California’s continuing push to decarbonize its energy systems increasingly point to the transportation sector and natural gas as obvious “elephants in the room,” according to the state’s 2016 Integrated Energy Policy Report (IEPR) update released earlier this month by the California Energy Commission (CEC).

While the update continues to celebrate the steady transformation of the electricity generation system that has more than tripled the amounts of renewable resources since 2000, it also acknowledged that 37% of the state’s greenhouse gas (GHG) emissions come from the transportation sector, which is still heavily reliant on petroleum-based products.

The IEPR also recognized that with the increase in renewables comes the growing need for “more resources that can quickly and cost-effectively ramp up or down to balance supply and demand and to compensate for the intermittency of renewable generation.” That is code for “natural gas.”

However, the report also noted the state’s “legacy of aging energy infrastructure,” illustrated by the four-month storage well methane leak at the Aliso Canyon underground storage facility. Given the state’s precedent-setting efforts to reduce GHG emissions, the IEPR made clear that “more work is needed to decarbonize” California overall, and it suggested that progress in changing the electricity system and still maintaining reliability indicates the bigger effort can eventually be successful.

“California must dramatically reduce emissions even as its population is expected to grow from about 38 million today to more than 44 million by 2030,” the authors noted, adding that the rapid increase in the state’s renewable resources has “brought new challenges for grid operators trying to maintain reliability while managing swings in wind and solar generation.”

While touting the need to move further away from fossil fuels, “natural gas-fired power plants offer the most flexibility for quickly, reliably and cost-effectively ramping up or down to balance supply/demand,” the IEPR stated. California relies on ramping up using natural gas in peaking plants, “even as it is moving away from using it…” Last summer, “gas use was down 20% compared to the previous year in the state due to better hydroelectric conditions and more renewables.”

Nevertheless, only so much added energy storage and demand response can be added, so the IEPR said that the state “will likely depend on some natural gas-fired generation to meet its needs for flexibility.”

In addition, for the first time, the IEPR highlighted the state’s 12 gas storage facilities and the overall leaks from the statewide gas system in the context of addressing climate change mitigation issues. The state is “grappling with the legacy of an aging energy infrastructure,” the IEPR noted, citing Aliso Canyon and the unexpected closure of the San Onofre Nuclear Generating Station as recent examples.

Underscoring the emphasis that gas storage is now getting from state officials, the IEPR highlighted a suite of new state laws passed last year to the address a previously unnoticed part of the state’s energy infrastructure including:

“Apart from the major leak at Aliso Canyon, there are concerns about ongoing leaks that occur throughout the natural gas system, including extraction, transmission, distribution and end use,” the IEPR stated. A new law (AB 1496) requires the California Air Resources Board to monitor methane emissions and conduct life-cycle analysis of natural gas.

The statewide report also acknowledged that Aliso Canyon remains “critical to the natural gas transmission and distribution system in Southern California.” And it notes that “the current constraints are unprecedented, creating uncertainty about the reliability of energy system operations in the region.”