The coalition government had "created a much more expensive alternative" by rejecting plans for a levy on coal at their environment summit on Wednesday night, Hendricks wrote.
The electricity sector was only being asked to make a small part of the 22 million tonnes of annual CO2 emissions savings that were needed each year, Hendricks said.
"Everyone involved must understand that the coal power sector can't conclude from this that in the future it will be spared from its obligation to protect the climate – quite the opposite!"
Leaders from Chancellor Angela Merkel's Christian Democratic Union (CDU), their Bavarian sister party the Christian Social Union (CSU) and the Social Democratic Party (SPD) gathered on Wednesday night for the latest round of environment talks.
Although they agreed to phase out brown coal power plants, they rejected plans to introduce a coal levy on electricity producers to reduce CO2 emissions.
Instead, the government will try and foster a better mix of electricity generation methods – a plan which will cost taxpayers around €10 billion.
Hendricks criticized the "many polemics and not a little horseplay" in the battle over the coal tax.
Opponents had claimed that trying to cut CO2 emissions by 22 million tonnes would endanger 100,000 jobs in Germany.
"For me, such declarations are the expression of political incompetence and denial of the future," she wrote.
Neither did Hendricks shy away from attacking the Chancellor herself.
"You can't announce the climate-neutral world economy [at the G7 meeting] in Elmau and at the same time act as if all that doesn't count for the coal regions of our country," she wrote.
G7 leaders agreed at a June summit in Elmau, Bavaria to gradually reduce their countries' dependence on oil, gas and coal.
The whole world must reduce emissions of CO2 and other greenhouse gases to have a hope of keeping global warming below two degrees Celsius, a threshold beyond which scientists say there would be catastrophic consequences.