Mr Hughes said he managed to turn around some of the people who advanced the pro-drilling arguments of jobs and economic development.
He highlighted the risks of drilling company Anadarko operating at sea depths of 1.6km, compared with the Taranaki's offshore wells where the depths were about 125 metres.
"The industry itself says it is at the frontiers of technology."
Mr Hughes said the Greens would focus on clean energy if they formed part of the Government this year. He highlighted a PricewaterhouseCoopers report, which said the economic opportunities of using clean energy totalled $20 billion a year.
Although the issue was not defined by the generations, he had noticed opposition to deep sea drilling among many young people, and women in particular. Mr Hughes said young people had more opportunities to get into the environment and protect what they loved.
"Young people using technology have a different mindset for economic development."
He said older people who grew up watching Beverly Hillbillies tended to see oil as an easy way to achieve riches, whereas the Greens stressed the impact on fishing and tourism from an oil spill, and the subsidies and tax breaks offered by the Government to multinational drilling companies.
He said New Zealand had the fourth lowest tax and royalty rate in the world and that all the profits would flow offshore.
"The benefits are massively exaggerated."