Unless we switch to cleaner electricity production, we're only moving our pollution problems back up the line, says Dr Claire O'Connell
It's easy to feel a little bit smug when driving a hybrid car around a city. Compared with its gas-guzzling cousins, a hybrid's fuel efficiency saves a packet on the forecourt and slashes carbon emissions.
And the next generation of hybrids will aim to go a step further: plug-ins that charge from the electricity mains overnight can pull back even further on petrol and diesel usage.
But before we get too self-satisfied, let's stop and think about where that electricity comes from. In Ireland, the bulk of our electricity is generated from fossil fuels, which contributes to greenhouse gas emissions. So, unless we switch to cleaner electricity production, plug-in hybrids could simply push the emissions issue back up the line.
Discussions in Ireland to solve the problem revolve around using sustainable sources of energy like wind, with the bar set at generating one-third of our electricity from wind by 2020.
But what about other clean energy sources? Last weekend, the Taoiseach Bertie Ahern rejected nuclear power as an option for addressing global warming. But as our transport needs grow, can we afford to ignore the elephant in the middle of the room that is nuclear energy? Might we need to overcome our national aversion to all things nuclear in order to keep our cars moving in the future?
Increases in private car ownership and average engine size have pushed up Ireland's transport-related carbon emissions in the past 15 years, according to David Taylor, chief executive of Sustainable Energy Ireland (SEI), which wants to improve our energy efficiency while promoting renewable sources.
SEI sees plug-in hybrid cars as part of the solution and wants to pilot them here within a few years. Plug-ins could draw off surplus wind-generated electricity supply at night, then use it during the day for transport, displacing what used to be a fossil-fuel heavy activity, says Taylor.
"There's no doubt that we are at the beginning of a transition from a fossil-fuel-dominated economy to one that moves much more strongly towards renewable sources," he adds, noting that the time-frame for a renewables-dominated economy is around 2050.
But while SEI is keen to promote wind as a clean source of energy, the prospect of using nuclear power to generate electricity draws less comment.
"What technology you choose depends a lot on society's capacity to control and manage it. The Irish perspective on nuclear is that there are safety and proliferation downsides to it that are very hard to address now," says Taylor.
Safety issues around nuclear fission reactors include long-lived radioactive waste and the risk of "thermal runaway" in the reaction leading to an explosion. "It's a risk, but it's not a huge risk, and to some people it might be unacceptable," says physicist Dr Mike Hopkins from Dublin City University (DCU).
He argues that rather than ignoring the elephant in the middle of the room on the nuclear energy question, we should widen our view on the issue. "The risk to the planet from the burning of fossil fuels far exceeds any risks from nuclear radiation," he says. "I think not to be aware of the opportunities, to just bury your head in the sand and ignore it, is not a good policy."
Hopkins, a team leader at DCU with an interest in sustainable energy, is researching another potentially safer source of nuclear energy: fusion. Unlike fission, which blasts heavy atoms apart, fusion pushes isotopes of hydrogen together at extremely high temperatures, forcing them to fuse and release energy and helium.
"It's exactly the process that heats the sun," explains Hopkins, adding that in nuclear fusion, there's little reliance on carbon, no greenhouse-gas emissions, no risk of explosion and radioactive waste is vastly reduced.
However, recreating a controlled, burning sun on earth is no easy task and scientists have been working on the physics and engineering of nuclear fusion for half a century, with substantial progress in recent years. DCU will link into the €10 billion international ITER experimental fusion reactor currently being set up in France, and the hope is that by 2050, commercial nuclear fusion reactors will be a clean source of electrical energy, which in turn can sustain transport.
But despite what you may have seen in Back to the Future, don't go betting on a car being powered directly by nuclear energy just yet.