* Renewable energy drive could influence September vote
* Merkel chose doughty chief whip for vital ministry a year ago
* Altmaier has not reconciled industry and green lobby
Chancellor Angela Merkel appointed him for his charm and political skill as marshal of her vision of a 'green revolution' in Europe's biggest power market. A year on, Peter Altmaier finds himself spurned by many environmentalists, disdained by industry and viewed cooly by a public wary of the costs.
Now, the chancellor herself seems to be turning her back on him, an increasingly isolated figure, as September polls near.
Merkel's ambitious goal of weaning Germany off fossil fuels and phasing out nuclear power is widely viewed as her most significant domestic policy. Implementation is a mammoth task and means taking decisions unpopular either with Germany's powerful industry or its strong green lobby.
Altmaier, who had impressed Merkel in quashing turmoil in her conservative party over euro zone bailouts, has become a lightning rod for dissatisfaction over the costs of an energy policy long central to her domestic agenda.
Merkel has maintained a high personal popularity rating, far higher than her party's, and kept the peace in her centre-right coalition; but in so doing she has made his job harder, staying silent on some of his more controversial, but much-needed ideas such as reining in subsidies for renewables.
"He's been remarkably active and good at focusing on the message but he's had difficulty building the bridges he wanted to. Not everybody is behind Peter Altmaier," said Miranda Schreurs, member of a government environment advisory panel.
It is not for want of trying. Altmaier is an accomplished social networker and lover of good German food, banging heads together over home-made meals at his roomy flat in West Berlin.
"Food can open doors," the Environment Minister, who is especially fond of the Saarland speciality of dumplings stuffed with liver sausage, once said.
"The best ideas often emerge over a good meal."
Germany is seen by many around the world as a green energy pioneer. Not known for its sunshine, it nonetheless hosts more than a third of the world's photovoltaic capacity thanks to generous subsidies.
Last year, some 22 percent of German power came from wind, photovoltaic, biomass and other renewables. The aim is for 80 percent of German power to be generated from renewables by 2050.
In a cabinet short on charisma, Altmaier, 54, stands out with his easy manner and very publicly stated fondness for the kitchen. He boasts a Twitter following of 41,000.
But for all his political astutness, enthusiasm and diligence, critics point to a patchy track record.
Under his watch, German carbon dioxide emissions have risen for the first time in more than two decades. He has cast doubt on energy savings goals and stunned experts by saying the shift to renewables may cost 1 trillion euros, far more than expected.
Merkel offered him little public support for ultimately rejected plans to curb rises in household power bills and withheld her blessing when he pressed EU proposals to prop up the Emissions Trading Scheme (ETS), a tool to fight climate change.
"'Interesting guy, great show, no results' is how I'd sum up Altmaier's first year in office," said opposition Social Democrat (SPD) environment expert Ulrich Kelber.
It was, Kelber said, not entirely his fault.
"His main task seems to be ...ensuring peace in Merkel's (centre-right) coalition. Merkel hasn't helped him. She's silent when it comes to decisions or coordination," he added.
Merkel's business-friendly Free Democrat (FDP) coalition partners oppose much of Altmaier's vision. They seek a much deeper reform of green subsidies than he has proposed.
Controlling as they do the Economy Ministry, the FDP shares the energy portfolio and, accordingly, makes its views felt. Scarcely a recipe for harmony.
The environment ministry declined to talk to Reuters for this story but Altmaier said on Twitter his track record was 'super'.
He cited legislation on cuts to photovoltaic incentives, shutting a nuclear waste storage site in northern Germany and agreeing a framework for a search for a new nuclear dump.
"Many regulations, agreements with industry and associations on the green economy, biodiversity, energy efficiency and saving power. Most importantly, the environment and energy are once again top of the agenda!" he wrote on Twitter.
'Top of the agenda' may be something of an exaggeration at a time of economic uncertainty in Germany and across the eurozone.
"For many people the question is how much do I pay? That could well be an issue in the election," said Schreurs.
Polls show that while a majority of Germans back the energy shift, they don't want to pay for it. Last year a surcharge on household power bills to pay for the switch to renewables rose 47 percent and it is set to jump again before the election - something that may fall to Altmaier's cost.
"Some people in the branch are very disappointed and say he betrayed the cause," said Hermann Falk, head of the BEE group for renewable energy, adding he would not go that far himself.
Altmaier's congenial manner makes him popular on chat shows and he cuts a widely recognised figure on the political stage.
"He realised the energy switch is a wide-reaching topic," Falk told Reuters. "He has the chance to have an impact, strengthen his own power base and make his career." .
However, Altmaier ranked only 14th among politicians in a TNS poll in March which showed only 34 percent of Germans thought he should have an important role in future. That, though, in a party dominated by a chancellor who has brooked little rivalry in the leadership.
People who know him say he would like to keep his job if as expected Merkel is re-elected; even if the entertaining that goes with it proves bad for his girth.
"I like to start with a healthy breakfast - blueberries and yoghurt," he told Bild daily. "But in Berlin there's always the temptation to grab a chocolate bar or sausage with curry sauce."