Screen shot 2010-01-26 at 9.24.32 AMAcorn Energy, the publicly-traded energy holding company, has released preliminary earnings sowing a 51 percent jump in revenue from $20.7 million in 2008 to $31.3 million to 2009. Notably, these figures were buoyed by an 80 percent increase in revenue for its subsidiary CoaLogix, maker of clean coal technology.

That company, which specializes in filters that remove harmful agents like heavy metals and nitrogen oxides from coal-fired plant emissions, reported revenue of $18.1 million this year, up from $10.1 million in 2008 — indicating growing interest in clean coal initiatives other than carbon capture or sequestration. It was helped by $11.5 million in funding raised last April.

When we reported on CoaLogix at that time, a lot of readers objected to the concept of clean coal measures — arguing that more money and time should be poured into developing renewable sources of energy like solar and wind, rather than cleaning up fossil fuel sources. But clean coal companies don’t appear to be going anywhere. With coal remaining the U.S.’s most plentiful and cheapest source of energy, there’s no chance that the national power mix will drop it completely for decades to come. We might as well make it less damaging, clean coal supporters say.

Acorn Energy’s other holdings fall in different, niche areas of the green sector. DSIT Solutions uses sonar and acoustic technology to provide security to underwater energy installations. It also did well last year, with a 10 percent increase in revenue from $8.4 million in 2008 to $9.2 million in 2009. Its other primary subsidiary, Coreworx, maker of software used to manage energy construction projects like nuclear power plants or uranium mines, saw its revenue remain flat at $4 million.

Acorn also owns GridSense Systems, which provides Smart Grid tools to utilities to detect and manage electricity outings, monitor grid loads, run demand response programs, and increase energy efficiency.