(Reuters) - Donald Trump, a big supporter of the U.S. oil, gas and coal industries, has promised to get to work quickly after being sworn in as president of the United States, raising expectations that he will sign a slew of executive orders. Here are some of the executive actions and other maneuvers that could come quickly, related to energy, the environment and climate change: Trump, a Republican, has promised to kill Democratic predecessor Barack Obama’s Clean Power Plan, which requires states to cut carbon dioxide emissions from power plants. He has a few options to do so, some simpler than others. The plan is being challenged by 27 of the 50 states in court, so one option is to order the Justice Department to stop defending it – effectively giving the plaintiffs a win. Trump could also seek a “voluntary remand” asking the court to send the rule back to the Environmental Protection Agency for review. The problem is that attorneys general from states like New York and California, as well as environmental groups, would likely step into the gap and defend the rule. Another possibility would be to order the EPA not to enforce the rule. That, too, could open the door to lawsuits.  A third option would be for Trump’s administration to try to issue a new regulation “withdrawing” the Clean Power Plan, even if it is upheld in the courts, according to the American Energy Alliance, an industry group that helped advise Trump’s energy transition team. That move may not be a fast one. The Clean Power Plan, finalized in 2015, was the centerpiece of Obama’s broader climate change strategy. The Waters of the U.S. rule, which seeks to clarify which waterways fall under federal environmental protection, has been mentioned repeatedly by Trump as a regulation he hopes to overturn. The rule is also being challenged in court. Legal experts say Trump’s options here are similar, and one of the most elegant ways to overturn the rule would be through a voluntary remand, a legal vehicle that would ask the court to return the rule to the EPA for review. That would then give Trump’s administration the ability to kill or revise the rule, but could also draw some lawsuits from Democratic attorneys general and environmental groups that want the rule preserved.  Trump has promised to ask TransCanada Corp (TRP.TO) to resubmit its application to build the Keystone XL pipeline, a project to pipe more Canadian oil sands crude into the United States that was rejected by the Obama administration after years of environmental lobbying against it. While the invitation to resubmit could come quickly, it is unclear whether TransCanada would seek to revive the project given that oil prices are far lower now than they were when the company initially pursued it.  Trump may also seek to issue an order to undo a guidance issued last August by the White House Council on Environmental Quality that requires federal agencies to quantify greenhouse gas emissions and factor in impacts on climate change while evaluating projects like pipelines. The council had updated the decades-old National Environmental Policy Act to include the greenhouse gas update. Trump could sign an executive order approving the Dakota Access Pipeline in North Dakota, or order the acting secretary of the army to approve the project, according to Brigham McCown, former head of the U.S. Pipeline and Hazardous Materials Safety Administration under President George W. Bush. However, such a move would be highly unpopular among pipeline opponents who have camped out at the construction site for months. Leaders from the Standing Rock Sioux tribe, which led the protests over worries the pipeline would threaten water quality, have vowed to challenge any executive action. The pipeline is owned by Energy Transfer Partners LP (ETP.N).  One little-known tool used by the Obama administration to support its regulations curbing carbon emissions is the “Social Cost of Carbon,” a calculation made by a panel of technical experts to place a dollar value on the public harm caused by carbon dioxide emissions. The calculation is used in the rule-making cost/benefit analysis.  The current cost of carbon is put at $36 per tonne, which will rise to $50 by 2030. The American Energy Alliance believes that Trump could immediately order government agencies to end the use of the Social Cost of Carbon, which could help it unravel a number of Obama’s other anti-carbon regulations. Trump could immediately lift the Department of Interior’s moratorium on coal leasing on federal land, which the department enacted last year as it sought to review the program and evaluate whether the government adequately priced the value of coal extracted from public land on behalf of the taxpayer. Lifting the moratorium would improve industry access to vast coal deposits remaining in the Powder River Basin. Reversing some of Obama’s more recent moves to put federal acreage off limits to drilling could be more complicated. Obama designated around 1.6 million acres of federal lands in Utah and Nevada as monuments, using a tough-to-overturn law called the Antiquities Act. He also permanently protected areas of the offshore Arctic and Atlantic using another law that legal experts say would be a challenge to overturn. The Obama administration finalized a couple of environmental regulations in its last weeks in office that are likely to be quickly overturned, including the Bureau of Land Management Methane Rule and the Streams Protection Act. Congressional leaders said they would target those rules under the Congressional Review Act, which allows lawmakers to use a simple majority vote to rescind a regulation within 60 legislative days of publication.  The methane rule limits methane emissions from energy installations on federal land, while the Streams Protection Act protects waterways from coal mining runoff. Some other rules, affecting the agriculture industry, could also fit in this category. They include the U.S. Department of Agriculture’s final rule regarding production requirements for organic livestock and poultry, establishing minimum indoor and outdoor space requirements for chickens. During his campaign for the White House, Trump said he would pull the United States out of the Paris Climate Agreement within 100 days of taking office. The accord, signed by nearly 200 countries last year, is intended to curb global warming by slashing emissions of carbon dioxide and other greenhouse gases. Since his November election, Trump has softened his stance slightly, telling The New York Times he would keep an open mind about the deal. Nonetheless, the former New York businessman has been advised by his team about swift options he could take to end U.S. participation in the accord, including issuing a presidential order simply deleting the U.S. signature from the accord. 