Background Across Europe, increasing quantities of former industrial land are left abandoned, creating so-called “brownfield” sites. Estimates suggest a vast supply of this brownfield land exists across Europe, perhaps as much as 2-4 million ha. These are typically available for potential re-development, however they are often contaminated by metals, making them unsuitable for human use and posing a threat to groundwater. Soil on this type of land can be polluted and expensive to clean up, dry and dusty, or simply non-existent. Current on-site remediation practices are energy intensive and costly. Therefore, the soil is often excavated and removed from the site as hazardous waste – a method that merely relocates the polluted soil, leaving the problem of its decontamination unsolved. Objectives The BioReGen - Biomass, Remediation, re-Generation - LIFE project sought to demonstrate how certain high productivity plants can act as bio-accumulators of particular metals contained in the soil in which they are grown, thereby offering a cost-effective option for the remediation of contaminated brownfields. BioReGen’s main aim was to demonstrate that it could grow plants in poor soil conditions and thus help clean-up the land, make areas look greener and provide a habitat for wildlife. Furthermore, it targeted the growth of plants that could also be used as biomass crops to generate heat and power, thereby contributing to the mitigation of climate change. The project aimed to demonstrate the viability of its approach of growing plants on brownfields on an industrial scale, applying the method to a variety of contaminated sites. Results The BioReGen project successfully demonstrated that cultivation of plants on brownfield sites could not only improve the local environment on the affected areas, but also supply valuable biofuel without impacting on agricultural land. The team planted three small pilot brownfield sites: an old clay pit filled with ash from household coal fires; part of an oil refinery; and spare land in a large iron and steel works. To provide a comparison, it planted two greenfield sites: an eco-park and farmland. Using learning from the pilot stage, the project planted potential energy crops on five demonstration-scale former industrial sites of at least 100m x 100m: a shipbuilding yard; an iron and steel slag heap; a coal mine and coke works; a sewage works; and a council tip. It tested four crops: short-rotation coppice - regularly cut willow trees; miscanthus - elephant grass; reed canary grass; and switchgrass. The team prepared the larger sites by clearing grass, weeds, bricks and rubble and ploughing green waste compost of different thicknesses - 5, 10 or 15 cm - into the ground. Planting tested different methods based around seed scattering, step- or potato-planting machines. Finally, the sites were rolled to help bury the seeds, stems and rhizomes, and appropriate fencing erected to prevent rabbits eating young shoots. The crops were harvested on at least two occasions and analysed for contamination. Further studies assessed the crops’ usefulness as biofuel, testing their firing capability, their suitability under a range of energy producing scenarios and economic feasibility. The project found that reed canary grass was by far the most suitable bioenergy crop for brownfield sites, growing on a range of soil types and planting conditions. Reed canary grass only required 18 months to mature, and could then be harvested every year. The yield was equivalent to around 5 tonnes of dry biomass annually per hectare. The fuel was of good quality, but contained 5-12% more ash than traditional wood fuels, so would be suitable for making pellets for commercial or industrial biomass heating or power systems. Although the other crops struggled to produce impressive yields, all sites were visibly greener with abundant weeds and wild flowers, providing natural habitat for bees, other insects and nesting birds. Transferring this project’s approach across Europe’s brownfield sites would bring tremendous benefits in terms of green-waste recycling, management of contaminated soils, and habitat and species biodiversity. It could also supply 2-4 GW of electrical power and three times as much heat without displacing food production and while providing aesthetic and health improvements for communities around brownfields. Further information on the project can be found in the project's layman report (see "Read more" section).