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Getting to Net-Zero Emissions: A Q&A with Stanford Experts


Demand for air travel, one of the hardest parts of the economy to decarbonize, is only expected to increase in the coming decades. 

Jul 2, 2018


In order to halt climate change, major infrastructure critical to world economies will have to change. Some transitions will be smooth, such as increasing energy efficiency, which not only reduces carbon emissions from energy production, but often reduces costs. Other major industrial sources of carbon emissions, such as air travel, shipping, and cement and steel production, which make up roughly 30 percent of global carbon emissions, will be much more difficult to clean up. However according to a new review in the journal Science, there are many emerging technologies which may hold the key to addressing these tough barriers to a clean energy future.

We spoke with experts Chris Field, Director of the Stanford Woods Insitute for the Environment, Katharine Mach, Senior Research Scientist at Stanford’s School of Earth Energy and Environmental Sciences and Joseph Stagner, Executive Director of Stanford’s Sustainability and Energy Management Executive Office, who co-authored the review on what they learned and how the world can hope to tackle these daunting challenges

After reviewing all of these approaches to decarbonize the energy system, what surprised you?

Field: When I look at the options for non-emitting energy systems, it amazes me that we are still digging fossil fuels from the Earth and releasing the waste products into the atmosphere.  The exciting concept that takes center stage in this analysis is interconnecting the electrical and chemical sides of the energy system, especially through electrolysis and fuel cells.  If we can make that cheap, all of the other problems fade into the background.

Stagner: I was pleasantly surprised at how easy and fast, and economic, a transition to clean electrification can be achieved for a small city like Stanford University, and therefore is also possible elsewhere. When we started the search for sustainable energy systems for the university, we had no reason to hope that we could do it so simply, quickly and economically as we did in just five years from concept to system operation. 

Why do you think it’s important to focus on the hardest parts of the energy sector to decarbonize, such as airplanes and shipping?

Stagner: The most difficult challenges can take the longest to solve so we should start as early as possible.  Air travel, shipping, and long haul trucking are growing rapidly as society increases its mobility and the way goods and services are delivered change.  It is therefore imperative that we attack these challenges head on as soon as possible.

Field: We are making great progress in the technology for the first stages of the transition to zero emissions.  We need to be going faster but the technology is not holding us back.  When we look at the hard to decarbonize parts of the energy system, there are major unsolved technology challenges.  To complete the transition, we need to tackle both the non-technology challenges that are slowing progress on the easy parts while also working hard on the technology issues that need to be solved before we get serious about the hard part.

Mach: It’s essential to consider hard-to-decarbonize energy services now for a few different reasons. First, demand for these services, ranging from air travel to cement, is going up, not down. Second, developing technologies doesn’t happen overnight, and once energy infrastructure is in place, it lasts for a long time. Keeping the end-game energy system in sight now can help make sure we are on a successful decarbonization trajectory.

Which of the technologies holds the greatest promise for making a meaningful difference to the world’s global carbon emissions?

Mach: There isn’t a single magic bullet in addressing carbon dioxide emissions. We look at a whole range of options, for example powering long-distance transport with hydrogen, synthetic hydrocarbons, or direct solar fuels. It’s critical that we integrate different parts of the energy system and also industrial manufacturing more than at present. Together, such options and integration can push towards an energy system with vast amounts of inexpensive emissions-free electricity, ways to make sure it is available at all times and alternatives for fuels and manufacturing.

Is cost or political will a greater barrier?

Field: Both. We need research, development, and deployment to fine-tune the technologies and make them cheap. We need clear and consistent incentives to stimulate the research, development, and deployment.  We also need to look hard at features of the energy system that tend to lock in legacy technologies. Features like the diffusion of technical skills, the availability of financing, or the date a state has its presidential primary can play large roles in the pace of change.

Mach: We can go a very long way with technologies that exist and are increasingly cost-effective. What we consider here, by contrast, is the technologies that may be critically important for the decades ahead, but for which a lot more barriers exist. These barriers, important to overcome in enabling a zero-emissions energy system, include steep costs that need to be driven down, dead ends that could limit future decarbonization, and interconnections across energy services that we need to build.

What should local energy and sustainability managers be thinking about to reach lower carbon emissions?

Stagner: First, carbon emissions must be eliminated, not just reduced.  This end goal should be made clear so that we can skip unnecessary and detrimental steps in the process of assuring our survival in a hospitable world. Second, the fastest and cheapest path to the elimination of carbon emissions is clean electrification, not carbon capture & storage nor sustainable hydrogen production and use. Long haul aircraft, ships, and semi-trucks may be the exception where sustainable hydrogen or other forms of energy storage of adequately high density are the only practical solution unless and until electricity storage technologies achieve the density needed to support these modes of transportation. Third, there is no free lunch to avoid the real work required to transition humanity to sustainable energy systems,such as replacing the nations thousands of gas stations with fast electric charging stations for vehicles.  Fourth, deploying more distributed carbon-based energy systems, including natural gas ones, is death by a thousand cuts to efforts aimed at eliminating carbon emissions and should be stopped now where competitive clean electrification options are available.No new natural gas based energy systems should be deployed as a ‘step in the right direction’ away from coal or oil as they will just have to be replaced in the future with clean electrification technologies.

The review was led by researchers at many different institutions including the University of California, Irvine and the Carnegie Insitution for Science.

Author affiliations: Chris Field is the Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies, the Perry L. McCarty Director of the Stanford Woods Institute, professor of biology and of Earth system science and senior fellow at the Precourt Institute for Energy.Mach is director of the Stanford Environment Assessment Facility at the Stanford Woods Institute for the Environment, Senior Research Scientist in Earth system science, Adjunct Assistant Professor at Carnegie Mellon University, and a Visiting Investigator at the Carnegie Institution for Science. Joseph Stagner is the Executive Director of the Sustainability and Energy Management Executive Office at Stanford.

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