Greenpeace has another tech giant within its sights as it took aim at Twitter this week, setting up outside the company’s San Francisco headquarters for a protest that included a green Twitter bird and a sign that read “Make our tweets green.” In Greenpeace’s annual report, in which the company grades Silicon Valley companies in terms of their use of clean power, general energy efficiency, and transparency about their energy behavior, Twitter scored a triple F. That’s in contrast to companies like Apple and Facebook, which were head of the class.

Greenpeace’s efforts to shame big IT into sourcing clean power and investing in energy efficiency would be comical if it weren’t for the fact that the efforts seem to have worked so well in the past. It’s “unfriend coal” campaign played a role in Facebook moving to clean power sources for its data centers. And I believe its pressure on Apple was part of the reason Apple’s North Carolina data center is now adorned with a solar farm and fuel cells.

Will Twitter, and Amazon, which also got bad scores, change this go around? I do think that the negative PR could be an issue for a consumer facing brand like Twitter, perhaps less for Amazon Web Services. Also, there’s a perception issue within Silicon Valley where environmental concerns rank high and being able to recruit talented workers to a company perceived as being less than green is not ideal for a growing company like Twitter. My bet is that it may take a couple years but we’ll see some changes at Twitter.