This would be the SETI's Colossus telescope project, that aims to build a high-resolution, multiple-mirror instrument with ability to directly image the heat generated by other civilizations on planets orbiting stars near us:
Artist's impression of the proposed SETI's Colossus Telescope (Credit: Innovative Optics/Colossus Corporation)
As Earth-like civilizations evolve, they use more power. For example,
in Roman times, we estimate Ω [the ratio of a civilization’s power production to the amount of solar power it receives] was about 1/1000 what it is today.
Humans’ global power consumption is growing by about 2.5 percent per
year, even though the world’s population is growing at less than half
this rate. In contrast, our knowledge base (the combined total of all
recorded information) doubles in just two years. As cultures advance,
their information content also must grow, and the power required to
manipulate this knowledge eventually dominates a civilization’s total
Using a sensitive coronagraph to remove scattered light that would
obscure an exoplanet, Colossus would be able to find hundreds of
Earth-sized or larger planets in the habitable zone including any
civilizations on their surfaces.
Source: Paul Gilster for Centauri Dreams quoting Jeff Kuhn (University of Hawaii), Svetlana V. Berdyugina (University of Freiburg), David Halliday (Dynamic Structures, Ltd., in British Columbia), and Caisey Harlingten (Searchlight Observatory Network, Norwich, England)
Here is a Jeff Kuhn's, Institute for Astronomy, University of Hawaii, talk on The Colossus Telescope and the search for ET, and a quite descriptive blog post by Brian Wang on Technology for 77 meter primary mirror ground based telescope exists today and it could survey earth sized exoplanets out to 60 light years advocating the project from a technology perspective.
A bit more can also be read on the Innovative Optics Ltd. web pages, that are sadly under construction, but they do give a hint that an article about it was written in June 2013 edition of the Astronomy Magazine, titled How to find ET with infrared light (PDF), by Jeff R Kuhn, Svetlana V Berdyugina, David Halliday, Caisey Harlingten. A nice digest is also available in this Centauri Dreams blog post.