By Rory Cellan-Jones
BBC News technology correspondent, Las Vegas
CES is the world's largest annual consumer technology trade show
The world's gadget makers have become more environmentally friendly but have some way to go before they can claim to be green.
That's the verdict of a report by Greenpeace launched at the Consumer Electronics Show (CES) in Las Vegas.
The pressure group collaborated with the electronics industry in a study which saw fifteen companies submit fifty of their most environmentally friendly brands for examination.
The products were marked on three main criteria - use of hazardous chemicals, power consumption and recycling.
The highest-scoring product was Lenovo's 24in (61cm) widescreen monitor, which scored 6.9 out of 10. The lowest scores were recorded by Acer, with 3.3 for its Veriton desktop computer.
Casey Harrell, toxics campaigner for Greenpeace, said progress had been made but there was room for improvement.
"We're not arguing any more about whether green is good - we're arguing about the definition of green and the pace at which we're getting there," he said.
The campaign group said six companies had refused to take part in the survey - Apple, Asus, Microsoft, Nintendo, Palm and Philips.
Greenpeace said it was disappointing that Apple had refused to cooperate for the second year running, especially since its new range of Macbooks could have scored well.
The Consumer Electronics Show's organisers are claiming that this year the environment is one of the biggest themes for the companies exhibiting here.
"Energy efficiency recycling and green technology is a central focus of the show," said Jason Oxman of the Consumer Electronics Association - the organiser of CES.
"Our research found more than 50% of consumers are taking green attributes into account when they buy a device and for television that's even higher," he said.
"89% said they would rather purchase a television that was energy efficient than one that wasn't."
The cavernous halls of the Las Vegas Convention Center are packed with power-hungry gadgets, and vast displays of television monitors, with companies competing to put on a lavish display.
But one corner is set aside for green products.
Under a banner reading "Towards a Sustainable Future", there are recyclable batteries, portable fuel cells, backpacks which collect solar-power so that you can recharge gadgets on the move - and a wooden radio.
That's on display on the stand of a business called Areaware, which also features a bicycle with solar-powered lights, low-energy lighting and other products which combine attractive design with sustainability.
Next to its stand is Freeplay, a British company which pioneered the wind-up radio.
It now has plenty more green innovations aimed at the developing world - from a solar-powered DAB radio to a crank-operated foetal heart rate monitor for use in places where access to power is tricky.
Richard Wharton of Freeplay and Noel Wiggins of Areaware agreed there was more focus on green products at CES this year, though Mr Wharton said it had started from a low base.
"This is our third year here, and it is much better," he said.
"Last year the green gadgets area was really small. This time they've put a lot of PR effort into it."
Actor Tom Hanks tried on one of the latest gadgets on display at CES
Mr Wiggins said there was growing consumer interest in greener gadgets, particularly among women: "Consumers are feeling a lot of guilt about the environment - and mothers tend to drive it because they worry about the next generation."
Mr Wharton said British retailers, from Marks and Spencer to the Dixons Stores Group, were now showing growing interest in green gadgets but needed to market them better.
"I think retailers have been guilty of making it unsexy - green products can be cool," he said.
Most of the exhibitors at CES are trying to persuade shoppers their gadgets offer something new and better than what was available last year.
Mr Wiggins says that approach is wrong.
"Consumers in America have a tendency to buy things and then throw them out," he said.
"You don't need to be chasing a new idea, a new feature all the time - that mindset needs to change. We need well-made, sustainable products that will last."
The ethos of the world's biggest gadget show may be changing but it is hard to see the organisers pushing the message that consumers should wait a while before buying that new computer or television.