The government has dropped plans to raise the UK's renewable energy target after the Committee on Climate Change (CCC) warned it would be infeasible or at least lead to "rapidly escalating costs".
Energy secretary Chris Huhne blamed "the legacy inherited by the coalition" for making raising the target unrealistic.
In their programme for government, the coalition parties committed to go beyond the current target of 15% of energy to come from renewables by 2020 (ENDS Report, May 2010).
Mr Huhne's party, the Liberal Democrats, drove this agreement. Its election manifesto pledged to get 40% of the UK's electricity from renewables by 2020 – up from the 30% needed to meet the current target (ENDS Report, April 2010).
However, the coalition's pledge was subject to advice from the CCC, and this week it wrote to the government recommending against any increase in the target.
"The focus should be on implementation," it said, with some significant delivery issues still needing to be addressed "as a matter of urgency". These include the low planning approval rate for onshore wind and uncertainties around the future of the Renewables Obligation.
The government may have to actually lower its ambitions on renewable heat and biofuels, the committee said.
Government modelling assumes 12% of the UK's heat supply will come from renewables in 2020, but the committee said the "costs… could be very expensive at the margin" as more solar thermal systems have to be installed. "A slightly lower level of ambition may be more appropriate."
The UK has also said 10% of transport fuels will be biofuels in 2020, but the committee said the objective should be reduced to 8% "unless new evidence shows that [a higher level] can be achieved sustainably".
The government should focus on reducing energy demand to compensate for these changes, it added.
The Renewable Energy Association reacted to the CCC's letter positively, although it said reducing the biofuels target would be illegal. Under the EU Renewable Energy Directive 10% of road transport fuels has to come from renewables by 2020, although the commission has committed to reviewing this in 2014 due to concerns over the sustainability of biofuels.