This is the weekly post from Bruce Nilles, director of Sierra Club’s Beyond Coal Campaign . Last week when we hit the 100th coal-fired plant abandoned or prevented in the U.S., someone asked me, “What’s next?” My answer came quickly: “ It’s time to stop the next 100 .” And so with that we’ve just launched a new campaign to persuade the Blackstone Group to invest in clean energy instead of dirty coa l. One of the 10 largest private equity firms, Blackstone now has more proposed coal