Business Green: The state of California has formally adopted the strictest environmental regulations anywhere in the US last week, committing to a package of measures designed to cut emissions 15 per cent by 2020. Under the wide-ranging plans, the state will require utilities to generate a third of power from renewable sources by 2020 and will also introduce a raft of binding targets governing emissions from cars, oil refineries, buildings and landfill sites. The primary mechanism for …