernandez Sherwood has written for the Los Angeles Times, Newsday, the Philadelphia Inquirer, Diverse: Issues in Higher Education and Columbia Journalism Review. She holds degrees from the University of Delaware and Columbia University's Graduate School of Journalism. She is based in New Jersey. Follow her on Twitter. Disclosure