The Madison biofuels firm Virent Energy Systems Inc. said Monday it has developed a process to help the bottling industry make plastic bottles without petroleum.

The company said its chemical engineers have been able to produce paraxylene, also known as PX, from 100% renewable plant sugars. When combined with existing technology, this can allow manufacturers to offer 100% natural plant-based plastic bottles and packaging.

In a statement, Lee Edwards, Virent chief executive, said the work represents a "significant achievement for global leaders in consumer products. Our plant-based PX paves the way for 100% sustainable, recyclable products and packaging with complete freedom from crude oil."

The technology uses a chemical process that converts plant-based sugars into molecules that Virent says are identical to those made from petroleum.

Virent said it's working with potential partners and customers to explore large-scale commercial options to augment its 10,000-gallon-per-year demonstration plant in Madison.

Last week, the company announced a milestone in the liquid fuels arena — its work in conjunction with the National Advanced Biofuels Consortium to produce biogasoline from feedstocks that come from nonfood crops.