Biogas (RNG)

The Verbio Nevada Biorefinery, located in Nevada, Iowa, is the first industrial scale renewable natural gas (RNG) facility in North America, using agricultural residues as its feedstock. RNG production from corn stover began in December 2021 at the Nevada plant. The company expects to be operating more biorefineries in the USA. Second is now under construction in South Bend, Indiana.

  • Verbio has developed the technology to produce RNG from pure cellulosic material, such as the agricultural feedstocks of corn stover or wheat straw.
  • Once the bales are put into storage and checked for moisture percentage, the stover is then loaded onto one of two conveyer belt lines and sent through the hammer mill to break up larger pieces. We filter those through a screen, add water to it, mix it up and send it to our digesters for food.
  • In the fermentation tanks we then produce raw biogas, comprising of 55% methane and 45% carbon dioxide. The carbon dioxide and other impurities are removed through a biogas treatment process, leaving nearly pure RNG gas, which is the chemical equivalent to the fossil fuel natural gas. After making sure the gas meets specs, the RNG is then compressed to grid pressure and injected into the Alliant Energy natural gas distribution grid on site. It is used both regionally and throughout the country.

Following the production cycle, any unfermentable material in the tanks will be removed and further processed. This material becomes digestate or humus, a soil amendment similar to compost. It is then sold back to local growers and returned to the fields to restore the nitrogen and phosphates, along some of the carbon contained in the corn stover.

  • Renewable natural gas from the Verbio Nevada Biorefinery is injected into an Alliant Energy pipeline before being distributed across the country. Alliant Energy delivers the energy from the production at the facility to its natural gas customers in Iowa. Further, the company helped to develop standards and regulations for RNG as well as constructed interconnection options for the site, allowing Verbio to comply with requirements established for the sale of RNG in other states.

  • The basis for our RNG is cellulosic feedstock – or crop residue. Fresh stover bales collected each harvest from local growers, 30-50 miles from our plant, are the basis for our biogas production. Removal of the corn stover increases grain yield and mitigates the emission of greenhouse gases, resulting from the degradation of the ag residues on the field. So growers not only have an extra source of income being in business with us, but also increase their own performance and help protect the climate.