In 2005, then-Governor Arnold Schwarzenegger threw down a hefty gauntlet in the form of Executive Order S-03-05. The target: reduce greenhouse gases (GHGs) more than 80 percent from 1990 levels by 2050.
The California Council for Science and Technology has now completed a two-year study of just what technologies will be needed to reach the target. The short answer: everything andthen some. In a surprise finding, the availability of bioenergy wasfound to be the single most important limiting factor in reaching the 2050 goal.
Since that landmark Executive Order, the California Legislature has enacted legislation to encourage low-carbon technologies. Assembly Bill 32, The Global Warming Solutions Act of 2006, put a 2020 GHG target officially on the books. It also paved the way for the Renewable Portfolio Standard that requires 33 percent renewable electricity by 2020, and for adoption of California’s landmark 2009 Low Carbon Fuel Standard.
California’s 2050 GHG goal may be among the most ambitious anywhere, but the report’s findings and the important role of bioenergy provides a useful case study in any effort to substantially reduce GHG emissions.
The study, California’s Energy Future: The View to 2050, was convened to take an integrated look at California’s entire energy system and explore technically feasible solutions to meet the 2050 target. The working group discovered very early that our standard of living comes at a very high energy cost and there is no silver bullet to reduce the greenhouse gas emissions associated with that energy. In the end, the working group settled on a simple integrated approach with four main steps:
1. Increase Efficiency
Reduce demand as much as possible through increasing energy efficiency in buildings and transportation.
Shift demand from fuels to electricity where it is most efficient (electrification of the cars and light-duty trucks, home heating and cooking, and all but very energy-intense industrial processes).
3. De-carbonize electricity
Reduce the fossil carbon emissions of electricity as much as possible through use of renewable technology (wind, solar, hydro, geothermal, etc.) alone or with nuclear power. Alternatively, deploy some renewables and implement carbon capture and sequestration for any remaining fossil emissions.
4. De-carbonize fuel
Reduce the fossil emissions of liquid and gaseous fuels needed for heavy-duty transport, air transportation, and heavy industry as much as possible by replacing petroleum and natural gas with advanced drop-in biofuels, lignocellulosic ethanol,and biogas.
The multi-disciplinary analysis team found that any one of these four efforts on its own was insufficient to reduce GHGs more than 50 percent. In fact, implementing all four strategies still fell just short of the goal. This was largely because emissions from the fuel sector, limited by biomass availability, were still too high.
Efficiency and electrification go hand-in-hand to reduce energy demand overall but with a sizable shift in demand from fuel to electricity. The final working scenario projects reduced overall energyuse in buildings and industrial processes by 72 percent and reduced energy use in transportation by 56 percent.
The highly optimistic approach included, for example, replacement or deep efficiency retro fitting of all commercial and residential buildings, eliminating consumer natural gas (in-home natural gas furnaces and cooking stoves), and replacing 70 percent of cars and light trucks with plug-in electric vehicles.
Three separate highly optimistic scenarios were examined to decarbonize electricity. One scenario maxed out renewable technologies as a portfolio of 40 percent solar, 40 percent wind, 10 percent geothermal, 5 percent hydro, and 5 percent biomass.
The other two scenarios limited renewables to 33 percent of total supply, in compliance with California’s Renewable Portfolio Standard. One scenario used nuclear power to make up the remaining two-thirds of demand, the other called for continued fossil fuel use with carbon capture and sequestration.
Biomass was important for de-carbonizing both electricity and fuels. The need for biofuels was obvious—they are currently the only option for de-carbonizing liquid fuels for heavy-duty transport that can reach commercial scale by 2050. The need to increase the biomass portion of the renewable electricity portfolio was underestimated.
Technologies such as wind and solar are intermittent. To robustly meet demand, they must be augmented with a source of steady baseload power as well as fast- ramping capability to deal with peaking demand. While nuclear and biomass can both meet the baseload requirement, only natural gas can provide the fast-ramping load balancing capability. But, emissions from load balancing with natural gas (fossil methane) alone exceed the GHG target for the whole energy system. Biogas (methane from biomass) is currently the only renewable substitute for this need.
After applying efficiency and electrification, demand for liquid and gaseous fuels was about 23-29 billion gallons of gasoline equivalents for transportation and heavy industry. California could produce 7.5 billion gallons of gasoline equivalents per year mainly from agricultural, forest, and municipal waste biomass. The committee limited biofuels imports to a equivalent volume, leaving a gap of 8 to 14 billion gallons.
This gap, caused by the limitations on biomass production and import, proved to be a key factor in failing to meet the GHG goal. Of all the alternative scenarios tested, only increasing biomass met the goal.
California legislators will be faced with difficult choices about incentivizing in-state biomass production versus importing fuels from the Midwest or beyond.
Even with an import tariff in place, it is substantially cheaper for California to import a gallon of ethanol from Brazil than it is from Iowa with the current infrastructure.
Increasing in-state biomass for energy will require increasing the sustainable recovery of residue biomass (from crop, forest, and municipal waste) and implementing novel sustainable energy crops designed specifically for California.
Shifts in land use and changes in the current agricultural, forest maintenance, and timber practices may also be needed. The use of organic municipal waste (40 percent of California residue biomass) for energy remains controversial and public resistance to siting and permitting biomass-to-energy plants remains high. These factorsare significantly slowing implementation of bioenergy projects and will only delay GHG reductions.
The California’s Energy Future study confirms we need the entire arsenal of energy use reduction and alternative energy production to lower greenhouse gases.
The study, applicable to any energy system, also clearly shows that physical solutions alone are not enough. Biologyhas a very important role to play in our energy future. Our success at mitigating greenhouse gases in the next half-century hinges on finding sustainable bioenergyoptions and integrating them in our larger low-carbon energy infrastructure.