In a press release announcing its “Green” efforts, Lake Forest’s Western Digital buried the news that it now has a 1-terabyte hard drive.

No specifics are mentioned in the press release, but WD just verified that this is indeed a “single (four platter) drive. It is our first 1 TB drive,” said Heather Skinner, a WD spokesperson. It ships THIS MONTH! It will first appear in an external MyBook hard drive and next month, will be available as an internal desktop drive.

This puts Western Digital back into the game, which was trailing more than a year behind largest rival Seagate Technology with a 750-GB drive. While Hitachi announced the first 1-TB drive in January, Seagate just got around to its first terabyte drive last month. Maybe that’s why Western Digital didn’t make a big fuss about this.

Now back to its GreenPower effort, Western Digital is calling its line of external and internal hard drives “environmentally friendly,” because they “save up to 40 percent in hard-drive power consumption, or as much as $10 per drive per year.”

Technically, WD’s new drives consume 5 watts less than the typical 1 TB drive (which uses 13.5 watts). And it reduces CO2 emission by 60 kilograms per drive per year.

To qualify as an Energy Star 4.0 computing system, the company needed to minimize its carbon footprint and offer savings in electricity costs. While saving $10 a year doesn’t sound like much, WD points out that this could help a data center with 10,000 drives save $100,000 a year in energy costs plus reduce CO2 emission by 600 metric tons — the equivalent of taking almost 400 cars off the road for a year.

The first “GreenPower” drive is the WD Caviar GP, or the aforementioned 1 TB drive. GreenPower versions of enterprise and consumer-electronics drives will be available in the third quarter, which is now.

As for price, no specifics yet. Says Heather with WD: “The new 1TB drives will be in price parity to Hitachi’s 1 TB drive.”