Prof. Abdennaceur Karoui

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Last Updated: Friday, 30 December 2022 21:50

Energy Conservation and Renewable Energy in the Transport Sector

If we want a sustainable world, and righteously we do, then certainly future transportation will have to rely on technologies that take in consideration energy conservation and the use of alternative energy sources. In that regard, photovoltaic powered lightweight and hybrid cars will be our best bet. Cars used for commuting will no longer be four-wheel drive, SUV, or even the sedan that we know. The weight of future cars will be minimized and the energy the car uses will originate from a mix of many energy sources on board of the vehicle. Also the future will not be for battery powered cars designed with the weight, size, and luxury we are familiar with.

What currently exasperates the transportation is the use of cars for personal transportation, where single rider has become the dominant way for mobility. While cars insure personal freedom and increase one's choices, they do increase the productivity. However, a car is not only costly for both micro- and macro-economics, it induces enormous losses. At least 93% of the transported weight is essentially of the vehicle and less than 7% is of the rider (e.g., average rider weight 100kg, average for US adults, versus a car body weight of 1320kg for a sedan style, 1520kg for mid-size, and 2180kg for SUV cars). Additionally, the often oversized massive wheels require an immense amount of energy to overcome their inertia and the enormous friction with the road. Clearly, the energy efficiency of a car is extremely low and the utilized amount and variety of materials to build a car are excessive, when we know that much of the natural resources are being depleted.

Impacts of "Single Rider Car" on Individuals and the Society

Today, cars are not only extremely useful for mobility, but rather are "a must" for doing our daily business. They provide full independence for the owners; which is initially meant to be for a better time management and flexibility.  Sadly, with that independence comes many negative aspects. Cars shield people from their kids, family, and everybody else. While, today, cars improve individual’s well-being, they do degrade familial and social relations. Older generations know that fact very well ! After decades of driving, one realizes how profoundly driving alone everyday could isolate and separate the individual from the world. Cars confine people, particularly those who ride alone, in a world of solitude and selfishness. This view is neither surprising nor intended to tarnish what we view as the most valuable asset. The car is consider so, not because it is a significant investment one does during lifetime, but essentially because it is extremely useful for daily business in such a dynamic world. Obviously, the economics are driving people to often move and to move quickly, and the car appears as the only way to make it work. Cars are badly needed for daily life and without it one can’t survive, or so we are convinced. But relations with family members, time spent with the kids and others... are what make good and happy citizen, and a healthy society. Single rider cars seem to break all these good relations as well as the family bonds. Furthermore, it is well known that many arrive to their work place with a lot of traffic related stresses. It is also well known and scientifically documented that people suffer severe health degradation and weight gain subsequent to years or decades of driving.

The popular culture, developed in the second-half of last century, made us adopt individual transportation and, sadly, the developed transport infrastructure has strengthened that idea in our minds. These made us believe that there is no other alternatives, but to own a car and to work hard to pay the car loan. No, there are alternatives! First, let's not forget that going from point A to point B should not be necessarily by riding one’s own vehicle. We do know that each trip is very expensive for the individual’s economy and in terms of consumed energy. We feel that at the gas station, and when we receive the monthly bill to pay the car loan. Unfortunately, we quickly forget these pains and the money we spent, and we accept whatever is available to us, simply because the system does not offer alternatives. Sadly, plans for alternatives seem remote, even though we are running towards crisis. However, where public transportation has not been developed, people are forced to own cars to go to work, shopping...

The above controversies and many similar related to the car usage, show once more that in the future we will be forced to leave the now popular "Single Rider Car" as a minor transport solution, and cars will be in general only utilized in critical cases and situations.

The eternal question that will remain is: is the transportation in metropolitan areas and even in suburbs the problem of individuals? In my opinion, making transportation as the individual's responsibility is a wrong concept, and we are paying dearly for adopting it...  I believe, it is time to think community, public transportation.... It is time to refrain from using big cars for commuting and to abolish the dominant idea of “to have a good life, I must have a car”. That is absolutely untrue!

Alternative Perspectives for a Sustainable Transportation

The author strongly believes that there should be an entire revolution in the transportation technologies. This view is supported by many factors, including, energy and materials conservation for sustainability, reduction of traffic, control of pollution, reduction of dust generation, elimination of noise, improving public health, reclaiming parking spaces, etc. Real life data shows that the overall efficiency of current gas powered cars is only ~6%, and a trip on a car costs 8 times more energy than on electric train. Evidently, the wasted energy is huge, and so are the materials! 

Therefore, it is time to start implementing viable solutions in a hope to find our way out before the oil and gas run out. It is time to draw a technologically promising path on which we can depend on in the near future. There is no doubt that electric trains, friction-less metros, electric buses (tramways)… are the ultimate solutions for transportation. These are the most efficient technologies that reduce the energy consumption per capita, and most importantly, they are prone to be powered by renewable energy sources. Trains and horizontal railways are built to provide the least friction per passenger or per kilogram of transported fret. In addition, they allow substantial control of the pollution. Such high throughput, high efficiency vehicles can draw needed energy from the rail itself, hence there is no need for overloading the electricity grid or building dedicated ones. The grid for these trains can be directly connected to small solar power plants or wind mills along their path. Distributed renewable energy sources can increase the overall efficiency. It is so, because control of the exact amount of needed energy can be achieved, while the energy source feeds directly the vehicle. Hence, there is no need for large intermediate devices and systems, namely, energy transport grid over long distance, electronics that adapt the motors to the sources, electronics for energy management, and large batteries for storage. Even if the primary energy source was hydrocarbon based, these electric trains and the like remain the most useful and economic, and their aggregation allows pollution control. The technology could be the least invasive to the environment, because power plants have the benefit of being in one spot, where emitted gases could be efficiently processed. It is true that the process will cut a piece from the produced energy, but that trade-off is a must to ensure a cleaner environment. In the contrary, gas powered cars and trucks, and planes for that matter, spread emitted gases all over. They are inherently polluters, with no possible economic solution in the horizon.

Historically, strong research on batteries got to speed at the same time as photovoltaics (PV), because both have the same concern (energy) and some photovoltaic cell designs utilized the same route to harvest solar energy as batteries (i.e., electrochemistry). The two have achieved tremendous progress. Scientists did an excellent job, but they could have done better, if funds were enough, and if utility companies (not oil companies) have not pressed on the breaks. In any case, PV, concentrated PV (CPV), concentrated solar power (CSP) plants, and wind energy technologies are taking off and will be used to power trains over thousands of miles without the need for energy transport across the country. As for wind energy technologies the industry has reached maturity quickly (because they are much easier and are not as high tech as PV, or Solar windows…). Though the wind energy potential is much more limited than solar, they still constitute a huge renewable energy source suitable for powering trains. In fact, PV and wind technologies go hand in hand because of the weather thus must be utilized in a way to complement each other. When combined, they form a really robust solution, and they promise a truly sustainable and economic transportation. They are coming to earnestly power our trains, buses, metros…and everything else. Solar and wind technologies are reliable and doable, truly, as long as we adjust our habits; that is increasing our daily activities and reducing energy consumption during night time so to avoid energy storage (e.g., electric batteries)! Note that CSP is the alternative to electric batteries; it offers the benefit of storing the harvested energy, in top of its main function as solar energy harvester. Apparently, it is more promising than electrochemical batteries [1], whether it is the thin-film lithium batteries (adopted by most companies like Tesla), or the new ultra-fast charging Li-polymer batteries [2] 3D graphene-based batteries [3], newly designed all solid state batteries. Although technology will be mature no later than five to ten years from now, it does present greater hope than batteries, at both levels, energy efficiency and pollution.

In summary, the scheme of large scale utilization of friction-less and friction-least vehicles will prepare the stage for future technologies, after the oil era. It supports the concept of public transportation serving large communities, while it will help abolishing the now popular practices of "Single Riders" and "Massive Cars" and will cure their isolating effects and detrimental consequences on our environment.

Why Electric Car Technology is still good?

Two reasons for tolerating electric cars, though they are now costly and inefficient, both in energy and materials (batteries). The first is “tactical” and is technology related. Though electric cars consume 2.5 more energy than electric train, and 1.5 more than the metro, they offset the pollution problem created by voyagers who are addicted to driving. Most important, these electric cars can adapt to the changing economic factors and the increasingly stringent sustainability requirements. On the one hand, future electric car design could, indeed, evolve towards much smaller and lightweight and thus more energy-efficient vehicle with a huge reduction in materials. On the other hand, expected innovations in electric cars will be assets for many other technologies. The second reason is strategic and is similar to that permitted the extraordinary development of the personal computer and thereafter the smartphone. Reaching the consumer acceptance, in first place, is essential for increasing the investment in this technology, thereby permitting its improvement. In its future development electric car will be lighter and hybrid; its progressive development will depend on the consumer acceptance and taste for new and "cool" technologies.

It seems that electric cars can survive the market thanks to special programs to which huge incentives are allotted, some special demands among the consumers, in this case younger generations, and the people desire to reasonably support development of new technologies. But for this to really succeed, it is essential that automakers develop proper technologies that are sustainable, before the federal tax credit run out. The US federal program offers a nice package of $7,500 to the buyers; however, the program limits the number of vehicles for each automaker to 200,000. It is foreseen that the real price of presently designed electric cars will inevitably increase significantly. In the event the energy gain and sustainability factors appear negative, which will most likely to happen with the design being released, the whole effort will quickly vanish. Therefore, smarter design of future cars, lighter vehicles, use of photovoltaics and/or fuel cells, reduction of the role of batteries, energy efficiency of each element of the car, etc....  and reduction of the vehicle cost must be seriously considered by automakers to keep the technology alive and ultimately produce sustainable vehicles. The success of cell phone technology was only possible through miniaturization, lightweight devices, maximization of the functionality of every part, and elimination of the clutters. The concept of designing massive cars, in particular those used for commuting, with unnecessary functions will not lead to designing future cars. 

Exceptional Use of “Battery powered truck”

just compare the energy consumption (joule/meter) of electric cars to that consumed by electric trains in the given chart. This infers that the “Battery powered truck” will not be popular, as electric trains are much more energy-efficient for fret transport. Even though, one must recognize the innovators for being true movers and shakers; their initiative is opening the gates for new technologies. At this turning point, where energy, pollution and sustainability are the central issues, the world needs technology enablers who endeavor solving the big challenging questions. We cannot just sit and watch the legacy offering routine and failing products, and using high-tech (like photovoltaics, or batteries) to sustain unsustainable technologies (like national power grids, don't confound with the modern local and micro-grids).

The “Battery powered truck” technology can still be used in some specific niche applications, maybe in airports but certainly indoors; for instance, inside large warehouses, large clean production lines, or underground infrastructures, where pollution is not tolerated and where railways, transport belts and the like cannot be utilized. Nonetheless, the niche market will remain small and only for critical cases; thus, it will neither solve the energy nor the environmental problem caused by transportation, as the problem of gas emission by vehicles will be substituted with battery pollution. Since the gas emission at the electricity production source will remain, production and use of batteries will worsen the pollution.

The big question associated with trucks is: Why do we need to preserve the concept of "trucks for transporting fret"? A side from convenience, manageability, and scheduling flexibility, trucks generate a host of energy and pollution problems, compared to electric trains, that can no longer be sustained. As noted above, instead of preserving legacy technology and its hardware, and instead of going into wrong innovative technologies that have not much chances to survive and that lead to wasting materials, let's use the money to improve photovoltaic technologies!  New photovoltaic concepts are promising to double current cell efficiency. That will be more than enough to install a paradise on earth. Let’s not forget that the sun is an "infinite" source of energy; it is a matter of knowing how to harvest a tiny portion of the energy impinging earth surface, to improve our quality of life. We are not there yet, but research on the most abundant and friendly semiconductors (silicon, and silicon-germanium alloys) and silicon solar devices offer a sound hope to solving all the above problems. Large scale silicon photovoltaics is flourishing, and better silicon cells are coming. There are strong reasons to be confident that our future industry and our needs will be driven by such durable energy sources!

Predicted Transport Technology Trends

As discussed above, the currently offered electric car models will most likely not win their case. Henceforth, automakers will have to come up with lighter and hybrid small cars! As for consumers, they need to stop dreaming of luxurious and energy-intensive cars, and better if they re-educate themselves to use public transportation.  The majority knows that electric cars have artificial prices, which will not last, and so will the gas based cars and our addiction to it.

transportation, with all scales of electric trains and speeds. As a consequence, topology of cities will transform to more star-like, or grid-like with nodes (akin of neuronal network).

Lightweight hybrid cars will be widely adopted, to bridge the gap between train stops. The lightweight hybrid cars will be powered by reconfigurable photovoltaic modules, pedals, and small batteries; the sole purpose of these batteries being to store and recycle energy excess. The lightweight vehicle itself can be designed to be recyclable, thus this trend is robust and will be sustainable.

Conclusion

With all the problems of energy scarcity, materials unsustainability, roads, parking spaces, social problems, economic aspects, car-induced health degradation,... we reached a point where we need to have a hard look at the transportation root problems and find true solutions. Why now? Because we have almost exhausted our natural resources and profoundly have damaged our environment. Our chance for survival is shrinking every day.

As these realities become more apparent and we discover that our resources have become extremely limited we will have to re-educate ourselves to save what is left. Without such a critical look, mankind will be doomed. To save home earth, we must forget about cars, at least as they look now, and we must develop robust public transportation powered by electric lines (not batteries) that are economic in terms of energy consumption and utilization of non-abundant materials. It will warm our hearts to have people back, riding together the same vehicle, as we used to do few decades ago.

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[1] Thanks to the latency of dissipation of stored heat during the day. The technology allows for at least 6 hour heat storage, depending on the design. This is excellent for powering a city at night. That cancels the need for large electric batteries. The salt and other compounds used for heat storage are not dangerous, and do not represent pollution risks; CSP is another reliable technology for the future.

[2] N. Lia, Z. Chena, W. Rena, F. Lia , and H. M. Chenga , Flexible graphene-based lithium ion batteries with ultrafast charge and discharge rates, PNAS, 109 (43) ,  17360–17365 ,  (2012).

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