Key Points:

A supermarket chain is hoping a brighter alternative to the reusable green shopping bag will remind people to bring their bags to the supermarket.

Australian-owned Progressive Enterprises, which operates the Foodtown, Countdown and Woolworths supermarket chains, unveiled an "eco" bag by New Zealand designer Trelise Cooper yesterday at its Quay Street Foodtown store.

Ms Cooper said the Chinese-made, polypropylene bags - which sport roses and a red heart - were for women and "confident" men who wanted to do their bit to reduce waste.

The supermarket giant is hoping the eye-catching pink design will remind people to bring their reusable bags when they do their shopping.

Progressive has sold nearly 1.5 million reusable shopping bags since it introduced the green version in December 2003.

In the past year, the supermarket chain used nearly 29 million fewer plastic bags than the year before. But getting shoppers to remember their reusable bags has been a challenge.

"We sell hundreds of those green bags, but the issue is getting people to bring them back," said general manager of supermarket operations Dave Chambers.

He couldn't tell the Herald how many times a shopper would need to re-use one of the polypropylene bags to have less effect on the environment than using traditional plastic bags.

"We do know that hundreds of millions of plastic bags are given away in New Zealand each year and we are trying to reduce that."

A 2002 study by the Australian Department of Environment and Heritage found reusable polypropylene grocery bags generated about a third of the greenhouse gases used to make single-use plastic bags.

The study estimated households using plastic grocery bags would get through 520 bags a year, or 10 bags a week.

Under the voluntary New Zealand Packaging Accord, retailers have a goal of reducing plastic bag use by 20 per cent by 2009.

But packaging council executive director Paul Curtis said the focus of the 2004 accord was not environmental sustainability.

"Really the intention of the accord is to reduce waste to landfill. We weren't thinking about wider sustainability issues like climate change at the time."

And as far as landfill waste was concerned, Mr Curtis said it was important to keep plastic bags in perspective. He said 0.2 per cent of landfill waste was from plastic bags, while 40 per cent was organic waste.

The latest reusable bag design was Cooper's second attempt - she told the Herald she had redesigned the bag after representatives of Progressive said the original design was not "Trelise" enough.

"That's how we ended up with this very pink design."

Cooper is now working on a reusable grocery bag for men, as well as a reusable bag for her own store.

In the meantime, male shoppers and the budget-conscious can hang on to their green eco-bags, which retail for 99 cents, compared with $4.95 for the Trelise Cooper version.

GREEN TEST SCORE

How various types of grocery bags compare, based on a 2002 study by the Australian Department of Environment and Heritage comparing the greenhouse gases generated.

Plastic grocery bags for a year:

* 10 bags a week
* 520 bags a year
* Generates 6.08kg of greenhouse gases.

Paper grocery bags:

* 10 bags a week
* 520 bags a year
* Generates 11.8kg of greenhouse gases.

Reusable polypropylene bags:

* Four bags, used twice a week, would last two years
* Generates less than 2kg of greenhouse gases.

Large, reusable woven textile plastic bags:

* Generate 0.628kg of greenhouse gases.

(Based on a household carrying 70 grocery items home per week.)