Yet another application for biochar looks to be on the horizon; a growing number of studies are proving that biochar could be an effective tool in managing air quality, with one study finding that the charcoal-like material has the potential to significantly reduce air quality-related healthcare costs.
What is Biochar?
Biochar was originally discovered in ancient Amazonian soils and recognized for its ability to bring desolate soils back to life. A carbonaceous material, biochar is a precursor to activated carbon – a highly effective adsorbent already used widely in air treatment applications to remove volatile organic compounds (VOCs), mercury, hydrogen sulfide, odor, and more in a variety of settings.
Like activated carbon, biochar is a porous material that boasts a very high surface area, allowing it to capture and hold on to particles. In soils, experts suspect that these characteristics help biochar to retain nutrients, moisture, and other materials, as well as provide a place for microbes to live. But as more research around biochar is conducted, scientists are finding that there are innumerable settings in which these characteristics can be beneficial. Among them, biochar has recently been acknowledged in potential roles for:
- Removing pharmaceuticals from water
- Aiding plants and soils in drought resistance
- Increasing biomethane production during anaerobic digestion
- Improving digestion and other characteristics in livestock
Researchers are now looking to add air pollution control to this rapidly growing list of applications.
Air Quality: An Escalating Problem
Air quality is a major problem that can have widespread and devastating effects, not only to the environment, but also to human health and even the economy.
Expected increases in air pollutants have experts worried; the Organisation for Economic Co-operation and Development (OECD) estimates that by 2060, outdoor air pollution could be blamed for between 6-9 million premature deaths each year, with air pollution related healthcare costs jumping from USD 21 billion in 2015 to 176 billion in 2060.
As research around air pollutants and their associated effects grows, the use of biochar looks promising in many ways.
Using Biochar to Control NOx Emissions from Soil
While agriculture is not solely to blame for air pollution, it is certainly a contributing factor and has drawn the attention of those looking to mitigate sources of air pollution.
According to Bioenergy Insight, researchers at Rice University have released the results of a study showing that biochar could be a valuable tool in reducing air quality issues, with potential to substantially reduce associated healthcare costs.
Research has already proven that biochar can be used to decrease nitrous oxide (N2O) emissions from soil, but this study, published in the American Chemical Society’s Environmental Science and Technology journal, specifically examined biochar’s effects on limiting nitric oxide (NO) emissions from soil. Nitric oxide reacts with oxygen in the atmosphere to form nitrogen dioxide (NO2).
These nitrogen oxides (NOx) can have a variety of implications on both humans and the environment, contributing to respiratory problems, cardiovascular issues, toxins in the air, smog, eutrophication, global warming, and more.
The Rice University study found that widespread use of biochar in an agricultural setting could reduce NO emissions from soil between 0 – 67%, with various factors contributing to its effectiveness. Using the highest metric, the researchers used health cost models to predict reductions in related healthcare costs.
Ghasideh Pourashem, who led the study, stated, “Our model projections show health care cost savings could be on the order of millions of dollars per year for some urban counties next to farmland.” Urban areas outlying farmland in the Midwest and Southwest would likely benefit the most.
The study specifically named the following counties as those likely to see the highest benefit:
- Illinois: Will, La Salle, Livingston
- California: San Joaquin, San Diego, Fresno, Riverside
- Colorado: Weld
- Arizona: Maricopa
- Texas: Fort Bend
Biochar as a Manure Lagoon Biocover
It’s not just soil where biochar could be applied to reduce air pollutants in agriculture; another recently published study looked at biochar’s ability to be used as a cover for manure lagoons.
Under the criticism of many, lagoons have long served as a management tool for manure on farms. In addition to odor, manure lagoons can release various gases that contribute to air quality issues and greenhouse gas emissions. The gases emitted from lagoons have also proven to be highly dangerous to workers around the pit, who can quickly become overwhelmed by the gases. These gases are toxic to humans and animals and can be fatal. Among the gases released from manure lagoons are methane, nitrous oxide, ammonia, and hydrogen sulfide.
While some alternatives to manure lagoons are on the horizon, lagoons are still the primary option in many settings. Lagoon covers made from biological materials, or biocovers, have been recognized as a potential solution to reducing emissions from manure lagoons, with many materials having been tested and showing varying success in odor control. Biocovers are not currently used on a widespread scale due to some of the challenges they present.
The aforementioned study found one of the two biochar sources tested to be an effective means of managing odor and gas emissions from the lagoons, with a reduction in ammonia between 72-80%. The floating biochar cover also proved to sorb nutrients, and as the study notes, the biochar could then be used as a high-value fertilizer to provide much-needed nutrients.
Biochar has also been looked at as an emissions control tool on farms through other avenues as well. One study found biochar to reduce net methane production from cattle when used as a feed additive. Biochar has also been proven to reduce ammonia emissions when added to poultry litter.
Biochar in Indoor Air Quality Control
According to the Biochar Journal, biochar is also being investigated to improve indoor air quality; it can be mixed with building materials such as plaster, cement and bricks up to 80% to produce a product with excellent insulation capabilities, humidity moderation, and offers a healthier indoor atmosphere and breathing properties, with a myriad of other potential benefits possible. It also allows buildings to be transformed into carbon sinks. It can even serve as a substitute for styrofoam, lending its benefits to the building on which it is applied.
How Biochar is Produced
Like activated carbon, biochar is produced through the pyrolysis of materials such as wood waste, coconut husks, and other biological materials. This pyrolysis process is carried out in the low oxygen environment of an indirect rotary kiln (aka calciner) at temperatures between 500-800°F. Activated carbon is produced in the same environment, but at much higher temperatures and a steam activation step. To learn more about how biochar and activated carbon are made, see our infographic: Biomass to Activated Carbon (and everything in between).
Conclusion
Biochar is an incredibly valuable tool in a number of settings. As research around biochar grows, scientists are finding that in addition to its soil restoration and other capabilities, biochar may also prove valuable in air quality, with recent studies focusing on its use in agriculture. The use of biochar in air pollution control could also hold the potential to substantially reduce related healthcare costs.
FEECO provides custom rotary kilns for processing biomass sources into biochar products and can assist in every step along the way, from initial feasibility testing and process/product development, to custom manufacturing, and even parts and service support for biochar systems. For more information on our capabilities contact us today!