“The Boston-based Acadia Center said the decline in prices was due to an estimated oversupply of 130 million allowances and continued low carbon emissions. It said emissions reductions have outpaced the RGGI emissions cap, lowering demand and inflating the supply of allowances.

“The RGGI states should seek to improve these market conditions through the current program review by establishing ambitious cap levels through 2030, reforming the cost containment reserve and conducting additional adjustments for banked allowances,” Jordan Stutt, an Acadia policy analyst, told Bloomberg BNA in an e-mail.”