- Funding streams vary across think tanks. Sometimes you get a grant or contract with a particular product specified: a report, a journal article, etc. That's easy. You disclose who gave you the money.
- Sometimes a philanthropic organization will fund a broad research agenda (I published a few things out of the "Low Income Working Families Project" at the Urban Institute, for example). I never once contacted the philanthropic organization - only the people running the effort at the Urban Institute. I never competed for their money. I'm not even sure they knew what I was writing until after it was published. But again that's easy - you disclose the organization that funded the agenda.
- Some organizations (the Urban Institute did not work this way but groups like EPI or Brookings do, as far as I know) fund research out of a big research budget. Again - researchers probably don't have direct contact with funding organizations and the funding organizations may not even see the product. In this case, my view is that it's fine to just note your research organization (i.e. - Brookings, EPI) and only note funders if (1.) the money for your research had a very specific funding stream, or (2.) if your research is very relevant to a particular donor, particularly a large donor (this has been frustrating for my co-authors and I recently... we've been sparring with some people at Brookings, which gets a lot of money from the Gates Foundation for post-secondary education research. Gates, of course, is one of the most prominent voices supporting H-1B visas. They really oughta mention that Brookings gets money from the Gates foundation, but they don't).
I assume the Institute for Energy Research falls under the third category, so it's a little less clear what makes the most sense. But come on - if you're talking about carbon taxes and you get any appreciable amount of money from Koch or Exxon - industries that will be directly affected by carbon taxes - it oughta be mentioned somewhere.
But as I noted in the last post, exactly how and what you disclose is debatable and largely depends on the structure of the organization.