Charts show the number of abandoned oil and gas wells in the U.S. since 2000 and their estimated methane emissions.

Calgren's renewable fuels facility that cleans dairy methane into natural gas is shown in Pixley, California, U.S., October 2, 2019. Picture taken October 2, 2019. REUTERS/Mike Blake

Calgren's renewable fuels facility that cleans dairy methane into natural gas is shown in Pixley, California, U.S., October 2, 2019. Picture taken October 2, 2019. REUTERS/Mike Blake

Calgren Environment, Health and Safety Coordinator Paul Lopez looks over the renewable fuels facility that cleans dairy methane into natural gas at his company's facility in Pixley, California, U.S., October 2, 2019. Picture taken October 2, 2019. REUTERS/Mike Blake

Calgren Environmental, Health and Safety Coordinator Paul Lopez (L) talks with SoCalGas project manager Ty Korenwinder at the Calgren methane recycling plant in Pixley, California, U.S., October 2, 2019. Picture taken October 2, 2019. REUTERS/Mike Blake

Calgren's renewable fuels facility that cleans dairy methane into natural gas is shown in Pixley, California, U.S., October 2, 2019. Picture taken October 2, 2019. REUTERS/Mike Blake

Gas is extracted from a coalbed methane well in Jincheng, Shanxi province, China November 14, 2018. Picture taken November 14, 2018. REUTERS/David Stanway

Gas is extracted from a coalbed methane well in Jincheng, Shanxi province, China November 14, 2018. Picture taken November 14, 2018. To match Insight CHINA-POLLUTION/ECONOMY. REUTERS/David Stanway

Methane gas burns from the lava flow that crossed Kahukai St. in the Leilani Estates near Pahoa, Hawaii, U.S., May 25, 2018. REUTERS/Marco Garcia

People attend a meeting, chaired by Ukraine's Prime Minister Volodymyr Groysman (not pictured), after a methane gas explosion at the Stepova coal mine in Lviv region, Ukraine, March 2, 2017. REUTERS/Vladyslav Musiienko/Pool

Medics gather in a building at a compound of the Stepova coal mine after a methane gas explosion in Lviv region, Ukraine, March 2, 2017. REUTERS/Vladyslav Musiienko/Pool TPX IMAGES OF THE DAY

Ukraine's Prime Minister Volodymyr Groysman (L) meets with employees as he visits the Stepova coal mine after a methane gas explosion in Lviv region, Ukraine, March 2, 2017. REUTERS/Vladyslav Musiienko/Pool

Madelyn Jones (L) holds a sign while rallying for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

People wear gas masks as they rally for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

Joni Spiers wears a gas mask while rallying for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

Joni Spiers wears a gas mask while rallying for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni TPX IMAGES OF THE DAY

People hold signs as they rally for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

People hold signs as they rally for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

People hold signs as they rally for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

People hold signs as they rally for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

People hold signs as they rally for the permanent shut down of the Aliso Canyon natural gas storage facility near the Porter Ranch neighborhood in Los Angeles, California February 19, 2016. The underground natural gas pipeline rupture that caused the largest-ever methane leak in California has been permanently capped, paving the way for thousands of displaced Los Angeles residents to return home, state regulators said on Thursday. REUTERS/Mario Anzuoni

Lydia Cua, 68, stands outside the Porter Ranch home where she has lived since 1991, near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. Cua said the gas leak has affected her whole family, and had caused her five-year-old grandson to vomit at night. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Music producer and sound engineer Matt Pakucko works in his Porter Ranch home near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. Pakucko moved into a hotel with his girlfriend after experiencing headaches, a hurt throat, watering eyes, and a persistent cough after the gas began to leak. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

A woman walks past a Porter Ranch sign at the gas company entrance gate near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Music producer and sound engineer Matt Pakucko works in his Porter Ranch home near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. Pakucko moved into a hotel with his girlfriend after experiencing headaches, a hurt throat, watering eyes, and a persistent cough after the gas began to leak. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Porter Ranch homes are seen near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Malind Kumbhojkar, 55, (L) stands with his daughter Simrun Kumbhojkar, 19, outside their Porter Ranch home near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. The family has lived in the home since 1997, but were forced to move into a nearby hotel. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

A mail woman delivers mail to Porter Ranch homes near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Homes are seen in Porter Ranch near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Homes are seen in Porter Ranch near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Homes are seen in Porter Ranch near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

A man cycles wearing a face mask near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Malind Kumbhojkar, 55, sits with his daughter Simrun Kumbhojkar, 19, in the garden of their Porter Ranch home near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. The family has lived in the home since 1997, but were forced to move into a nearby hotel. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Homes are seen in Porter Ranch near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson TPX IMAGES OF THE DAY

A gas company sign marks a fence near the site of the Aliso Canyon storage field where gas has been leaking in Porter Ranch, California, United States, January 21, 2016. Long before the leak, utilities and national industry groups were raising alarms about the danger of aging underground storage infrastructure. Under state regulations, the leaking well’s owner, Southern California Gas, faces a maximum penalty of $25,000 for the leak near Los Angeles, which is unprecedented in scale. The well has spewed methane - a potent greenhouse gas - since October and displaced thousands of people in nearby Porter Ranch. To match Exclusive LOSANGELES-GAS LEAK/REGULATION REUTERS/Lucy Nicholson

Mohammad Zayed carries a bucket of waste to be used in a HomeBioGas portable reactor that turns food leftovers and manure into methane outside his home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Mohammad Zayed fills a bucket with waste to be used in a HomeBioGas portable reactor that turns food leftovers and manure into methane outside his home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Nayef Zayed lights a gas burner running on methane produced in a HomeBioGas portable reactor in his home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Nayef Zayed and his son Mohammad prepare to pour waste into a HomeBioGas portable reactor that turns food leftovers and manure into methane outside their home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Nayef Zayed empties a bucket of waste into a HomeBioGas portable reactor that turns food leftovers and manure into methane outside his home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Mohammad Zayed carries a bucket of waste to be used in a HomeBioGas portable reactor that turns food leftovers and manure into methane outside his home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Nayef Zayed empties a bucket of waste into a HomeBioGas portable reactor that turns food leftovers and manure into methane outside his home in the Palestinian Bedouin village of Ojah, near the West Bank city of Jericho August 17, 2015. Palestinian villagers living in desolate, off-grid areas in the West Bank have begun using Israeli-made biogas generators that supply free, clean energy by gobbling up organic waste. Picture taken August 17, 2015. REUTERS/Ammar Awad

Masawara's Chief Executive Shingai Mutasa gestures during an interview with Reuters in his office in Harare March 5, 2015. Investment firm Masawara Plc is talking to Chinese and Indian companies who have expressed interest to extract coal-bed methane gas at its bloc in north west Zimbabwe, Mutasa said. REUTERS/Philimon Bulawayo (ZIMBABWE - Tags: BUSINESS HEADSHOT)

Messages on methane gas and carbon dioxide emissions are projected onto the United Nations building ahead of the climate change talks that will take place on the sidelines of the U.N. General Assembly, in New York September 20, 2014. REUTERS/Carlo Allegri (UNITED STATES - Tags: POLITICS ENVIRONMENT)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

Frederic Briens, Chief Executive of European Gas Limited poses outside British company's offices in Freyming-Merlebach, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited shows a coal sample at British company's offices in Freyming-Merlebach, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

A coal sample is seen on a map of coalbed methane resources in the Lorraine region at British company European Gas Limited in Freyming-Merlebach, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

An employee of European Gas Limited works on British company's coalbed methane exploration site outside Folschviller, eastern France, February 4, 2013. After slamming the door to potentially huge shale gas reserves over environmental concerns, France has now discovered there could be at least five years worth of another cheap-to-produce gas in the former coal mining region of Lorraine. But, divisions in the French government, as with shale gas, are hampering efforts to develop so-called coalbed methane, a gas extracted from layers of coal too deep underground to be mined. Picture taken February 4, 2013. REUTERS/Christian Hartmann (FRANCE - Tags: ENERGY ENVIRONMENT BUSINESS INDUSTRIAL)

A general view of the Vorkutinskaya mine in Russia's northern Komi region is seen in this August 29, 2011 file photo. A methane gas explosion killed at least 10 miners at the coal pit in northern Russia on February 11, 2013 and rescue workers were trying to save seven more feared trapped underground, government officials said. REUTERS/Eduard Korniyenko/Files (RUSSIA - Tags: DISASTER ENERGY)

A general view of the Vorkutinskaya mine in Russia's northern Komi region is seen in this August 29, 2011 file photo. A methane gas explosion killed at least 10 miners at the coal pit in northern Russia on February 11, 2013 and rescue workers were trying to save seven more feared trapped underground, government officials said. REUTERS/Eduard Korniyenko/Files (RUSSIA - Tags: DISASTER ENERGY)

A man mourns over the body of his brother, who was killed in an explosion sparked by methane gas inside a coal mine in Dasht, on the outskirts of Quetta October 13, 2011. Five miners have been killed and three injured after methane gas sparked an explosion inside a coalmine in Pakistan's southwestern province of Baluchistan on Thursday, local media reported. REUTERS/Naseer Ahmed (PAKISTAN - Tags: DISASTER)

Relatives and rescue workers carry the body of a victim who was killed in an explosion sparked by methane gas inside a coal mine in Dasht, on the outskirts of Quetta October 13, 2011. Five miners have been killed and three injured after methane gas sparked an explosion inside a coal mine in Pakistan's southwestern province of Baluchistan on Thursday, local media reported. REUTERS/Naseer Ahmed (PAKISTAN - Tags: DISASTER)