At MetaEfficient I’ve been waiting for years to review some exciting green computers, and now finally in 2008, we’ve seen the introduction of some truly green PCs. Although the components of green PCs cost about 10% more than regular PCs, they retail for about the same price. You can jump ahead and see our list of the greenest PCs. Or you can read about the details of the green rating processes.

How do you judge the greenness of a computer? The two most important factors are power consumption, and the elimination of hazardous components inside the machine. Other factors such as the efficiency of the power supply, packaging and the manufacturer’s support for recycling programs are also important. Overall, there are a huge number of factors to assess, but thankfully there are now some eco-certifications that make it easier. The most important certifications are EPEAT (Electronic Products Environmental Assessment Tool), RoHS (Restriction of Hazardous Substances) and Energy Star 4.0. All three of these certifications are standardized, so they are more specific in their assessments than the marketing claims or green initiatives of the past. Here’s a brief description of the certifications:

The EPEAT system is currently the most comprehensive verification of a computer’s environmental attributes. EPEAT was created by a consortium of electronics manufacturers, and partially funded by the U.S. Environmental Protection Agency. EPEAT evaluates computer desktops, laptops, and monitors based on 51 environmental criteria including Energy Star compliance. If a computer is awarded the EPEAT Gold rating, it is one of the greenest out there. You can see a list of all the desktop computers that achieved a Gold EPEAT rating here. A summary of the criteria can be found here
The new EnergyStar 4.0 certification assesses the power consumption of PCs, but it doesn’t cover other criteria like toxicity. To comply with the new Energy Star 4.0 standard, a desktop PC must use under 50W in idle mode and 4W when asleep.
The RoHS (Restriction of Hazardous Substances) directive bans from the EU market any new electrical and electronic equipment containing more than mandated maximum levels of lead, cadmium, mercury, hexavalent chromium, and two flame retardants. RoHS covers everything in a computer except for the batteries, which are regulated separately.

Another useful guide is Greenpeace’s Guide To Greener Electronics which was recently updated in June. The companies that scored the highest ratings from Greenpeace were Sony Ericsson, Sony, Nokia and Dell.

Here’s our round-up of this year’s greenest personal computers:

Dell’s Studio Hybrid PC

This month Dell introduced what it calls its greenest desktop computer. The new Studio Hybrid is not only Dell’s smallest-sized desktop, it’s also its most energy-efficient. The system uses only 1 watt of power when off or in hibernate mode, a frugal 26W while sitting idle, and 44W when the system is fully taxed, according to PC Magazine. This makes it one of the most energy efficient PCs available — it uses only a couple more watts than the power-sipping Mac mini. Like the Mac mini, the Hybrid uses an external power brick instead of an internal power supply.

The Hybrid also has Energy Star 4.0 certification and a system recycling kit that allows you easily recycle the computer at the end of it’s life. Disappointingly, it only gets a Silver rating from EPEAT, rather than a Gold.

The Studio Hybrid is packaged in 95% recyclable materials, and ships with 75% less printed documentation. You can order an optional exterior sleeve made out of bamboo (more sustainable than plastic, although it costs an extra $130).

The Studio Hybrid doesn’t come with many USB ports, but you can order an optional wireless keyboard and mouse for $50. The base Studio Hybrid configuration starts at just $499 (monitor not included). More tricked-out systems run up to $1,329 or more, depending on what options you order. The Studio Hybrid is available from Dell’s web site now, and will be for sale at select retailers in the coming months.

Link: Dell’s Studio Hybrid

Lenovo’s ThinkCentre M57/M57p

Lenovo’s ThinkCentre M57p is a very green corporate PC with a no-frills “old school” design. This compact computer has Intel’s latest 45-nanometer CPU architecture (code-named “Wolfdale”), yet the whole system consumes only about 58 watts of power at peak. It also has all the important green certifications: EPEAT Gold, RoHS and Energy Star 4.0. According to Lenovo, this machine also contains up 90% re-usable and recyclable materials and the packaging is 90% recyclable.

The system’s dual-layer DVD burner and internal 160GB hard drive are full desktop size, so they’re easy to replace with standard (and cheaper) parts in case something goes bad. Since the M57p is housed in a small-form-factor case, it has no internal expansion room to speak of, so you’ll have to plug an external USB hard drive or large-capacity USB thumb drives into one of the four available USB ports for more drive space. The system also is limited to integrated Intel GMA 3100 graphics. On the plus side, there are both VGA and DVI ports for either type of monitor, and the system does support dual monitors (one VGA and one DVI).

Link: Lenovo

It’s available at Amazon

Apple Mac mini

The Apple Mac mini is widely known for its iconic design, but it also has a number of green credentials that earn it a place on our list here. When it was introduced, the mini set a new standard for energy efficiency. It’s still the most energy efficient desktop computer available — it consumes just 20-28 watts on average.

Tom’s Hardware reports:

During testing, our Mac min was able to shine in this respect, drawing a mere 20 watts of power; during DVD playback, this rose to only 28 W. In contrast, the power requirements of current Intel-based PC systems is anything but reasonable – under comparable conditions, these power-hungry machines draw up to 160 watts.

According to Apple, the mini is about 90 percent recyclable. It received a Silver EPEAT rating.

The Mac mini has been considered a budget Mac (prices start $600), but now that it’s equipped with a Core 2 Duo processor, it’s as powerful as a larger desktop.

Link: Apple Mac mini

It’s available from Amazon.

Zonbu Desktop Mini

The Zonbu Desktop Mini is a Linux-based, minimalist computer that contains no hard drive, instead, in the spirit of “network computing” everything is stored online. After paying $99 or $299 for the computer itself, you the Zonbu owner can subscribe for the online storage service (via Amazon’s S3 network) for $12.95 a month for two years (or $149 for a yearly subscription).

The absence of a hard drive means the Zonbu is silent, and consumes just 11 watts when running (8 watts in standby mode). It has a number of other green attributes including EPEAT Gold, RoHS and Energy Star 4.0 certifications. The manufacturer also has a recycling take-back system, and they use minimal, recycled packaging for the computer.

Link: Zonbu Desktop Mini

CherryPal PC

The CherryPal is a similar to the Zonbu Desktop Mini — it has no moving parts, and everything is stored online, including its applications. The CherryPal is designed to be used for only need basic computing and Web browsing. The machines itself measures just 1.3 x 5.8 x 4.2 inches, and it has a Freescale processsor with 256MB of RAM, a 4GB solid state drive, 802.11g Wi-Fi, a Firefox browser, and a Debian Linux operating system. Applications likes OpenOffice, iTunes (including iTunes Store support), and other CherryPal-branded apps will be accessible from the desktop. Since everything is administered by CherryPal, malware protection, antivirus efforts, and software upgrades are done automatically.

CherryPal claims that this is the greenest and most affordable PC, since it consumes just 2 watts of power, uses 80 percent fewer components (than an average desktop), and can last a decade or longer. The CherryPal’s price is $249, a bit cheaper than the $299 Zonbu. (The Zonbu was originally available subsidized with a contract for $99.)

There is no contract for the CherryPal, nor any monthly fees, and 50GB of lifetime (or at least the lifetime of the company) storage is included.