Shareholders of one of the country's biggest hotel chains have struck down a resolution that would force the company to consider replacing energy-guzzling shower heads with more efficient ones—yet its backers are claiming victory.

Although only nine percent of Choice Hotels shareholders voted in favor of the resolution, the proposal is one of a handful of global warming resolutions that companies tried to dismiss in this year's proxy season—but that the U.S. Securities and Exchange Commission said must be put to a vote. The trend reflects continued concerns by the SEC about the business risks of climate change.

"They're enforcing their rules in a way that allows a lot more climate-related resolutions to go through to a vote," said Rob Berridge, program manager at Ceres, a coalition of sustainability focused investors with $11 trillion in assets.

Congressional lawmakers from both parties are taking a step to catalyze the nation's clean energy economy: After 32 years of restricting a crucial investment tool to expanding fossil fuels, they're pushing to open it to renewables.

Legislation is moving through both houses to tweak the tax code to let clean energy developers form a master limited partnership, or MLP, a type of publicly traded company structure not subject to corporate taxes.

For three decades, coal, oil and gas companies have used MLPs to raise hundreds of billions of dollars for pipelines, refineries and other projects. The financing vehicle is credited with helping sustain the nation's current drilling boom.

It has been more than a month now, and Amber Bartlett has had enough of hotels and apartments and trailer homes. Of crowded rooms whose thin walls amplify the bickering of her four children. Of piles of toys and clothes overflowing from drawers and suitcases. Of not knowing, day to day, where her life is headed.

She wants to be back in her five-bedroom, three-bathroom home at 16 Starlite Road North in Mayflower, Ark.

Ryan Senia, the Bartletts' next-door neighbor, is plenty ready to go home, too. For the past month the 29-year-old electrical engineer has been sleeping on a friend's couch instead of in his bed at 20 Starlite Road North. His power tools and equipment are gathering dust in his garage. His grill sits in his backyard, unused.

The Bartletts and Senia are among 21 families who were evacuated from their homes on March 29, after an ExxonMobil pipeline spilled at least 210,000 gallons of heavy Canadian crude oil into their neighborhood.  

Federal agencies have so far not decided whether to undertake an assessment of the ecological harm caused by ExxonMobil's pipeline break, which spewed a tarry oil slick into yards, streets and creeks in a central Arkansas town.

For now, they're leaving it to state agencies to decide whether and how to quantify and counteract the environmental damage.

The rupture in the Pegasus pipeline on March 29 dumped up to an estimated 294,000 gallons of Canadian heavy crude in Mayflower, Ark.—including in a cove that flows into Lake Conway, a major fishing lake. If that estimate turns out to be correct, the Arkansas spill would be one-third the size of a 2010 Michigan pipeline spill, the worst accident of its kind in U.S. history.

When ExxonMobil's Pegasus pipeline ruptured last month in Mayflower, Ark., it was carrying diluted bitumen, a controversial form of oil from Canada's tar sands region. That was confirmed in a letter an Exxon lawyer wrote to the U.S. Environmental Protection Agency last week.

But the letter contradicts public assertions by company officials that the spilled oil was simply "heavy oil," not tar sands bitumen. It also raises, once again, the question that surfaces after every spill involving oil from Canada: Is it or isn't it diluted bitumen?

Bitumen is a semi-solid form of crude oil found in Canada's vast oil sands region, where it is found with sand, clay and water in formations dating back hundreds of millions of years. Because bitumen is so thick and tarry, producers dilute it with natural gas liquids or light oil so it can flow through pipelines. That creates a type of oil called diluted bitumen, or dilbit.

The letter Exxon sent to the EPA on April 10 was a response to the EPA's request for more information about Wabasca Heavy—the oil that poured out of a 22-foot-long gash on its Pegasus line on March 29. "Can the oil accurately be described as tar sands oil, or a type of diluted bitumen (dilbit)?" the EPA had asked in an April 5 letter to Exxon.

When ExxonMobil's Pegasus pipeline ruptured on March 29, the company announced that no oil had leaked into Lake Conway, a major recreational reservoir just nine-tenths of a mile from the spill site in central Arkansas.

Some oil had spilled into a "cove adjacent to" the lake, the company said, but "Lake Conway remains oil free," according to news releases Exxon issued as recently as April 5.

That position has sparked a debate over where Lake Conway—one of Arkansas' premier fishing spots—begins and ends.

Arkansas Attorney General Dustin McDaniel told reporters, "I don't understand where this distinction is coming from. ...The cove is part of Lake Conway."

On Saturday, Exxon acknowledged that subtlety for the first time. "There is no oil in the main body of Lake Conway," according to a news release on Apr. 6—and an Exxon spokesperson on Tuesday.

An upstart company in Ohio is aiming to disrupt the oil pipeline business with new technology that resists corrosion far more effectively than conventional pipe.

MesoCoat, Inc. says its technology will become especially crucial as global oil production shifts to more sulfurous and heavier fuels like tar sands crude. It claims it can make pipelines safer from potential leaks and save oil companies hundreds of millions of dollars by reducing the frequency of replacing corroded pipes.

At just six years old, MesoCoat is already attracting interest from major oil companies and research centers in Alberta, home of Canada's vast oil sands resources. It has won five R&D 100 awards for innovation, plus an award from the National Institute of Standards and Technology, a U.S. agency. In the fall, it took the top spot in The Wall Street Journal's Technology Innovations Awards for manufacturing.

The global attention is helping MesoCoat leap from startup to commercial company. But for Canada's tar sands industry, the attention appears to be coming at a less-than-opportune time, as it lobbies hard for approval of the Alberta-to-Texas Keystone XL pipeline.

One of the main objections to the Keystone is the possibility that the tar sands oil it would carry is more corrosive to pipelines than ordinary crudes, with implications for oil spills. That concern deepened last week after an ExxonMobil pipeline carrying bitumen ruptured and leaked at least 200,000 gallons of the tarry crude in an Arkansas neighborhood.

Go to Our News Center for Full & Expert Coverage of Exxon's Arkansas Oil Spill

Despite little success so far and growing support nationally for clean energy, a multi-pronged campaign to undercut renewable power mandates in the states is showing no signs of letting up.

Over the past few years, a rising tide of legislation has sought to repeal or weaken renewable portfolio standards (RPS), which require a certain share of a state's electricity supply to come from sources like solar and wind. Lesser known are the few lawsuits filed to challenge the constitutionality of these laws.

Many of these attempts have fizzled, but some are being revived this year. In total, 42 separate efforts are wending their way through legislatures and courts in more than two dozen states, according to the North Carolina Solar Center, a clearinghouse for state renewable energy policies.

"The danger of some of these [RPS laws] being repealed is a little bit greater this year than it was last year," said Justin Barnes, a senior policy analyst at the center.

Prominent Canadian economist Robyn Allan made waves in Canada last year with papers claiming that rapid oil sands growth would do more economic harm than good for her country.

Allan's controversial analyses focused on the Northern Gateway pipeline, a proposal to carry raw tar sands bitumen through British Columbia for shipment to Asia. One of her main points was that shipping raw crude for upgrading and refining in other countries also means exporting those industries—and jobs—abroad. 

She also warned that increased oil sands exports would drive up the value of Canada's currency. Already, an inflated "petro-dollar" is making it tough for Canadian goods to compete in export markets and is "hollowing out" manufacturing sectors, she said.

Now, Allan is making the same arguments about an even bigger and more contentious export pipeline: the Keystone pipeline. If approved by the Obama administration, the Keystone pipeline would send 830,000 barrels of bitumen a day from Alberta to the Texas refining hub.

Allan, a former CEO of the Insurance Corporation of British Columbia, one of Canada's biggest insurance firms, says that through presentations, meetings and op-eds she's trying to "balance out" the economic debate on the Keystone pipeline, which she claims has been reduced to a simple choice between jobs and the environment.

"There are economic costs that haven't been considered," she says.

In an extensive interview, Allan—who supports measured oil sands development—explains her position on the Keystone pipeline and discusses potential economic risks to Canadians if it's approved.

Two advocacy groups have come up with a new tactic to show how climate change—and laws to deal with it—could make investments in fossil fuel companies riskier and rock financial markets.

In a pair of first-of-their-kind shareholder resolutions, the groups have asked two of the nation's largest coal producers to report to investors how much of their coal assets would be left "stranded" in the ground if the United States were to pass sweeping greenhouse gas regulations.

As You Sow, a shareholder advocacy group for environmental issues, filed a resolution with CONSOL Energy late last year. The Unitarian Universalist Association, a religious organization that promotes social justice, filed a similar resolution with Alpha Natural Resources.

The groups' point is that coal and other energy companies would be dangerously overvalued in a carbon-regulated world, thus creating a "carbon bubble" that could one day pop.

"This carbon bubble is so big, it's going to make the housing bubble look like chump change," Andrew Behar, CEO of As You Sow, said in an interview. "It's another order of magnitude."

The carbon bubble concept is relatively new, born out of a recent scientific paper that has united climate change activists and some in the financial community in a common pursuit: to rethink the value of investments in coal, oil and gas.