Since Iowa State emphasizes agriculture, there are students like Rivka Fidel, graduate assistant in agronomy, who research the benefits of bio-char.

“Bio-char is charcoal that’s been made to put in the soil,” Fidel said. “You make it by a process called pyrolysis or gasification.”

Pyrolysis is a thermochemical process that uses bio-mass to produce bio-char, bio-oil or syngas, otherwise known as synthesis gas.

Pyrolosis decomposes organic matter without producing much carbon dioxide at all. It produces carbon monoxide and hydrogen that can be burned as syngas, which burns similarly to methane. Also, it could be burnt at the power plant here, she said.

Bio-char originated from the Amazon rainforest. The soil there, called terra preta or “black earth,” is a soil that is permanently fertile, allowing anything to grow on its surface. This type of soil was located where old villages used to be, and pieces of charcoal were discovered in the terra preta. 

Bio-char has a number of purposes. It returns soil nutrients and carbon usually lost from farmers harvesting the crops and the soil itself when it decomposes. 

“Over time the quality of the soil will go downhill and the ability to produce crops will go downhill, which means you’ll have to add more fertilizer, more tillage every year in order to maintain your yields,” said David Laird, professor in agronomy. “It’s a vicious downhill cycle by removing that residue.”

Carbon helps the soil clump together the way it’s supposed to so it drains properly, helps retain moisture and acts as a sponge to hold nutrients where they need to be, said Catherine Brewer, graduate assistant in chemical and biological engineering.

“The idea with bio-char is that the majority of the nutrients that are plant nutrients aside from carbon, they’ll all end up in the char when you do pyrolysis, and if you put that back on the field, all of those nutrients you took off for the most part are put back on,” Brewer said.

“We’re gradually losing carbon from the soil as it oxidizes, so the idea’s here — you’re not only taking it out of the atmosphere and sequestering it in the geosphere somewhere, but you’re returning organic carbon to the soil that it’s been losing, so it builds soil carbon and with that soil properties that we want.”

Bio-char benefits the soil and serves as a cleaner energy source compared with alternative fossil fuels. Pyrolysis in particular, which has three different methods, produces cleaner fuels.

Slow pyrolysis is what traditionally makes charcoal, which can be combusted to produce energy and emit lower amounts of sulfur.

“If you combust bio-char as a replacement for pulverized coal, you will have much lower emissions of sulfur oxides than you would by combusting coal, but you would have comparable emissions of nitrous oxides, various levels of oxygen and those need to be controlled by various mitigation technologies,” Laird said.

Fast pyrolysis maximizes the amount of liquids produced, otherwise known as bio-oil.

“Pyrolysis will produce bio-oil which you can refine much like you can refine crude oil into an ethanol bio-fuel,” Fidel said.

The key product of this would be renewable energy, which could be in the form of electricity or transportation fuels. You can produce other synthetic products such as asphalt with bio-oil, Laird said.

The advantage of fast pyrolysis is the ability to produce liquids, making energy sources that work in a mobile environment, which is where fast pyrolysis comes in, Brewer said.

Gasification, which is what produces syngas, emits cleaner emissions and is another alternative to producing energy.

The bio-mass also can be a potential contributor to reducing the amount of carbon in the atmosphere. Laird discussed how each year plants decay and emit CO2 emissions back into the atmosphere, emitting about 61.5 giga-tons of carbon. The oceans pull out about 2.2 giga-tons of carbon per year, humans who burn fossil fuels for energy emit about 8 giga-tons of carbon and Laird speculated that on average, the increase of carbon in the atmosphere is 5 giga-tons annually.

“If we were to intervene with a pyrolysis, bio-char industry, here the assumption is, if we take 1.3 giga-tons of this carbon that is annually decomposing and taken back into the atmosphere and send it instead to a pyrolysis system, with the production of 0.4 giga-tons of bio-char which would be sequestered in soils and about 0.5 giga-tons would end up replacing fossil fuel carbon, reducing the emissions from 8 to 7.5,” Laird said.

“It would be a potential way to intervene in that cycle in a way that would simultaneously produce renewable energy, therefore displacing fossil fuels and produce a form of carbon that is highly stable, and because of its stability it would help us literally remove carbon from the atmosphere.”

Fidel is currently incorporating bio-char with soil samples to observe the results, speculating that it’s possible for the pH level to increase, which is great for the soil.

Brewer works with the properties of bio-char and what works best with the soil, along with the process of making bio-oil, which she and her colleagues are beginning in the following stage. They will examine what to do with the bio-oil, hoping it will result in bio-oil as a marketable product.