The proliferation of renewable portfolio standards (RPSs) in states across the US has created a market for trading in renewable energy credits (RECs). However, a lack of uniformity in RPS design means this is a highly fragmented market, with those involved in the sector struggling to trade across state lines.

A federally mandated RPS could tie all of these disparate state markets together. Although a nationwide standard is still some way off, any clues as to how such a scheme might be structured