Three excavators organize debris at the former Great Northern Paper Co. mill site in East Millinocket in this March 2017 photo. Credit: Nick Sambides Jr. / BDN

A Portland startup said Wednesday that it plans to lease part of the former Great Northern Paper mill in East Millinocket for a pyrolysis facility to convert low-grade biomass into biocarbon.

Standard Biocarbon Corp. signed a letter of intent with East Millinocket Industrials Inc. to occupy about 25,000 square feet of what was the former mill’s finished paper warehouse. The company, which will be the first tenant in the former mill, plans to launch operations by the fall and hire five people to start.

The storied Great Northern paper plant closed for good in 2014 and 212 workers lost their jobs. It had a series of owners until the town of East Millinocket bought it last July.

Standard Biocarbon’s CEO Frederick Horton said the company will use low-grade wood traditionally harvested for papermaking or power generation to produce biocarbon, which is sold commercially as “biochar.” That product can be used in agricultural applications like compost and for environmental cleanup.

Standard Biocarbon Corp. is leasing part of the former Great Northern Paper mill in East Millinocket to make ‘biochar,” a biocarbon product used in agriculture products like compost and for environmental cleanup.

He said biocarbon, which has properties similar to activated carbon, improves soil productivity and reduces the need for irrigation and fertilizer.

Pyrolysis is a high-temperature decomposition process with heat as a byproduct. Horton said that heat could be used by the East Millinocket factory’s owners to warm spaces for future tenants in the 200,000 square feet of indoor space at the plant.

It takes 5 tons of wood to produce 1 ton of biochar, and the plant’s location close to the wood feedstock was important when choosing the East Millinocket location, Horton said.