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Greene Outlines the Road Ahead to Deep Decarbonization of Transportation

Overhead view of traffic jam in a city.

Photo by Tienko Dima on Unsplash

As the earth is already 0.9°C (1.6°F) above preindustrial levels, there is urgency to achieve deep decarbonization of all sectors of the economy to avoid more than a 1.5°C rise in the earth’s temperature.

Globally, the transportation sector is the third largest source of greenhouse gas emissions, but in the United States, it’s been the largest source of emissions since 2017. While electric power production emissions have started to drop, in part due to the adoption of renewable energy, the transportation sector has a long way to go to reach targets set by the Intergovernmental Panel on Climate Change.

“Of all the simulations run to see what might be able to hold the global temperature rise to 1.5°C, they all essentially converge around the idea that we’re going to have to get net-zero carbon emissions by about 2050,” said CEE Research Professor David Greene, who is also a senior fellow of the Howard H. Baker Jr. Center for Public Policy.

Greene was recently tapped to serve as a senior research engineer to advise the administrator of the National Highway Transportation Safety Administration, and he shared his expertise on what is needed to achieve deep decarbonization of the transportation sector in a talk virtual talk for the Baker Café.

David Greene.

David Greene

Greene said that achieving net-zero by 2050 means that every sector has to drastically reduce emissions and that we also may have to remove carbon dioxide from the atmosphere.

“What goes up must come down,” he said. “So if you put carbon dioxide in the atmosphere after 2050 it will have to come down into a sink like a forest store or biomass or soils. What lies ahead is a transformation of the whole energy system, and for transportation that not a simple matter of switching out one technology for another or even just changing the price of carbon.”

Greene outlined three pillars of decarbonization: 1) improved energy efficiency, 2) use energy carriers and sources of energy that are inherently low or zero-carbon, and 3) improve system efficiency.

Deep decarbonization impacts enormously complex interconnected systems, and Greene highlighted just some of the infrastructures that will be affected, including roadways, airports, railways, refineries, refueling stations, and power plants. He said the regulations that will be impacted include everything from traffic laws to safety regulations to hazmat regulations to air traffic control.

Business models in the transportation industry will also change, including vehicle manufacturing and repair, car rentals, airlines, railroads, and more. But that’s not all. There are also lifestyle considerations, including adapting low-density living in suburbia, commuting, internet shopping and parcel delivery, vacations and business travel, recreation, recreational boating, and more.

In terms of efficiency, Greene said there’s no reason why every light vehicle could not be a hybrid with 50 percent greater fuel economy at a cost well below the savings on fuel. Beyond efficiency is the transition to zero-emission vehicles, which needs to happen in tandem with decarbonizing the electric grid.

Greene said battery electric vehicles and hydrogen fuel cell vehicles are very promising, but right now battery electric vehicles represent only one percent of the 275 million motor vehicles in the US. Fuel cell vehicles are even fewer, as they are currently only sold in California, and there are only 8,000 in operation.

Zero-emission cars need new infrastructure for refueling or recharging. Compared with about 1 million hoses for putting gasoline in cars, there are still only about 17,000 outlets for fast charging electric vehicles.

In addition to motor vehicles, Greene outlined some of the issues with the efforts to decarbonize heavy duty trucks, planes, and ships. Ultimately, he sees that society will need a range of policy solutions to help overcome the hurdles ahead.

“We’re going need a variety approaches to overcome all of the market introduction issues, the market acceptance barriers, the scale economy barriers, the diversity of choice in vehicle type barriers, infrastructure barriers, including lack of refueling infrastructure and of recharging infrastructure,” he said. “It will require determination, persistence, intelligence, and innovation, but it can be done.”

Élan Young: