WASHINGTON, D.C. — Voluntary U.S Environmental Protection Agency programs aimed at cutting greenhouse gases have "limited potential," according to its oversight arm.

Problematic reporting and collection systems mean the programs' accomplishments could be based on unreliable data. The EPA Office of Inspector General (OIR) found the 11 programs it analyzed could, at best, reduce less than 20 percent of the projected 2010 greenhouse gas emissions (non-CO2) for their industry sectors.

"From this, we determined that if EPA wishes to reduce GHG emissions beyond this point, it needs to consider additional policy options," OIG said.

The Bush Administration has historically touted addressing climate change through voluntary action, rather than mandatory caps on greenhouse gas emissions. But it has set a goal of reducing carbon intensity -- not total emissions -- 18 percent by 2012, and agreed with other G8 leaders to reduce emissions 50 percent by 2050.

The OIG report found reporting requirements and the perceived costs of emissions reductions to be the greatest barriers to industry participation. The majority of programs analyzed -- 8 out of 11 -- showed weaknesses in data collection and reporting systems because of limited, unverified and anonymous reporting.

"EPA has been a leader in developing protocols to produce estimates for greenhouse gas sources and sinks categories in the United States," OIG said. "However, data uncertainty has continued to be a concern the voluntary programs have struggled to address."

Current guidelines fail to address data reporting issues: self-certified data with little, if any, required verification; firms may use wide discretion in calculating emissions reductions; and no required supporting documentation.

The data collection processes lack transparency. In some cases, the agency gets data from third parties because of proprietary and data security concerns, hindering the programs from verifying data from individual participants.

Many programs use memoranda of understanding as the written agreement between program and participant but none include verification provisions or penalties for failure to report. The programs in many cases offer little assurance that companies are demonstrating active participation.

The programs examined include: WasteWise, AgSTAR, Natural Gas STAR, reduction programs for the magnesium and electrical power industries, PFC Reduction/Climate Partnership for the Semiconductor Industry, Coalbed Methane Outreach, Landfill Methane Outreach, HFC-23, Coal Combustion Partnership Program, and the Aluminum Industrial Partnership. The report doesn't include emissions from the two largest sources: transportation and energy.

According to OIG, EPA agreed with the majority of its recommendations but expressed concern over safeguarding certain data and creating cost analyses for programs that cover several industry sectors.