New research by Purdue University has examined how farmers could raise enough bioenergy crops to inexpensively produce nitrogen-based fertilisers and reduce the reach of those fertilisers into nearby waterways.

The research was carried out by Purdue University scientists, and led by Nick Capita, a Professor in the Department of Botany and Plant Pathology.

“Use of biomass as the source of hydrogen and energy for ammonia fertiliser is competitive with electricity as a replacement for natural gas or other fossil fuels,” the researchers explain.

“Moreover, the integration of a perennial biomass crop as a border row to food crops is particularly appealing because it provides the substrates for fertiliser production while mitigating the environmental impact of excess nitrogen.”

Researchers at Purdue University estimate that farmers could use 5% or less of their fields to grow enough bioenergy crops, such as sweet sorghum or a perennial grass such as switchgrass, to create the fuel needed to produce nitrogen fertilisers like ammonia.

According to the research, not only would using bioenergy be a more environmentally friendly choice than natural gas or coal, but the crops would be used on the edges of fields as buffers to limit the amount of nitrogen that washes from those fields in local waters.

“It’s a small amount of a grower’s acreage to make the energy needed to completely satisfy the fertiliser needs for an entire field,” Capita explains.

“You could apply 150 pounds of nitrogen per acre, which is more than enough, and you’d need only 5% of biomass per acre. The biomass has a bonus. Where you grow it could improve ecology.”

The biomass crops could be gasified directly or turned into H2Bioil for transport to the gasifier, giving a source of hydrogen needed for ammonia and energy to power the production.

The technology could also be beneficial in developing countries where mobile processing plants or smaller chemical plants could bring production close to farms that lack access to nitrogen-based fertilisers.

Researchers working on the project said the biomass strategy for ammonia production likely would be feasible sooner in sub-Saharan Africa, where soils are low in nitrogen and there is little fertilizer production in the region.