WASHINGTON (AP) - Energy independence has been a goal of every president since Richard Nixon, but it remains elusive.
Still, an ongoing drilling boom has lowered dependence on imports of fossil fuels such as oil and natural gas. In 2015, the U.S. relied on net imports for about 24 percent of petroleum use, the lowest level since 1970.
Domestic production of all types of energy except coal has boomed in recent years, thanks to improved drilling techniques and discoveries of vast oil supplies in North Dakota and Montana and natural gas in states such as Pennsylvania, Ohio and West Virginia. Hydraulic fracturing - a drilling technique better known as fracking - has also increased production in traditional energy states such as Texas, Oklahoma and Louisiana.
After President Barack Obama's two terms, business and environmental groups see a game-changing election on energy. Donald Trump has vowed to ramp up oil and gas production even further, while rolling back Obama policies aimed at slowing climate change and boosting renewable energy.
Hillary Clinton says she will expand Obama's climate policies and push even harder for renewable energy such as wind and solar power that have gained under Obama. Meanwhile, Clinton's comment that she is going to "put a lot of coal miners and coal companies out of business" has become a rallying cry for the GOP.
Natural gas, cleaner than coal, has been embraced by politicians from both parties, including Clinton and Trump. Still, critics worry that fracking and other techniques such as horizontal drilling could be harming our air, water and health and even causing earthquakes.
Wind and solar power have grown in recent years, thanks in part to support from Obama, but renewable energy sources accounted for just 10 percent of total U.S. energy consumption in 2015. Renewable energy is generally more expensive to produce and use than fossil fuels. Clouds impair solar energy, and calm skies slow wind farms.
Here's a summary of their proposals:
OIL AND GAS
CLINTON: She generally supports oil and gas drilling on federal lands, but would bar drilling in the Arctic and Atlantic oceans. While Clinton would cut subsidies currently given to oil companies, she has said natural gas serves as an important "bridge" to more renewable fuels. She says fracking should not take place where states and local communities oppose it and pledges to reduce methane emissions from all oil and gas production and protect local water supplies. She also would require energy companies to disclose the chemicals used in fracking.
TRUMP: He complains that "energy is under siege by the Obama administration" and vows to "unleash" an American energy revolution, allowing unfettered production of oil, coal and natural gas. He would sharply increase oil and gas drilling on federal lands and open up offshore drilling in the Atlantic Ocean and other areas where it is blocked.
Trump says restrictions supported by Clinton would hurt energy-producing states such as Colorado, Pennsylvania, North Carolina and Virginia - battleground states in the election.
CLINTON: Pledges that under her leadership, the U.S. will be able to generate enough renewable energy to power every home in America within 10 years, with 500 million solar panels installed by the end of her first term. She also vows to reduce U.S. oil consumption by one-third through cleaner fuels such as biodiesel and natural gas and more fuel-efficient cars, boilers, ships and trucks.
Clinton vows to use tax incentives and other steps to bolster wind and solar power, as well hydroelectricity, geothermal power and other forms of renewable electricity.
TRUMP: Argues that tax credits and other subsidies for wind and solar power "distort" the market, but says the U.S. should "encourage all facets of the energy industry," including wind and solar power, as a way to achieve energy independence. He has characterized solar energy as an "unproven technology" with a low return on investment and says wind energy has killed birds and is a "very, very poor source of energy."
CLINTON: After running as a champion of coal in 2008, Clinton has faced a backlash from coal communities after she declared earlier this year that she was going to "put a lot of coal miners and coal companies out of business." Clinton has said she misspoke as she tried to reassure voters that her policies would benefit out-of-work miners and other poor people in Appalachia affected by the coal industry's downturn.
Clinton says she will protect health and pension benefits for coal miners and fight efforts by coal companies to use bankruptcy proceedings to deny benefits to thousands of retired miners and their families. She supports sweeping reforms to the federal black lung benefits program and will adjust black lung benefits to reflect cost-of-living increases.
TRUMP: Vows to revive the struggling U.S coal industry and says the U.S. has enough coal reserves to "last for 1,000 years." He vows to end "all job-destroying Obama executive actions as well as reduce and eliminate all barriers to responsible energy production." He says his plan "will end the war on the American worker, putting our coal miners and steel workers back to work."
CLINTON: Calls climate change a real and urgent problem and says the U.S. can take the global lead in addressing it. She vows to meet Obama's goal to reduce greenhouse gas emissions by up to 30 percent by 2025 and says America "can rally the world to cut carbon pollution" while fulfilling "our moral obligation to protect this planet for our children and our grandchildren."
TRUMP: Calls climate change a "hoax" perpetrated by China and others and says he will rescind Obama's Clean Power Plan rules to curb greenhouse gas emissions from the utility sector. The plan, a lynchpin of Obama's climate strategy, has been delayed by the Supreme Court while legal challenges are heard. Trump also would cancel the 2015 Paris climate agreement and stop U.S. money going to U.N. global warming programs.
CLINTON: Offers cautious support for nuclear power, calling it a tool to address climate change.
TRUMP: Says he will ensure the U.S. remains the world's leader in nuclear energy.