Flywheels in Transportation Vehicles and the Energy Saved

The excessive use and depletion of fossil fuels has brought in sight that there needs to be a way to reduce the amount of fossil fuels required to produce an amount of energy. The main consumer of fossil fuels are transportation systems which is creating a big concern since the amount of carbon dioxide gas emitted which promotes global warming. Therefore, it is not just a concern but a necessity to reduce the amount of energy generated by fossil fuels.

The Flywheel is incorporated into any vehicle to increase the efficiency and hybridize the vehicle. The Flywheel is used as an secondary energy system in all vehicles including battery electric vehicles[1]. The flywheel energy storage is also combined with mechanical transmissions for brake energy recovery[2].


Figure 1 – Flywheel energy charge and discharge when braking force is applied[2]

The Energy stored in the flywheel is released to the wheel when there is an immediate acceleration required. This technology can also be used in Light transportation which is for public transport generally short distances[3]. Continuous energy is provided to the train, the train receives higher energy to charge the Flywheel near the Stations and it continuously uses the stored energy when it moves away. The train is slowly charged back to its full capacity when it reaches the next station[4]. The potential energy saving when a flywheel is added to the train is about 29.8%[5].


Figure 2 – Power flow to and from the Flywheel Energy Storage system[3].

There are several diesel-electric locomotives, which includes the position and the location of the flywheel in the long distance trains to improve the efficiency and reduce fuel consumption of the locomotive[6]. Comparisons between normal only diesel engines with motors and diesel engines with flywheel technology, this explains that the Hybrid vehicle is always better. New technologies like carbon fiber flywheels further help in increasing the speed of the flywheel for better energy storage[7]. The placement of the Flywheel also matters for trains. The best location to place a flywheel is found out. Continuous Variable transmissions are required for the flywheels to be coupled with the engine. The most important part in a flywheel system is the planetary gearbox[8].


Figure 3- The working principle of a Flywheel energy storage system in trains[9].

The efficiency saving of each car, short transit trains and heavy haul trains are found out. The total number of trains and cars currently running in the United States are combined. The total Efficiency of all the vehicles and the energy saved by the vehicle is found out. This gives an idea about the savings in Fuel, and the reduction in carbon dioxide in the air.


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Mitigation and analysis of the impact of PEVs on Grid Reliability

Vehicle-to-grid (V2G) technology is a concept of controlling/allowing the energy to exchange between PEVs and the power grid. V2G utilizations allows for PEVs to act as a load on the system or generator by using the energy stored in their batteries to enhance the grids reliability rather than creating potential overloading situations, in which supply is unable to keep up with or meet the demand loads [1]. The negative impacts of PEVs can be caused by using up the reserve capacity to power the extra loads (e.g. large penetration of PEVs fast-charging on the grid during a hot summer afternoon). The other big issue is potential congestion of the feeder lines with heavy localized PEV loads [2]. There are two categories used to classify V2G communications: Unidirectional and Bidirectional. Unidirectional communication is a one-way power flow from the grid to the vehicle, that allows the grid to throttle the charging rates of PEVs to help prevent grid overloading, instability and voltage drops [3]. Bidirectional communication allows for two-way flow between the grid and the PEV battery that is behind the meter. This provides active power support for the grid, by discharging the PEVs when peak load shaving and/or load leveling are required. Inversely, it charges the PEVs as in the unidirectional case, but provides more benefits such as increasing the feasibility of incorporating renewable energy sources as a distributed generation source by using the aggregated PEVs as energy storage when the intermittent renewable generation is insufficient and can store the excess generation when supply exceeds demand [3]. A comprehensive list of the various applications, benefits and drawbacks of these two categories of V2G can be seen in Figure 1.

V2G app from integration article

Figure 1: Detailed list of Unidirectional and Bidirectional V2G benefits and drawbacks [3]

The drawbacks will be addressed in further detail later-on when addressing the short comings of V2G implementations such as the degradation of battery life and high infrastructure costs before implementation can be effective [1].

Having the V2G capability isn’t enough to effectively improve the grid efficiency and reliability. Implementation of successful charging strategies must also be implemented, using systems called ‘smart scheduling’ to ensure that primary charging occurs during off-peak hours or that large levels of PEVs don’t overload transformers with bulk fast charging (Power draw of up to 90kW per vehicle) [4]. The general goal of smart scheduling is to charge the PEVs during low demand to prevent the extra load from harming the grid reliability during peaks in demand. Discharging the aggregated PEVs during high demand to help with power grid regulation and to ensure excess spinning reserves are still available [3]. There are two types of charging, controlled (coordinated) charging and not-controlled (uncoordinated) charging, uncoordinated charging can be detrimental to grid reliability, by allowing PEV owners to charge their vehicles at their desire. This type of charging can lead to the highest effect on peak loads of varying power systems as shown in Figure 2.

Demand impact - uncoordinated charging (impact analysis of v2g)

Figure 2: Impact of uncoordinated charging on peak demands [5]

In places like Australia and Belgium with 30% of EV penetration you can see the large impact the charging stations have on the peak loads, all due to uncoordinated charging. Meanwhile, smart charging or coordinated charging is deprived of algorithms, “Smart charging/discharging lessens daily cost of electricity, deviations in voltage, load surges in transformers and line currents” [5].

It’s important to note that PEVs can have a beneficial impact on the reliability of the grid if implemented correctly, and proper analysis of V2G and optimized charging strategies are one way to ensure it.

Note: Due to lack of completed research, I would like to add further information regarding “Fuzzy-Load Modeling” to help understand the potential uncertainty that coincides with EVs.


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Environmental Impact of Lithium-Ion Batteries

Electric vehicles (EVs) have an important role for the future; they hold a key position in saving earth from global warming to which greenhouse gas emissions from internal combustion engine automobiles contribute a lot. But the question is, are EVs enough environment friendly too. Certainly greenhouse gas emissions are not a concern when shifting to EVs but it is found that the electricity used in charging is responsible for greenhouse gas emissions as most of it comes from natural gas powered power plants [1].

It is also evident that the electricity required for charging these lithium ion batteries can come from other sources like coal based power plants in which case the environmental impact is much more as far as greenhouse gas emissions are considered. A better understanding can be taken through a study done by scholars from Carnegie Mellon University, where they have compared the generation pattern of two different regions based on their supply and demand [2].


Figure 1. Conceptual illustration of emissions associated with average generation, marginal generation, and marginal consumption[2].

The figure explains a region in which a nuclear plant is sufficient to cater its existing load, however in the other when the nuclear plant is not able to cater the need completely and if there is a marginal load of EVs, a different coal plant has to marginally meet the demand of EVs and the existing load[2].

Another hazard of the lithium ion batteries that are used in EVs is their improper disposal. The batteries can have chemical as well as physical hazards. If proper safety measures are not taken in the battery the due to thermal runaway the batteries can have rupture of cases and may cause a physical injury. It happens because of the exothermic reactions in the battery which are caused by various factors like overheating, overcharge and mechanical force on the battery. Heat dissipation in the battery plays an important role towards prevention. There are chemical hazards of the battery which can impact the environment. First is the nature of lithium metal which is flammable and reactive. If not disposed properly, the battery may release toxic materials [3].

Due to the continuous requirement of energy efficiency in them, the batteries are always under improvement based on their performance, lifecycle and    recharge ability [4]. Recycling the batteries is a very good option but has consequences associated to it. Most of the metals present in the battery can be extracted through different processes like thermal treatment and solvent extraction or their combination, but there is a possibility of them having the risk of releasing toxic gases during it which is an environmental hazard. These processes also consume energy to operate which again takes us back to environmental impact of energy generation. Alternative processes are being studied in this regard[5]


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[5]. Li J, Shi P, Wang Z, Chen Y, Chang C. A combined recovery process of metals in spent lithium-ion batteries. Chemosphere. 2009;77(8):1132-1136.  doi: 10.1016/j.chemosphere.2009.08.040.

Electric Energy Storage in Utility and Issues to Overcome in Order to Revolutionize the Grid

The increasing necessity for power generation is growing exponentially throughout the years. With the growing concern of global warming, the electrical energy storage in utility is becoming increasingly important to countries around the world. Emphasis is put on electrical production from renewable resources. Electrical energy storage will become vital for the stability of electrical generation from renewable resources. With the increased demand of power generation through renewable resources, decarbonization has also been a hot topic of many scientists and politicians alike. In order to gain support from the government for the expanded and commercial use of renewable resources and make the cost more affordable, achieving a low-carbon world is just as important as achieving stability on the grid from power generation of renewable resources. Energy efficient policies spike investor interest which in turn fund the developing technologies of electrical energy storage.

Most of the electrical power generated in the United States alone is supplied from fossil fuels. Majority of which is from coal. The generation of renewable energy used for grid applications has been increasing in the last decade. Hydro, wind, solar, and thermal energy generation for utility are grid-tied and are not stand alone renewable energy as they are intermittent energy sources. Solar, for instance, is not as productive on overcast days as it is compared to clear sunny days. Wind can be a powerful source depending on your geographical location. The Midwest has many more wind farms that generate the necessary electricity to power a portion of the grid, but that electricity cannot be carried long distance. In instances like these, when power generation is not ideal for that period of time, electrical energy storage comes in handy to cover the down time the grid is experiencing.

There are several issues this paper will focus on which will go into more detail for the lack of reliability, stability, and power quality of the renewable energy generation already in use. Each renewable resource will be discussed as what application it is best suitable for. This paper will also cover the ancillary services available to the grid that provide a variety of operations to maintain grid stability. The purpose of this paper is to inform of the renewable resources already available to the grid and the potential they provide for decarbonization of the already high concentrations of carbon in the atmosphere.


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The Need for an American Energy Transformation

As the world continues to develop there will be new energy solutions improving the way we acquire and store energy and the competition between countries will never seize. An energy transition will have a lasting impact on generations to come so it’s important to plan ahead and ensure the system is well thought out. Comparing the energy transitions across borders gives an insight into what is benefiting the overall energy grid and what could be improved. As a country, United States is developing world renowned electrical solutions yet its failing to implement them to their full potential to aid its citizens in their everyday energy needs.

Research surrounding the global impacts of fossil fuels and greenhouse gasses is growing, leading to a more carbon-conscious population. Putting more focus on renewables and improved energy systems will not only expand the growing industry and help create new, cleaner jobs but it will also improve the air and water quality for future generations. As the green energy movement gathers momentum more competition in the field will sprout up, creating more competition and more accessible green technologies. Making a country-wide effort to improve the current energy systems would put more money into the industry and quicken the research required to improve and create state of art solutions.

Not only will a country-wide transition improve the economic and environmental aspects of green energy, it will also require more research and lead to more options which will help obtain the most efficient energy system faster. It’s important to create reliable and efficient systems for the future as more natural disasters threaten to destroy or weaken our current systems. Improving the efficiency of the grid may initially take lots of money and time but in the end, it will create an energy solution that’s cheaper than the current option leading to a smaller carbon footprint.

Updating current technology will also help the consumer become more aware of their energy consumption with technologies such as electric meters and local renewables. It will bridge the gap between the consumer and the electricity they need, creating a more personal experience. With quickly developing technology, consumers will be able to control their home’s electricity from their smartphone. Putting more focus on updating energy storage and production tools will connect and simplify our needs for energy. The use of algorithms in smart grids will also improve the efficiency, potentially saving the country millions of dollars for when you forget to turn off the lights when you leave your house.

Imagining an energy transition on the scale which other countries are experiencing it will bring light to the issue. If other countries can incorporate these new technologies among their medieval castles why can’t the United States incorporate it into its vast cities and into its suburban communities? In order to meet the broad energy goals and successfully compete in the energy market, the United States will have to take on a drastic energy transformation and who else to base it on than Europe?


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