Power circuitry has always played a critical role in electronics, but the increasing use of renewable energy and the need for power storage solutions could help accelerate the development of existing power devices. Why does renewable energy face challenges with storage, how could this challenge be solved with electric vehicles, and how would this accelerate the power device sector?
Why is energy storage a big problem for renewable energy sources?
The past few decades have seen an increasing amount of pressure for governments to phase out fossil fuels in favor of renewable energy sources including solar, wind, and hydroelectric. Initially, this drive towards renewable fuels primarily came from the desire to reduce global CO2 emissions that have been linked to climate change. However, the past two years have introduced two new factors that have arguably had far greater impact that any amount of climate change: money and war.
The COVID pandemic of 2020 sent shockwaves throughout the global economy which has resulted in rising living costs, increasing interest rates, and supply chain challenges. Then in early 2022, the Russo-Ukraine war saw many countries around the world cut off oil supplies from Russia, and this undoubtedly resulted in massive energy price increases (especially for those in European countries who have been dependent on Russian fuel).
Thus, the idea of energy independence has increased in interest amongst western countries, and renewable energy sources present a viable option. While the price of solar panels has significantly reduced and energy efficiencies of renewable systems has dramatically increased, they face one major challenge: power availability.
Solar panels operate at their peak effectiveness when the sun is out, and windmills operate best during windy days, and this means that energy from renewable resources swing widely each day. Worse, energy consumption in northern regions (Canada, UK etc.), is often at a low during midday and at its maximum during the night (especially during winter where heating is required). And yet solar panels are producing their peak power during the exact opposite times.
Currently, energy grids cannot store power meaning that any extra energy being generated is wasted, and it is this fact that makes renewable energy sources extremely unreliable and expensive to operate. To add fuel to the fire (pardon the pun), the unreliability of renewable energy means that no energy grid can exist on 100% renewable source, and thus require a substantial fossil fuel backup that can meet sudden energy demands.
To solve this challenge, researchers are looking at methods for creating energy storage solutions that can hold excess renewable power during peak production and feed this power back into the grid during times of low renewable output. One promising solution is to use massive batteries as they have high energy densities (meaning they take up a small amount of room compared to other energy storage solutions) and can release substantial amounts of energy quickly. But the large cost of such battery systems combined with their flammability continues to present challenges to engineers.
How electric vehicles could solve the problem
One radical idea that researchers are currently experimenting with is to utilize electric vehicles as a singular large virtual grid battery instead of large, dedicated facilities. Simply put, electric vehicles that are plugged into the mains could be designed to not only draw power for charging, but also provide power back to the mains during times of peak demand. Assuming electric charge points become more prevalent in society, and that a parked EV spends most of its time connected to the mains, this technique could solve the energy storage challenge without needing any additional investment in grid technologies or major storage installations.
To incentivize EV owners, registered vehicles using a unique serial number would meter the amount of energy going in and out of their battery for grid use, and this would translate to a tariff paid to the EV owner. Furthermore, real-time energy tariffs would allow vehicles to charge during peak power production where energy is at its cheapest and put power back into the grid when energy prices are at their highest.
While this may sound like a promising idea, the reality of such a system presents a multitude of challenges that engineers would have to face. Firstly, a real-time energy tariff system requires APIs that allow small IoT devices to request real-time energy prices whose value is determined on real-time power production. This would mean that devices storing and generating power would need to record their output against timestamps to prove that they did indeed generate that power at that time.
The second challenge is that a charging system in such a vehicle would be complex due to the need for bi-directional capabilities (i.e., push and pull power). Furthermore, EVs plugged into the system must not allow their stored energy to fall below a user defined level otherwise taking too much will not only sacrifice EV range, but also decrease the lifespan of the battery (assuming it has a limited number of charge cycles).
It is not just renewables — batteries are becoming commonplace
Even though EVs and energy storage for electrical grids are providing great strides in battery technology development, the continued integration of electronics into everyday devices is also presenting new opportunities for batteries and battery management solutions. The need for smaller devices is a particular challenge for engineers as batteries can often be one of the heaviest and largest components in a device, and thus reducing the size of the battery can significantly reduce the weight and size. But doing so reduces its overall capacity, and this directly translates into a shorter battery life. As such, engineers will be often required to develop energy saving techniques to try and minimize energy consumption as well as utilizing components specifically designed for battery operation (e.g., using a mobile processor as opposed to a desktop processor).
Laptops and smartphones are a notable example of this. Even though they are getting physically smaller and consuming less power, their battery life and processor performance continues to increase. This is only possible thanks to advancements in semiconductor technology whereby shrinking transistor sizes and reduced gate voltages results in lower energy consumption.
What challenges stand in the way of energy storage advancements?
So far, we have discussed how renewable energy sources are suffering greatly from a lack of energy storage solutions, how EVs could be the solution to renewable energy storage, and how everyday electronics are helping to improve battery technologies, but what challenges do energy storage solutions face with regards to technical implantation?
Firstly, any battery system comprised of multiple cells must ensure that charge is distributed equally. While this is not a problem for batteries with a few cells, larger systems commonly found in EVs and large-scale storage facilities can have hundreds (if not thousands), of individual cells. The resulting number of cell connectors, ICs needed to read each cell, and management algorithms can make such systems extremely complex to construct and maintain.
Secondly, batteries store energy as a DC voltage as opposed to an AC voltage which is problematic for both charging and discharging. The conversion from AC to DC and vice versa must be done in the most energy efficient manner possible to minimize energy waste. The need for a bi-directional conversion system also introduces circuitry complexities and safety concerns, especially when dealing with electrical systems that can feed power into a circuit from multiple sources (this generally requires notices at fuse boards and switches for proper isolation).
Thirdly, large battery systems used in electric grid applications will undoubtedly be dealing with large voltages and currents. Additionally, the large amount of energy being stored will not only require components able to tolerate such conditions, but safety measures must also be integrated to prevent damage to batteries. For example, drawing too much current from a battery will result in that battery overheating, and a battery that overheats carries a serious risk of starting a fire. Considering that most high-energy batteries are based on lithium, such a fire can quickly turn into a catastrophe and cause a runaway effect where nearby batteries also fail.
Fourthly, newer battery systems are implementing faster charge times by significantly increasing the charging current, and this requires power circuitry able to handle greater currents. The size of a component is proportional to the current it can handle, and thus fast chargers will undoubtedly require physically larger circuits. Furthermore, the increased current will see a greater heating effect, and this additional heat must be appropriately dealt with otherwise it poses a fire risk.
How will the energy storage industry accelerate the power device industry?
When it comes to energy storage, power devices play a critical role whether it is for charging, current switching, or cell voltage monitoring. The problems that have been covered thus far will present the power device industry with key opportunities for advancement and integration.
The first, and arguably the most important, is the need for increased efficiencies in power converters. Even if a converter is 95% efficient, 5% of a large number is still exceptionally large, and not only does this translate to wasted energy, but that wasted energy is almost always in the form of heat. For example, a 1GW battery storage facility that has a 95% efficiency will still see a total of 50MW of energy wasted through wires, components, and storage units. Even increasing the efficiency by just 1% can provide power for an additional 20,000 homes.
Additionally, governments around the world continue to pass legislation on energy efficiency requirements of consumer devices and home appliances. As such, the demand for more efficient power converters and amplifiers will also increase as engineers are forced to squeeze every extra watt of energy they can out of a design.
The constant demand for smaller devices with extended battery life and improved performance will also help accelerate the development of new power amplifiers and power converters. As previously discussed, reducing the battery size is one of the best ways to reduce the weight of a product, but this comes as the cost of reducing the battery capacity. Energy efficient processors can help extend the life of a battery, but this comes at the cost of degraded performance. Thus, the use of high-efficiency power amplifiers and converters allows for a design to use a more powerful processor as energy that would otherwise be wasted in energy conversion can instead be used for processing.
Another area that may help accelerate the development of power amplifiers and converters is the field of energy harvesters. The increased use of IoT devices in remote areas where power sources are non-existent requires such devices to generate their own power. Energy harvesters can provide this power, but the small energy sizes involved means that power converters in energy harvesters must be as efficient as possible to minimize waste.
Energy devices used in power grids will undoubtedly be involved with extremely large voltages and currents. While traditional semiconductors have been able to operate in such environments, the introduction of new power technologies such as SiC and GaN presents engineers with revolutionary modern designs with significantly greater operating voltages, higher efficiencies, and smaller designs. The combination of higher voltage tolerances and smaller physical footprint also presents opportunities for EVs and other portable high-voltage devices thanks to the reduced weight and higher power handling capabilities.
Finally, power devices involved in high-reliability scenarios (such as large-scale grid batteries) may even integrate intelligent solutions for advanced power monitoring and device protection. For example, a small microcontroller with an embedded AI processor could be integrated into a power amplifier and provide live current and voltage monitoring. Unlike traditional device protection methods, such a system could provide predictive protection and defend against abnormal behavior. This could also be used to signal to a central host of a potential problem before damage is done.
Conclusion
As the importance of energy storage and energy efficiency continues to grow, so does the importance of power converters and amplifiers. The renewable energy sector faces a major problem with energy storage, and unless large-scale batteries can be constructed engineers may have to turn to using EVs connected to the grid as a large virtual battery. Of course, such power systems will require advanced power delivery systems capable of bi-direciton energy transfer at high efficiencies all while minimizing the impact on the life of the battery.
Portable devices will need to continue to improve energy efficiency so that batteries can be made physically smaller while energy harvesters integrated into IoT designs could present power amplifiers and converters with real opportunities for growth.
Finally, the development of large battery systems used by electrical grids will undoubtedly need new semiconductors technologies such as SiC and GaN, and the large cost of such systems might encourage the use of intelligent amplifiers that can provide predictive capabilities to foresee potential damage before it has even occurred.