As of 2014, the Environmental Protection Agency (EPA) cites transportation as accountable for 26% of total greenhouse gas (GHG) emissions in the U.S., second only to the 30% of emissions contributed by the electricity sector. With the hot topic of climate change gripping the nation and the world, reduction of GHG emissions has grown into a primary focus for both industry and politics. As energy production looks to phase out the fossil fuel era through legislation like the recent Paris Agreement and the 2015 Clean Power Plan, the transportation division is facing a movement of its own.
While carbon-emitting modes of transportation include planes, trains, and ships, it is widespread automobile use that is the chief source of harmful emission. In order to cut back automobile-related pollutants, various strategies are being explored. Perhaps the most visible of these methods is reducing travel demand. This incorporates urban planning, public transportation development, and zoning so that residences, schools, and businesses are close enough to discourage frequent driving.
Another technique involves improving operating practices so as to minimize fuel use, such as driving sensibly and improved voyage planning. These strategies are beneficial because, when aligned with urban planning strategies that are being employed in many metropolitan areas, they can be implemented relatively immediately. However, the overall effects of these approaches do not reach a desirable threshold for GHG emissions, and in turn, innovation within the automotive industry has taken strides towards a sustainable future. Driven by a rise in popular demand for environmentally friendly transportation alongside federal subsidies, researchers have begun taking the next steps to a greener future.
Speed Bumps Along the Way
Proposals for fuel switching and improving fuel efficiency with design, materials, and new technologies pose great challenges for production and research but offer potential revolutionary benefits. As a contemporary, ongoing site for scientific and engineering advancement, the green car movement finds itself struggling to balance effective design with economic viability. Despite the widely respected call for emission reduction through a shift to environmentally friendly transportation, the price tags on electric and hybrid automobiles have been daunting for the average individual.
Since the turn of the century and the arrival of the first commercially available hybrid car models, such as the Toyota Prius and the Honda Insight, researchers have faced the challenge of designing and manufacturing eco-minded automobiles at affordable costs. Glancing out at a freeway, one can physically see the successes by counting the increasing numbers of Tesla, Prius, LEAF, and Volt models. However, as is the case with most scientific discoveries, each accomplishment is wrought with numerous failures. An examination of past fuel technologies and automotive invention illuminates flaws in electric vehicles (EV) and hybrid electric vehicles (HEV); and rather than sweeping them under the rug, it is crucial to recognize and build upon them.
A focal concern to the green credentials of EVs and HEVs spawns from the “well to wheel” concerns involving the production of the vehicles themselves. Whereas an EV’s tailpipe succeeds in meeting a zero (or close to zero) emission pledge, the process of manufacturing paints a dirtier picture. This is largely due to EVs and HEVs being only as clean as the energy they are required to be built with. Given this, a more accurate accounting of the environmental benefits of green car technologies can only truly be grasped when investigating the complete life-cycles of these vehicles, thereby widening the scope through which improvements must be made. From this perspective, the complexities of a transition to green transportation begin to grow.
Where We Stand
With numerable conceptual technologies set for the future, but still kept mostly under wraps, an examination of existing, available fuel designs is warranted. Look at any commercial plug-in electric car, like the popular Tesla Model S for instance, and one will find lithium-ion batteries similar to those that power a laptop computer. However, in order to generate the amount of energy sufficient to fuel a car, these car batteries employ a more elaborate series of lithium-ion cells.
Lithium-ion batteries like the one in the Tesla Model S have been at the forefront of much of the research being conducted in regards to green car technology and have been accompanied by a multitude of benefits. For one, lithium-ion batteries possess high energy density. This characteristic is what allows it to hold a charge for an extended period of time between plug-ins, an especially noteworthy feature in regards to powering an EV since charging stations are not nearly as ubiquitous as gas stations. Other benefits of lithium-ion batteries include their low-maintenance and low rate of self-discharge, both contributing to a favorable retention of charge.
The battery, however, is not without its flaws. The electricity required to manufacture and charge the battery originates, more often than not, from the burning of fossil fuels like coal or natural gas. This unfortunate truth ties back to the “well to wheel” understanding: until clean energy sources become more effective, EVs and HEVs will be held back from reaching their potential in terms of reducing overall emission footprints.
The electricity required to manufacture and charge the battery originates, more often than not, from the burning of fossil fuels like coal or natural gas
Alongside this root imperfection of existing green car technology, the financial cost of producing the dominant lithium-ion battery is a hindrance to mass production. As lithium is a relatively rare element, its retrieval and refining is costly and susceptible to political instability. Here, the challenge of balancing eco-minded aspirations with economic realism is felt firsthand. Despite such key faults as availability and price, it is important to recognize lithium as a step towards zero emissions, and inspiration for continued alternative fuel research.
Alternative Fuels of the Future
The search for effective, non-petroleum based fuel systems has brought ethanol, biodiesel, and hydrogen into the spotlight. Ethanol and biodiesel both pose exciting possibilities as they can be domestically produced from renewable plant and animal byproducts. Plus, certain ethanol blends are already readily available at select gas stations, and biodiesel is compatible with most diesel engines. Both of these play into a huge step of reducing manufacturing costs. Unfortunately, neither take GHG emissions completely out of the picture.
For many critics, hydrogen fuel cell technology provides the answer, albeit with much research and advancement to come. Hydrogen can be harvested from many domestic sources and only emits nitrogen oxides when burned, rather than harmful GHG pollutants. Fuel cell electric vehicles (FCEV) in the past have struggled with manufacturing costs and a limited hydrogen infrastructure for fueling, but current improvements have increased their cost-effectiveness.
Toyota’s Mirai model (pictured here) and Hyundai’s Tucson are set to become the first commercially available FCEVs, and recently starred in Santa Barbara’s own Green Car Show at the 2016 Earth Day Festival. Along with the FCEV models making their debut is the equally important announcement of Santa Barbara becoming home to one of California’s very first hydrogen fueling stations.
Despite sure-to-come obstacles for these alternatively fueled automobiles, it is clear that the world, and our local community, is in the midst of a revolutionary time for green transportation. With ongoing studies exploring the possibilities of sodium-ion batteries set to replace the faulty lithium-ion and grapheme car batteries, the green car movement is proving to be a long, but fruitful road towards a clean energy future.
- Featured Image: www.bbc.com/news/magazine-22001356
- Figure #1: www3.epa.gov/climatechange/ghgemissions/sources.html
- Figure #2: www.greencarreports.com/news/1084682_what-goes-into-a-tesla-model-s-battery–and-what-it-may-cost
- Figure #3: www.caranddriver.com/photo-gallery/2016-toyota-mirai-fuel-cell-sedan-instrumented-test#6