A bright yellow expanse of canola flowers about 25 kilometers from the Fukushima Daiichi nuclear plant is providing more than just a blaze of color: The flowers are also helping to remove radioactive cesium from the soil.

The flowers were planted as part of a project aimed at decontaminating land and generating power in Minamisoma, a coastal city that straddles the edge of the evacuation zone around the Fukushima plant.

For Kiyoshige Sugiuchi, a 65-year old farmer from Minamisoma, the blooming flowers represent progress in the project run by a group of seven farmers and volunteers. He says the area covered by the flowers has tripled in size since the project started in autumn 2013 with a much smaller plot of 4.7 hectares.

The goal of the project is to create a chain of decontamination and power generation, using a biomass power station to make electricity from methane given off by fermenting canola.

Cesium is now virtually the sole cause of radioactive contamination in the area around Fukushima. Canola has been used to absorb cesium in areas surrounding Chernobyl to decontaminate farmlands there, but it only absorbs a small amount of cesium each time. It will therefore take many years to decontaminate the soil in Minamisoma.

Methane is produced by fermenting the canola leaves, stalks and roots, though the fermented residue has to be treated as low level radioactive waste. Canola oil, also known as rapeseed oil, can also be extracted from the seeds without any cesium content.

So far, the canola project is being run on a volunteer basis with some donations. The team is also selling the oil to raise money, though not in large volumes yet.

“In this area, rice was the main commercial product. But it’s difficult to get back the past as it was, given that many consumers are avoiding food from Fukushima. We have to come up with a new business model that doesn’t rely very much on markets in the outside world,” Mr. Sugiuchi said.