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Can California Reduce Its Carbon Footprint by 80 Percent?

Although a number of states are backing away from their earlier greenhouse-gas reduction targets and regional climate initiatives, California is going full steam ahead to meet the goal of reducing its emissions 80 percent by 2050, relative to a 1990 baseline level.

During the past year, California’s Air Resources Board has been preparing for the 2012 start of the state’s cap-and-trade program. The program aims to limit greenhouse gases by requiring emissions permits — initially from large power plants and industrial facilities, and beginning in 2015, from distributors of fossil fuels as well. When the Canadian provinces of British Columbia, Ontario and Quebec formally joined with California in mid-April, they earned the distinction of creating the largest regional carbon market in North America. Just weeks before reaching that benchmark, California’s legislature enacted SB2X, which raised the state’s renewable portfolio standard to 33 percent by 2020, thereby establishing the most ambitious near-term goal in the U.S.

These actions reflect the impact of policies originating in 2005 and 2006 with the Global Warming Solutions Act  (AB 32) and executive order S-3-05, mandates that are also unique in setting enforceable penalties for failure to meet the economy-wide caps by 2050. The goal is an ambitious one, matched in the U.S. by only New York and Massachusetts.1 But despite all the efforts to move California along a clean energy path, it is only in recent months that anyone could say with accuracy whether the aggressive target could be achieved, and if so, precisely how the state could get there.

This advance stems from the work of a blue-ribbon panel of scientists, convened by the California Council on Science and Technology, a nonpartisan, non-profit corporation created by the legislature to provide expert advice. While the final draft of its report on California’s energy future is undergoing peer review, the authors have summarized results for select scientific audiences — in February at the annual meeting of the American Association for the Advancement of Science in Washington, D.C., and in April at the Lawrence Berkeley National Laboratory in California.2

“The short answer to the fundamental question about the target is ‘yes’, we can get there and still meet our energy needs,” said Jane Long of Lawrence Livermore National Laboratory, a co-chair of the panel. But doing so will require a sweeping transformation of energy production and consumption in the state that presents significant challenges, she said

In developing their report, the panel members, who are affiliated with several California universities and research laboratories, agreed to restrict themselves as much as possible to current or largely demonstrated energy technologies. Under this constraint, it is possible to lower the state’s emissions by 60 percent, down to 150 million metric tons of greenhouse-gas emissions annually. But reaching the full 80-percent reduction will require technologies that are still in development or only theoretically possible, like simulating photosynthesis by making liquid fuel with sunlight, the scientists said.

Their energy portrait for California in 2050 rests on four essential strategies: increasing energy efficiency, decarbonizing electricity generation, expanding electrification to displace fossil fuel use, and finally decarbonizing the fuel that couldn’t be eliminated.

To start with, the panel members have calculated efficiency and electrification targets that are believed to be realistic for three large economic sectors – buildings, industry (including agriculture) and transportation. For example, buildings, whether new or retrofitted, must be 40 percent more efficient overall than they are today and must replace 70 percent of the fuel currently used for heating and hot water with electricity, which will become nearly carbon-free (see below on decarbonization of the electricity supply).  Passenger and light-duty vehicles must achieve a 60-percent increase in efficiency, and 44 percent of them must run on electricity rather than gasoline.

Together with additional targets for industry, agriculture and heavy-duty transportation, overall efficiency for electricity use should increase by 31 percent and for fuel use by 52 percent, said James McMahon of Lawrence Berkeley National Laboratory. Despite a predicted doubling of energy demand by 2050 as a result of population and economic growth plus electrification, the actual increase in power consumed will only be 56 percent, if the plan is followed, he said.

But almost all of this electricity will need to be generated by decarbonized sources of power. Several scenarios for achieving this result were described by Jeffery Greenblatt, also of Lawrence Berkeley National Laboratory.  As now required by California law, 33 percent of any energy portfolio must come from renewable resources. Three of the scenarios maintain that minimum, while supplementing it with varying amounts of either carbon-free nuclear power or power from fossil-fuel plants fitted with carbon capture and sequestration (CCS) technologies that reduce their greenhouse-gas emissions by 90 percent. An additional 5 percent of power generation would come from natural gas plants that can flexibly provide what is called load-balancing, or matching of real-time energy supply and demand necessary for preserving the grid’s reliability and optimal operating frequency.

Load-balancing turns out to play a critical role in the push for decarbonized electricity. Because wind and solar power is intermittent, a fourth scenario, in which renewables provide 90 percent of the state’s power supply, would require twice the amount of load balancing from natural gas plants, along with far more installations for generation, Greenblatt said. Consequently, maximizing renewables in a decarbonized portfolio would create more greenhouse-gas emissions than supplementing them with nuclear or carbon-free fossil fuels.

The panel members selected as the most realistic option for the future their “median scenario,” composed of renewables at 33 percent, nuclear and fossil fuels with CCS at 31 percent each, and natural-gas plants for load-balancing at an additional five percent. But given the heightened concerns about nuclear safety after the Fukushima disaster and the uncertainties about the long-term reliability of carbon capture and storage, the path of 90-percent renewables could still turn out to be one that is chosen, said Greenblatt.

If that were the case, natural-gas plants could be replaced by technologies that provide load balancing with zero-emissions, or ZELB.  This option would substantially increase the role of electricity storage by batteries, flywheels and other technologies in stabilizing the power system, although it is currently a far more expensive alternative than natural gas. Still, together with widespread smart-grid improvements that enhance the efficiency and reliability of transmission and distribution, electricity storage could significantly improve the results from the 90-percent renewables scenario, said Long.

Finally, the report looks at fuel decarbonization, which presents an even more formidable limiting factor than load-balancing for getting to 80 percent. Panel members called biofuels a “risky bet” for reaching the target by 2050.  Given currently available technologies, it is impossible to produce amounts large enough to decarbonize the state’s fuel supply without seriously affecting food prices and incurring a substantial carbon penalty from the land-use changes that would result from clearing new acreage for growing the food displaced by fuel crops, panelists said.

The group decided, therefore, to include only biomass from wastes as fuel feedstock.  But the annual tonnage of biomass wastes available in California would fall far short of what would be necessary to reach the target.  Even if in-state biomass were supplemented by imports — for example, of sugar-cane bagasse from Brazil — only one-half of the necessary replacement fuel could be produced, according to the panel members’ calculations.  And growing enough biomass in-state to make up the balance would take an astonishing 60 percent of California’s land, said Long.

So how else could California get to 80 percent?  Barring future game-changing technological developments, such as making liquid fuel by using sunlight or having cheap and limitless electricity from nuclear fusion, Greenblatt suggested a set of options that in combinations of two or more could stretch efficiency and decarbonize enough additional electricity and fuel to fill in the 20-percent deficit.

His list of alternatives include 100-percent rather than 90-percent effective CCS, 100-percent ZELB, behavior changes to decrease electricity demand by another ten percent, hydrogen fuel to replace one-third of the fossil-fuel supplies, and carbon-neutral biomass combined with CCS to produce electricity with net-negative carbon emissions and/or make liquid fuel from coal.3

If California could utilize all these options and at the same time find a way to double its supply of biomass, then it could even get to net-negative emissions, something which might be needed to prevent the most serious effects of climate change, said Greenblatt.

At present, the alternatives on his list lack certainty. Demonstrations of CCS at 100-percent effectiveness have not yet taken place, and many experts question whether enormous stocks of sequestered carbon dioxide will remain underground for centuries, as required, without significant leakage. Similarly, replacing 30 percent of fossil fuels with hydrogen remains unrealistic, given both the cost and energy supply that would be needed for accomplishing this goal. And the power of behavior change, though demonstrated in small, time-limited pilot studies, has not been tested with a representative cross-section of the population or for sufficiently long time periods.

As the panel members admitted, 60 percent can be reached with aggressive action, but the remaining 20 percent will be an extremely tough row for California to hoe. Thus, they recommend more detailed study of possible supplementary strategies, and significant support for research and development of the innovative solutions that will allow ambitious emission-reduction targets to be met.

                — By Eleanor Saunders


1. Oregon and Vermont approach this benchmark by requiring reductions of 75 percent below 1990 levels by 2050, though Vermont adds the qualifying phrase “if practicable using reasonable efforts.”  For complete information on states’ greenhouse-gas emissions targets, see the Pew Center on Global Climate Change.

2. The report will be available through the Web site of the California Council on Science and Technology once it has been reviewed and published. See also a brief review by Science Daily.

3. The term “carbon neutral” indicates that a fuel or activity does not add to atmospheric CO2, either because it emits no carbon or because another action is taken to offset any emissions that occur – for example, by preserving a forest that absorbs carbon or supporting a clean energy project that replaces fossil fuel. Although there is controversy among experts about the carbon-neutrality of biomass, one school of thought considers it carbon neutral when that biomass is a waste product. Unlike fossil fuel, which releases carbon that has been stored for millennia, much vegetation – for example, leaves or crops — has a natural cycle of carbon absorption and release as it grows and decays over the course of a year. Wastes of this sort only release what they have absorbed during that short cycle and can be considered carbon neutral, exceptng any carbon costs that may come from transportating and processing the wastes. If biomass wastes were combined with CCS, so that the carbon they contain was removed and sequestered, then they would produce energy or fuel that could be considered carbon negative.

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