Ariel wants to help buildings reduce energy consumption; Todor plans to open a new biodiesel plant; Sheridan hopes to create an international greentech network; and Poppy has her heart set on a business making insulation material out of waste.

All four have their great environmental business plans. But would they convince the four-strong Dragon's Den they were pitching to?

Dragon Keith Girling, businessman turned county councillor for Newark West, was impressed by the young Poppy Potter's concept but didn't spare her an inquisition with a barrage of questions.

"It's a good idea," he told her. "But have you looked at the insulation qualities of this material? Have you looked at how much you would need to insulate one house?

"Have you looked at it in terms of planning regulations for use in houses? If it had to be treated for hygiene reasons how much would it cost?"

Poppy had to admit that she didn't have the answers at the moment and would have to go away and do some research. But she admitted later that the questions were exactly what she had needed to take her business idea forward.

And that was exactly what the Dragon's Den session, held in Nottingham as part of BioCity's first Enviro-Entrepreneur School, was all about.

Designed to help aspiring environmental entrepreneurs turn their ideas into real businesses, the school put more than 20 delegates from across the UK through their paces in an intense three day "boot camp" tailored to the growing low-carbon business sector.

Delegates had the chance to meet established local environmental entrepreneurs at the launch of Nottinghamshire's new GreenTech Business Network.

And they were also involved in sessions led by industry professionals in subjects such as IP and patent law, business plans, marketing, PR, private investors and the art of pitching business proposals.

It was this last character-forming technique that was put to the test in the four culminating "friendly" Dragon's Den sessions.

There was one major difference between this and the TV series: there was no investment money on offer at the Nottingham Dragon's Den.

On the other hand, the 20 "dragons" were expected to ask hard questions about the viability of the commercial ideas presented to them.

This was certainly true of one "den" – actually a board room on BioCity's 1st floor – where Poppy and three fellow enviro-entrepreneurs pitched their ideas.

Across the table sat the four dragons: BioCity incubation manager Nick Gostick, Martin Boddy of Connect Midlands, Nottinghamshire County Councillor Keith Girling and Jo Derbyshire, operations manager of the University of Nottingham Innovation Park.

First up was Chilean architect Ariel Chiang, who used a laptop to help describe his proposal for a building energy monitoring service.

Next was Sheridan Chilvers, from Nottingham, who proposed to develop an international greentech network.

The third pitch came from Poppy Potter, followed by Bulgarian Todor Stanev, who had firm plans to establish a biodiesel business in Nottingham.

All finished, the dragons were left alone and after debate decided that Poppy Potter had given the best pitch of the four delegates.

Nick Gostick, who devised the school, added: "It's been an enthralling three days. For us, it's a solid foundation on which to run another environmental school next year."