Air board targets cuts to climate pollutants like methane, black carbon

By Anne C. Mulkern | 10/01/2015 08:46 AM EDT

California launched its next attack on the climate front yesterday with a proposal on how to cut short-lived climate pollutants like black carbon, methane and refrigerator gases.

California launched its next attack on the climate front yesterday with a proposal on how to cut short-lived climate pollutants like black carbon, methane and refrigerator gases.

In a draft strategy, the Air Resources Board (ARB) said it would seek a number of changes to pare the pollutants, part of its effort to limit the global temperature increase to 2 degrees Celsius. Short-lived climate pollutants (SLCPs) remain in the atmosphere for a shorter period of time than carbon dioxide and other longer-lived greenhouse gases but are estimated to be responsible for about 40 percent of current "net climate forcing," it said.

"The impacts of climate change are already upon us," the draft said. "California continues to suffer through historic temperatures, drought, and wildfires, and the State faces the prospect of an epochal El Niño season in the coming winter. Each year seems to bring a new global temperature record, and new evidence suggests sea levels are rising much faster than predicted."


"While the climate impacts of CO2 reductions take decades or more to materialize, cutting emissions of SLCPs can immediately slow global warming and reduce the impacts of climate change," the draft added.

The draft offers a number of proposals, including regulations on several fronts. The agency is expected to look at options later this year. The goal is by 2030 to cut yearly emissions of several pollutants from 2013 levels. ARB seeks to shrink black carbon pollution to 19 million metric tons of carbon dioxide equivalent (MMTCO2e) from 39 MMTCO2e by 2030; methane to 71 MMTCO2e from 118 MMTCO2e; and fluorinated gases (F-gases) to 24 MMTCO2e from 40 MMTCO2e.

The largest source of black carbon emissions in California, by far, the paper said, is wildfire.

"An average wildfire season contributes two-thirds of current black carbon emissions in California," it said. "Because of climate change and drought, many of California’s forests are already in a perilous condition and require accelerated management and investment to protect them."

Several federal, state and local agencies are working on a comprehensive "Forest Carbon Plan," which is expected to be released next year.

"As part of this and related efforts, black carbon mitigation will be considered along with forest health, carbon sequestration, habitat and watershed production, and other drivers associated with protecting our forests," it said.

Thinning of forests could reduce ‘black carbon footprint’

In addition to that, it said, there should be a look at removing dead growth in forests. Right now, it said, the "current rate of fuel reduction activity is insufficient to improve forest health and avoid catastrophic wildfire and produce resilient forests."

That removed wood and other products should not be burned, which right now is common practice, the draft said.

"Finding a productive use for this forestry residue, such as in bioenergy or liquid fuels production, can help California reduce its forest-derived black carbon footprint while meeting renewable energy and low carbon fuel goals, providing jobs, fostering rural economic development, and enhancing energy security," it added.

ARB also will seek to cut soot produced by fuel combustion in the industrial and power sectors and burning of wood fireplaces in residences.

"Reducing 2030 residential wood combustion black carbon emissions by half … would set California on a path toward meeting the 2030 target proposed in this Draft Strategy," the paper said.

ARB is proposing teaming with local air districts to "determine the most effective approach to avoid new residential wood combustion emissions in California. This could include encouraging the installation of gas fireplaces or non-wood burning centralized heating in new construction."

Targeting methane emissions at dairies, landfills

Methane emissions need to be cut because they are the second-largest source of greenhouse gas emissions globally.

"Agriculture represents the largest methane source in California, accounting for nearly 60 percent of methane emissions," the ARB paper said. "Landfills are the next largest source of methane, accounting for a fifth of statewide methane emissions. Pipeline leaks, oil and gas extraction, wastewater, and other industrial and miscellaneous sources make up the remainder of emissions."

California has the most dairy cows in the country and with those, the highest aggregated dairy methane emissions, it said.

ARB in the paper proposed regulating new dairies by 2018 with rules for manure management. It likely would also cover expansions at existing dairies that occur on or after the effective date of the proposed regulation.

In many cases, installing anaerobic digesters at dairies may not yet be cost-effective, if the only marketable product is energy, the draft said. But offering environmental credits may help "offer attractive rates of return for farmers and investors."

ARB also should look at requiring diversion of organic material from landfills, the paper said. Under one proposed regulation, material would be diverted to organics recycling facilities to make useful products, including compost, fuel or energy.

"These facilities may be developed at existing landfill and other waste management sites, or at new stand-alone sites," the draft said. "Organic wastes could also be diverted to regional waste water treatment plants or dairies for co-digestion with wastewater sludge, biosolids, or manure."

Working with local air boards, ARB already is looking at a rule to cut vapor emissions of methane from oil and gas production, processing and storage. It likely will require: vapor collection on uncontrolled oil and water separators and storage tanks with emissions above a set methane standard; vapor collection on all uncontrolled well stimulation circulation tanks; leak detection and repair on components; and several other changes.

New refrigerants spike GHGs

F-gases are the fastest-growing source of greenhouse gas emissions both globally and in California, the paper said. The majority of those come from "fugitive emissions of refrigerants used in refrigeration and air-conditioning (AC) systems."

More than half of refrigeration and air conditioning equipment uses HCFC-22, a pollutant that’s scheduled for a nationwide phaseout by 2020. But that refrigerant is being replaced with hydrofluorocarbons (HFCs) that have higher global warming potentials (GWPs), increasing the greenhouse gas impact of refrigerants, the paper said.

"A window of opportunity exists in the next five years to accelerate the transition of refrigeration and air-conditioning equipment to lower-GWP refrigerants, before another generation of equipment is locked into using higher-GWP refrigerants over their average lifetimes of 15 to 20 years," the proposal said.

On the international stage, countries will meet in Dubai, United Arab Emirates, in November to discuss an HFC phase-down effort. Depending on what happens there, ARB might pursue a California schedule on an HFC phase-down "that will meet the State GHG emission reduction goals," the draft said.