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No. 3204:
Mobility Matters

by Christine Ehlig-Economides

Today, our thoughts are about motors instead of engines. The University of Houston presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Our modern life style takes a lot of energy. Over 80% of that energy comes from burning fossil fuels ... coal, oil, and natural gas. We burn almost all our coal, and much of our natural gas, to generate most of our electricity. We don't use oil to generate electricity. Instead, we burn oil for road, rail, air, and sea transportation.

Mobility matters. The freedom to move people and goods is a necessity of modern life. The cars and trucks we drive have engines that burn fuel that comes from crude oil. Altogether, we burn about 29% of fossil fuel for farm use and for road, rail, air, and sea transportation using engines that emit carbon. Suppose we replaced the engines on farms, roads, and rail by electric motors.


Suppose the oil used to make gasoline and diesel were instead used to make electricity. In that case, rather than millions of moving exhaust pipes, emissions would come from about 100 new power plants. Hundreds of power plants already burn coal and natural gas, and these already emit nearly two billion tons of carbon per year. Additional oil fired power plants would add about another billion tons. So how can this possibly be helpful?

Geologists and engineers who understand a lot about flow in the earth work for oil and gas companies. This industry also has the skills to remove the carbon from the power plant smokestacks and store it in the earth.

Now let's think about motors. Electric car drivers love the powerful acceleration provided by the motors in their cars. Electric cars need fewer repairs and cost less to operate, but they need batteries and ways to charge them. The value of switching from combustion to battery usage will depend on which option causes less environmental damage.

If electrifying road, rail, and farm vehicles seems possible, what about travel by air and by sea? It would not be easy to plug in a jet plane in flight or a cruise ship at sea. As well, military needs for remote energy cannot rely on power plants. Perhaps biofuels from plants, algae, and seaweed can meet these needs.

There is still a lot of oil, and it keeps our cars running at a low cost; but one day, in the far distant future, oil will become scarce. A switch to electric transportation could use renewable energy to protect our freedom of mobility in the long term. For now, a switch from engines to motors could use oil to generate electricity, and it might inspire a move toward a lower carbon future.

I'm Christine Economides at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

This episode first aired on February 19, 2019.


Some additional facts may interest readers of this episode. More than 80% of the energy we use comes from combustion (burning) of fossil fuels.1 In 2017 transportation represented 29% of U.S. energy use, of which 89% came from crude oil (petroleum), and 3% from natural gas, and in addition, 5% of transportation fuel is from biofuels used as additives to gasoline and diesel fuel.2 Nearly 62% of U.S. crude oil use occurs on farms and for road and rail transportation, representing about 65% of all U.S. crude oil combustion. About 76% of the oil we use is combusted for transportation and heating, and overall 93% of crude oil is combusted for one reason or another. Less than 2% of crude oil consumed in the U.S. is used in petrochemical feedstocks.

A legitimate question raised in the episode relates to life cycle analysis (LCA) comparing transportation using battery electric vehicles (BEVs) and conventional internal combustion engine vehicles (ICEVs). Figure 1 provides information detailed by Hawkins, et al.5 This figure encourages a lot of study because it addresses many environmental concerns. The figure considers two types of battery technologies: lithium-nickel cobalt manganese oxide (Li-NCM) and lithium iron phosphate (Li-FEPO4); and specific fossil based electricity generation including a European power mix (EU) compared to natural gas (NG) and coal. The figure also considers gasoline and diesel fueled internal combustion engines. Different impact colors relate to a list of vehicle production and use attributes that apply for all of the vehicle types. To further assist the reader, following are definitions for terms found in the figure:

  • Global warming potential (GWP). GWP is a measure of how much heat a greenhouse gas traps in the atmosphere up to a specific time horizon, relative to carbon dioxide.
  • Terrestrial acidification potential (TAP). TAP is a consequence of acids, derived mainly from SO2, NOx, HCl, NH3 and HF and expressed as SO2 equivalent, being emitted to the atmosphere and subsequently deposited in surface soils and waters.
  • Particulate matter formation potential (PMFP). PMFP relates to potential to distribute solid particles, such as dust, dirt, soot, or smoke, and liquid droplets in the air.
  • Photoochemical oxidation formation potential (POFP). POFP is the potential for reactions involving sunlight and emissions from fossil fuel combustion that create smog and other chemicals including ozone.
  • Human toxicity potential (HTP). HTP is a calculated index that reflects the potential harm of a unit of chemical released into the environment based on both the inherent toxicity of a chemical compound and its potential dose.6
  • Freshwater eco-toxicity. Ecotoxicity refers to the potential for biological, chemical or physical stressors to affect ecosystems. Here the focus is freshwater.
  • Terrestrial eco-toxicity. Ecotoxicity refers to the potential for biological, chemical or physical stressors to affect ecosystems. Terrestrial means on land.
  • Freshwater eutrophication. Eutrophication is the process through which lakes, streams, or bays become overloaded with nutrient-rich water, fed by excess nitrogen and phosphorus. When this occurs, large blooms of algae and aquatic plants occur. Eutrophication can occur in both freshwater and saltwater systems, but here the focus is freshwater.
  • Mineral depletion potential. Potential to deplete minerals required for various process and material components.
  • Fossil depletion potential. Potential to deplete fossil fuels
  1. Energy Information Administration. U.S. Department of Energy. 2011. Annual Energy Report
  2. Energy Information Administration. U.S. Department of Energy. 2017. Use of Energy Explained. Energy Use for Transportation.
  3. Energy Information Administration. U.S. Department of Energy. 2018. Today in Energy.
  4. Gibbs, W. Wayt, and Andrea Gawrylewski. 2018. Autonomy: The Quest to Build the Driverless Car - And How It Will Reshape Our World. Scientific American 319, no. 3: 100-100.
  5. Hawkins, T. R., Singh, B. , Majeau-Bettez, G. and Strømman, A. H. 2013. Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles. Journal of Industrial Ecology, 17: 53-64. doi:10.1111/j.1530-9290.2012.00532
  6. Hertwich, E. G., Mateles, S. F., Pease, W. S. and McKone, T. E. (2001), Human toxicity potentials for life-cycle assessment and toxics release inventory risk screening. Environmental Toxicology and Chemistry, 20: 928-939. doi:10.1002/etc.5620200431

Chart of normalized impacts