What will a day in the life of a Californian be
like in 40 years? If the state cuts its greenhouse gas emissions 80% below 1990
levels by 2050—a target mandated by a state executive order—a person could wake
up in a net-zero energy home, commute to work in a battery-powered car, work in
an office with smart windows and solar panels, then return home and plug in her
car to a carbon-free grid.
Such is a future envisaged in a study published by Science
that analyzes the infrastructure and technology changes needed to reach California’s aggressive
emissions reduction goal. The study was conducted by scientists from the U.S.
Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and
the San Francisco-based energy consulting firm Energy and Environmental
The researchers describe a not-so distant time in
which lights, appliances, and other devices are pushed to unprecedented levels
of energy efficiency. Electricity is generated without emitting carbon dioxide
into the atmosphere. And most importantly—even after these measures are
implemented—cars, heating systems, and most other equipment that now run on oil
and natural gas will instead be powered by electricity.
The scientists say that all of this will be
technologically feasible by 2050 if today’s pace of innovation continues.
“This study is meant to guide decisions about how
to invest in our future. Assuming plausible technological advances, we find
that it’s possible for California
to achieve deep greenhouse gas reductions by 2050,” says Margaret Torn, the
corresponding author of the paper and a staff scientist in Berkeley Lab’s Earth
Sciences Division. Jim Williams, chief scientist at E3 and professor at the
Monterey Institute of International Studies, is the lead author of the paper.
Step 1: More than a quarter of the emissions reductions needed to reach California’s goal will have to come from energy efficiency. Sustained technological improvements are needed, however, such as the advances developed at Berkeley Lab’s windows testing facility. Photo: Roy Kaltschmidt
“To reach this goal, energy efficiency comes first,
followed by decarbonization of electricity generation, followed by the
electrification of transportation and other sectors,” says Williams.
The scientists developed this prescription using a
model of California’s greenhouse gas emissions from 2010 to 2050 that takes
into account the state’s changing population, economy, and physical
infrastructure. The model includes six energy demand sectors (residential,
commercial, industrial, agriculture, transportation, and petroleum industry)
and two supply sectors (fuel and electricity).
They explored the best ways to reach California’s goal of
reducing greenhouse gas emissions in 2050 by 80% below 1990 levels. This target
is consistent with the Intergovernmental Panel on Climate Change’s Fourth
Assessment Report, which outlines the global emissions required to stabilize
atmospheric concentrations at 450 ppm. In California, this means a sharp reduction in
carbon dioxide emissions per year from 427 million metric tons in 1990 to 85
million metric tons in 2050.
The scientists started with this 85 million metric
ton target and worked backwards to determine the changes needed to get there.
They arrived at four mitigation scenarios, all of which rely on three major
energy system transformations. Among the findings:
Energy efficiency comes first
Energy efficiency has been the low-hanging fruit for decades when it comes to
reducing energy demand, and will likely remain so. The scientists found that
energy efficiency improvements will net 28% of the emissions reductions
required to meet California’s
goal. The catch, however, is that energy efficiency will have to improve by at
least 1.3% per year over the next 40 years. This is less than the level California achieved
during its 2000 to 2001 electricity crisis, but it has never been sustained for
The scientists found that the largest share of
greenhouse gas reductions from energy efficiency comes from the building sector
via improvements in building shell, HVAC systems, lighting, and appliances.
Next, decarbonize electricity generation
Another 27% reduction in emissions comes from switching to electricity
generation technologies that don’t pour carbon dioxide into the atmosphere.
Renewable energy, nuclear power, and fossil fuel-powered generation coupled
with carbon capture and storage technology each has the potential to be the
chief electricity resource in California.
But they all must overcome technical limitations, and they’re all currently
more expensive than conventional power generation.
Because it’s unclear which technology or
technologies will win out in the long run, the scientists developed three
separate scenarios that emphasize how each can reach the target, plus a fourth
scenario that includes a blend of all three.
In addition, they determined that Californians
can’t rely on renewable energy alone. At most, they found that 74% of the
state’s electricity could be supplied by sources such as wind and solar. The
scientists also stressed that a renewable energy-intensive grid will require
breakthroughs in energy storage and ways to enable smart charging of vehicles,
among other technologies.
They also found that 15% of the required emissions
reductions could come from measures to reduce non-energy related carbon dioxide
and other greenhouse gas emissions, such as from landfill and agricultural activities.
And 14% could come from various unrelated technologies and practices such as
smart planning of urban areas, biofuels for the trucking and airline industry,
and rooftop solar photovoltaics.
And finally, goodbye gas, hello electrons
Even after these emission reduction measures are employed, the scientists still
came up short in ensuring California
meets its emissions reduction goal by 2050. So they turned to cars, space and
water heaters, and industrial processes that consume fuel and natural gas.
They determined that most of these technologies had
to be electrified, with electricity constituting 55% of end-use energy in 2050,
compared to 15% today. Overall, this nets a 16% reduction in greenhouse gas
emissions, the final push needed to achieve an 80% reduction below 1990 levels.
The largest share of greenhouse gas reductions from
electrification came from transportation. In the study, 70% of vehicle miles
traveled—including almost all light-duty vehicle miles—are powered by
electricity in 2050.
“The task is daunting, but not impossible. California has the right emissions trajectory with
Assembly Bill 32,” says Williams, referring to California’s 2006 emissions legislation. “And it isn’t a matter of technology alone. R&D, investment, infrastructure
planning, incentives for businesses, even behavior changes, all have to work in
tandem. This requires policy, and society needs to be behind it.”