Is There a Low or Zero Emission Vehicle in Your Future?

Bill Tumas
Los Alamos National Laboratory
 

Since the days of Henry Ford and his first assembly line, the automobile has had a tremendous impact on our lives. Transportation drives our economy and our way of life. We may or may not be traveling in the flying cars forecasted by some people for the 21st Century. But the automobile and our transportation system in general will see significant changes over the next two decades.
 
Changes to our transportation system will not come easy. The internal combustion engine and our transportation infrastructure, including car manufacturing, gasoline production and delivery, and our roads and interstate system, have had over a hundred years to develop. The planet has been blessed with staggering amounts of stored solar energy in the dinosaur carcasses and prehistoric biomass that have transformed over eons into petroleum, natural gas, and coal, which we call fossil energy. Even at its peak prices last summer, gasoline was still cheaper than the bottled water or soda that you may have bought at the gas station when you filled up your car.
 
The benefits of the automobile and fossil-energy-based transportation have not come without a complex set of problems. It is clear that continuing business as usual will have significant impacts on our economy, the environment, and our national security. In the last four decades, we have had three “energy crises” in the form of oil shortages and high prices. Yet the US still consumes about 22 million barrels oil each day, of which about 60% is now imported, largely to power our more than 250 million vehicles. We are digging up and using the Earth’s stored solar energy at an astounding rate. Decreasing our reliance on foreign oil is critical to our national and economic security.
 
Burning all this fossil fuel for transportation has significant environmental impacts as well. Air pollution and smog from the nitrogen oxides and particulates from automobile exhaust were big issues in the 1960s and were largely mitigated through regulations and the development of the catalytic converter. But today we are faced with how to deal with carbon dioxide emissions that can cause global warming. About a third of the carbon dioxide emissions in the US come from transportation. Imagine how these problems will be exacerbated as the developing world, particularly China and India, start driving cars the way we do.
 
Policy makers, investment bankers, and manufacturers, as well as scientists and engineers, have been actively trying to understand the range of options available to power our transportation system. The objective is to develop a secure, sustainable, carbon-neutral way to fuel our vehicles, with benefits to our economy and the environment. Near-term and long-term solutions are being sought. A number of options are being actively investigated. They include efficiency increases through hybrid vehicles, advanced fuels derived from biomass, unconventional fossil fuels such as shale oil, direct storage of electric energy in batteries for electric or plug-in hybrid electric vehicles, and hydrogen.
 
All of the options under consideration have very interesting political, social, economic, and technical issues associated with them. For example, biofuels, particularly ethanol from corn, have raised the food versus fuel debate. Hybrid vehicles increase gas mileage significantly but still require fossil fuel. Electric driven vehicles have issues that must be overcome with overall driving range, battery capacity and costs, and the impact of a large number of electric vehicles on our aging electric grid. Hydrogen has issues associated with overall costs, infrastructure for transmission and delivery, and on-board storage capacity. There may be no single best solution. We will likely need to develop and implement a combination of fuels and technologies over a range of time frames to transform our transportation system.
 
Hydrogen powered vehicles using fuel cells offer one potential solution to the transportation dilemma. Fuel cells convert chemical energy in the form of hydrogen and oxygen directly into electricity with water as a byproduct. The energy conversion process using fuel cells is about twice as efficient as that for an internal combustion engine. Los Alamos National Laboratory has been working on hydrogen and fuel cells for over thirty years and is responsible for some of the key discoveries that are being applied in current technologies and prototype cars. Significant advances have been made, but further developments are still required for widespread implementation of a hydrogen-based economy for transportation. Advances are still needed to reduce the overall cost of fuel cells, which currently use expensive platinum catalysts in their electrodes. Hydrogen itself is not an energy source, but a carrier of energy. You cannot mine or drill for it, so you must make it. One of the appealing features of hydrogen is that it can be made from a wide range of energy sources including renewable energy; however, less expensive, more energy-efficient methods must be developed for its production. An infrastructure will also need to be developed to deliver the hydrogen to fuel the vehicles. Another issue is that hydrogen is not as dense on a volumetric basis as liquid fuels. So many researchers, including those at Los Alamos, are working to develop methods to store a sufficient quantity of hydrogen on-board a vehicle to allow for long driving ranges.
 
This Café will discuss the options for carbon-neutral, low emission vehicles and how much our transportation system could and might need to change. Will we all be driving cars powered by quiet fuel cells that emit only water and are powered by hydrogen generated from renewable energy? What other carbon neutral, low emission alternatives to petroleum such as plug-in electric hybrid vehicles or biofuels should we be also be considering?