There's the much-criticised battery hen egg, and then the pricier organic and free-range varieties. But for the truly ethically committed, how about the carbon-neutral egg, laid in what has been billed as the world's most environmentally friendly farm? Dutch stores are now selling so-called Kipster eggs" laid at a shiny new farm. The intention is to rethink the place of animals in the food chain, according to Ruud Zanders, the poultry farmer and university lecturer behind the farm. Mass-producing farms, even those that have moved on from cages, produce extremely cheap eggs at a heavy cost to the environment and the welfare of the animals laying them. The cost-cutting model is blamed by many for the regular food scares in northern Europe, including the recent enforced destruction of millions of eggs due to contamination by the toxic insecticide fipronil. The organic and free-range varieties, where farmers prioritise the welfare of the chickens, often sell at a higher price - but again at a cost to the wider environment, feeding the chickens expensive imported corn that could be better used to feed people. "It makes no sense for us to be competing with animals for food," Zanders said. "And 70% of the carbon footprint in eggs is accounted for by the feed for the chickens." Zanders's selling point is that his farm has the highest welfare standards - as endorsed by Dutch animal activist group Animals Awake - matched with the lowest possible environmental cost. By using waste food as feed, the farm is ... cutting deeply into its carbon footprint.