A small community skating rink that was once in danger of folding is working on a long-term plan to eliminate its biggest single expense – its energy bill – by becoming what its leaders believe would be the country’s first with no costs for electricity or heating fuel. The plan includes upgrading the existing equipment at Woodstock’s Union Arena for efficiency, finding ways to reuse some of the heat generated by the power-sucking compressors used to make ice and, finally, buying solar panels that will be erected elsewhere.