The relentless march of the states to greater use of renewable energy has hit some bumps on the road.

The biggest bump occurred in Ohio, where the Legislature last month approved a law delaying the state’s commitment to obtain 25 percent of its energy use from renewable energy by 2025. The Ohio measure was the latest battle in a regional assault on renewable standards by Republicans, who contend that green energy mandates are expensive and threaten economic growth.

In the Kansas Legislature, a measure to revise clean-energy standards was narrowly defeated, but proponents vow they will try again. In April, the Indiana Legislature took the dramatic, if largely symbolic, step of eliminating the state’s energy-efficiency standards.

The Ohio measure is “clearly a setback” for renewable energy, said Dick Munson, director of Midwest Clean Energy for the Environmental Defense Fund. But he does not see it as a lasting defeat. Munson observed that many other states are adhering to commitments to increase use of renewables or expanding these goals.

California, the poster child for renewable energy, is on target to meet its goal of generating a third of its energy from renewables by 2020, according to Lauren Navarro, Munson’s counterpart in the Golden State.

The landmark California measure was supported and signed into law by Gov. Arnold Schwarzenegger in 2002. It has been embraced by his successor, Gov. Jerry Brown, and twice expanded since its enactment. In 2010, California voters rejected a ballot initiative that opponents said would cripple the law.

Following California’s lead, some 30 states in the last dozen years have adopted mandates, known as renewable portfolio standards, which set goals for utilities to increase their percentage of green energy use. They have for the most part been widely accepted, but some utility companies such as FirstEnergy in Ohio have balked at the goals or the means of achieving them. Wind and solar power are subsidized in various ways by federal, state and local governments. In Ohio, some Republicans argued that the costs of producing these alternative energies have declined enough that they should stand on their own feet without subsidies.

The argument cuts two ways. The reduced costs of producing renewable energy may weigh against continued subsidies but they also herald a day when renewable energy will routinely be part of the electrical generation mix. A recent study of 24 states with renewable portfolio standards by the National Renewable Energy Laboratory in Golden, Colo., and the Lawrence Berkeley National Laboratory in Berkeley found they increased utility bills by only 1 percent.

Nationally, renewable energy accounts for about 10 percent of U.S. energy consumption and 13 percent of electricity generation. More than half of this electric power comes from water (hydropower) and roughly a third from wind power. The rest comes from biomass wood and waste, geothermal and solar, which accounts for only 2 percent of renewable energy generation.

In signing the Ohio bill, Gov. John Kasich took credit for brokering what he called a balanced compromise between clean-energy advocates and “those who would like to kill renewable energy altogether.” The bill delayed by two years the Ohio target of obtaining 25 percent of its energy from alternative sources by 2025. During this two-year freeze, as Kasich calls it, a commission will study the issue.

Some environmentalists don’t believe the Ohio delay is truly balanced. Noting that Kasich had also approved a $400 million state budget restricting wind farm siting, the green energy website, CleanTechnica, headlined its report on the Ohio situation: “Ohio to Wind Power: Drop Dead.” (This echoed, “FORD TO CITY: DROP DEAD,” a 1975 headline in the New York Daily News after President Gerald Ford denied federal bankruptcy assistance to New York City.)

Balanced or not, the Ohio bill and Indiana’s scrapping of its efficiency standards, have raised doubts that are not helpful to the cause of renewable energy.

“Energy markets are highly policy-driven,” Todd Foley of the American Council on Renewable Energy told The New York Times. “When states and even the federal government continually revisit these policies, it sends a signal of uncertainty. It chills market and investment momentum.”

But this momentum, even if slowed, may be inexorable. The U.S. Energy Information Administration (EIA) reported in July that renewable consumption for electricity and heat generation is on track to grow by nearly 3 percent in 2014 and by 4 percent in 2015. Munson believes this trend is irreversible.

Two recent developments may have given alternative energy a boost. The first was a June announcement by President Barack Obama of a climate-change initiative intended to reduce carbon pollution from power plants by 30 percent by 2030. Later in the month, the U.S. Supreme Court upheld the Obama administration’s efforts to regulate greenhouse gas emissions from power plants. The 7-2 ruling, in which Chief Justice John Roberts and Justice Antonin Scalia joined the court’s moderates and liberals, was the latest in a string of decisions endorsing the Environmental Protection Agency’s authority to issue Clear Air Act regulations to curb climate change.

The administration’s efforts to curb carbon emissions, especially from coal, come at a time of extensive natural gas production that has brought the United States to the brink of energy independence. Thirty-nine of total U.S. electricity generation in 2013 came from coal, but natural gas accounted for 27 percent of the generation and is rapidly gaining.

A year ago Citigroup predicted that the United States — or at least North America — could be energy independent by 2020. By then, according to the consultancy firm, McKinsey & Co., U.S. energy consumption could be down 23 percent with increased use of energy-efficiency measures.

Energy efficiency is important because there’s no free lunch in energy generation. Much of the increased natural gas production comes from the hydraulic fracturing or fracking of shale, a process that releases toxic emissions and is under political attack.

Hydropower will experience a slight downturn in 2014, according to the EIA, even as electricity generation from other renewable energy sources increases, largely because of the Western drought. Wind power, which is expanding globally, is criticized for the destruction of bird flocks.

Despite such obstacles and the pullback in Ohio and Indiana, renewable energy projects continue to entice. Early this year, Los Angeles Mayor Eric Garcetti promised that his city, the second most populous in the nation, would derive 20 percent of its electricity from rooftop solar power by 2020.

This month, in North Carolina, two universities, a hospital and the utility Duke Energy declared they will soon begin construction of a 52-megawatt solar project, the largest east of the Mississippi River. Encouraging others to follow suit, the federal government recently announced it would make $4 billion available in loan guarantees for innovative renewable energy and energy-efficiency projects that avoid or reduce greenhouse gases.

California continues to show the way on renewable energy and its accomplice, energy efficiency, which Navarro calls the “lowest hanging fruit” in the effort to reduce carbon pollution. Under a program known as “demand response,” utility users lower thermostats during periods of peak electricity use in return for a refund on their electricity bills. Although still in its infancy, this program is seen by the California Public Utility Commission as the wave of the future.

What happened in Ohio is a reminder that the path to alternative energy is not straight. The ultimate direction is nonetheless clear.

As the American Council on Renewable Energy declared in its 2014 forecast: “The potential of America’s clean energy … provides the country with an unparalleled opportunity to reinvigorate our economy while protecting our environment.”

Lou Cannon, a Summerland resident, is a longtime national political writer and acclaimed presidential biographer. His most recent book — co-authored with his son, Carl — is Reagan’s Disciple: George W. Bush’s Troubled Quest for a Presidential Legacy. Cannon also is an editorial adviser to State Net Capitol Journal, which published this column originally. Click here to read previous columns. The opinions expressed are his own.

Lou Cannon, a Summerland resident, is a longtime national political writer and acclaimed presidential biographer. His most recent book — co-authored with his son, Carl — is Reagan’s Disciple: George W. Bush’s Troubled Quest for a Presidential Legacy. Cannon also is an editorial adviser to State Net Capitol Journal, which published this column originally. Click here to read previous columns. The opinions expressed are his own.