Christopher Jones, Deputy Director General of the Commission's energy directorate, was speaking after the Commission recently presented its policy package for a clean energy transition in the EU that promises to cut CO2 emissions by at least 40 per cent before 2030.
The Commission's proposals also call for a 27 per cent share of renewables in energy provision by 2030.
The executive's 'winter package' is meant to underpin the EU's efforts to limit global temperature increase to 1.5°C, as agreed in Paris. By 2030, the EU has pledged to reduce carbon emissions by at least 40 per cent, increase the share of renewable energy to at least 27 per cent, and improve energy efficiency by at least 27 per cent.
But, speaking in Brussels, Jones cautioned of possible problems ahead in meeting the targets on renewables.
He told an audience of energy experts that subsidies for the renewable energy sector were "very expensive", costing some €50bn a year, and that there were still no legally binding targets for member states on the share of renewables, such as wind and solar, in the energy mix.
Limiting global temperature increase to 2°C will also require, he said, cutting CO2 emissions by some 80 to 90 per cent by 2030 compared with 1990 levels.
"Yes, we have to try and make renewables a more normal part of the electricity market but there are problems that need to be addressed," said Jones, who was a keynote speaker at a debate on EU energy, organised by the Wilfried Martens Centre and Antall Jozsef Knowledge Centre.
He added, "This is going to need a zero carbon system and technologies that are at least as competitive as fossil fuels. It could be argued that it is difficult to see how we will achieve this."
The veteran EU official went on, "Energy policy can be likened to a unicorn, in other words, a mythical beast. However, I believe that we are getting there."
Jones also said it would be necessary to make subsidies "more competitive" and eliminate "distortions in the energy market."
With the European Parliament in Strasbourg this week for the last session before Christmas, further comment on the winter package has come from MEPs, including, Peter Liese, the EPP group spokesperson on the environment committee, who underlined and welcomed the Commission's priority on energy efficiency.
He said, "Energy efficiency is the most cost-effective way to reduce greenhouse gas emissions. The increased target of 30 per cent will help us achieve our commitments under the Paris climate agreement. Moreover, energy efficiency initiatives will create a lot of jobs in the European Union."
Bas Eickhout, Greens/EFA spokesperson for environment, was less impressed, saying, "While Commission President Jean-Claude Juncker declared his intention to make the EU world number one on renewables, the level of ambition (27 per cent) is critically low. This target would result in halving the current deployment rate of renewables."
Another Greens MEP, Claude Turmes, the group spokesperson for energy, said, "Beneath a small step forward on energy efficiency and some good language on increasing the role of energy citizens, this package is above all a major step back on renewables.
"Weak ambition, weak governance, removal of priority access and lack of clarity about future support schemes will not allow the EU to become world number one in renewable energy."
The business community has also given its reaction to the raft of new energy proposals, with Markus Beyrer, Director of BusinessEurope, saying, "We support the Commission's plan to further strengthen the functioning of the EU's power market.
"The full integration of renewable electricity is essential. It is positive to put all energy sources on equal footing with clear responsibilities. We should get rid of distortions in the energy market caused by subsidies and decrease the energy costs for consumers."