Vehicle-to-Grid Technology: Engineered to Enable the Smart Grid

Source: VisualMarketplace/stock.adobe.com; Generated with AI

The automotive industry is increasingly moving to electric vehicles (EVs). Though not without environmental drawbacks, EVs address climate change directly by removing inefficient combustion of hydrocarbon fuel and are better suited to adopt advanced sensor technology for autonomous driving. To maximize the environmental benefits of EVs, we must also shift to renewable energy sources. Renewables, led by solar and wind, are intermittent: the sun isn't always shining, and the wind doesn't always blow. Engineers are developing solutions to collect intermittent renewable energy, store it, and deploy it consistently for end users. One of these solutions is the smart grid, a digital network consisting of hardware and software components; power generation, distribution, and consumption infrastructure; and communication technology.

These smart grid technologies aim to deliver electricity as close to on-demand as possible without overproducing electricity. Due to its importance in the world's decarbonization effort, the global smart grid market is expected to grow from $43 billion in 2021 to over $103 billion in 2026 at a compound annual growth rate (CAGR) of 19 percent. [1]

However, a technology gap in smart grid adoption exists, resulting from the need to shift from a grid built to deliver hydrocarbon power to one that can handle renewables. In addition, maximizing energy usage while meeting compound energy demand growth will require bidirectional power flow to and from the EV.

Figure 1 shows the smart grid's key elements, including vehicle-to-grid (V2G) charging technology, which enables ultra-high energy efficiency.

Figure 1: V2G components for EV charging. (Source: petovarga/stock.adobe.com)

V2G technology allows EVs to communicate with the power grid and to deliver and receive power on demand. This flexibility significantly benefits decarbonization and energy resiliency. The V2G unit, a power inverter that directs power to the desired application, is a novel smart grid technology enabling bidirectional power flow.

This article reviews V2G technologies that enable the smart grid and leverage EVs as mobile power sources and sinks.

What Is V2G?

V2G technology (Figure 2) is a groundbreaking way for EVs and smart power grids to partner for efficient energy flow. Power can flow to and from a source, with V2G technology acting as the valves that control delivery based on need. Power can flow from devices with high levels of available power to those needing charge. V2G technology enables the EV to act as a portable energy storage station, physically bringing auxiliary power for the ride.

 Figure 2: V2G technology enables EVs to reroute energy from their batteries to the power grid, helping to stabilize the grid and support renewable energy integration. (Source:Naeblys/stock.adobe.com) 

Role of V2G in Smart Grid Stability

The existing electrical grid was built for unidirectional energy flow from the power station to end users. Matching the power supply with the demand load curve is challenging. With a finite number of power stations, operators have historically generated excess power to avoid outages. In addition, energy efficiency is critical to modern power systems, spurring operators and consumers to optimize energy use to reduce costs and improve efficiency.

Smart grids and V2G enable energy reuse: a high energy demand draws in energy from other sources and then sends any excess back to the grid when demand slows. If a portion of the grid is down, the V2G system can sense it and draw power from remote sources (in the form of nearly one billion global vehicles) to stabilize the grid.

Smart grid technology consists primarily of a grid capable of bidirectional power flow, smart meters, and other home features to report diagnostics and protect security. It also includes two-way communication support to enhance and automate energy utilization to match the load curve more closely.

Demand Response Services
The "smart" in a smart grid energy distribution network is the digital control. When an application needs power, the V2G unit directs power there until it is no longer needed. The V2G unit acts as the brain of smart grid technology, optimizing power usage and minimizing consumer costs. This demand response enables dynamic energy pricing for consumers, incentivizing usage at non-peak times. Peak shaving during energy demand plays a pivotal role in grid stability.

Renewable Energy Integration
V2G technologies are essential to integrating renewable energy into the grid to maximize usage. Wind and solar are intermittent energy sources and can lead to power fluctuation, whereas V2G can store energy in the car when more power is needed. When there's a lack of energy, the car can discharge the stored energy back into the grid. Through collaborative efforts between energy providers, users, and public agencies, V2G technology and renewable energy integration can effectively contribute to developing a more sustainable and resilient energy system.

Intelligent Charging Algorithms for V2G Peak Demand Management

Enabling electricity flow between the grid and an EV begins with a bidirectional inverter that can convert both AC grid power into DC vehicle battery power and DC to AC. This bidirectional transmission creates new opportunities for managing energy storage and delivery and incorporating renewable energy. For example, the grid can store excess energy from renewables during the day and transmit it when needed, even at night or during blackouts.

V2G systems rely on smart charging algorithms to decide when and how much EVs should charge or discharge their batteries. These algorithms account for factors such as condition of the system, energy price fluctuations, condition and average rate of renewable source energy, and EV battery voltage and charging rates.

Honest consideration of these factors enables system designers to develop power transmission timelines that satisfy EV charging and discharging schedules. This can alleviate the demand on the electricity supply, prevent blackouts, and lower battery-charging costs for EV owners during off-peak hours.

Employing smart charging protocols can increase the effectiveness and impact of V2G models by balancing the demand for electricity while aiding in the integration of renewable power supplies.

Cost Savings for EV Owners

"Recycling" generated power between consumer devices trims energy demand peaks, allowing energy companies to better predict cost through a more consistent demand profile. This peak trimming can save consumers up to $870 per EV per year. [2]

Intelligent charging can also extend the lifecycle of EV batteries by controlling how they are charged and discharged to produce less strain. This benefits EV users by reducing the necessity for fresh batteries and contributes to promoting an environmentally friendly transportation network. Batteries need to maintain a charge between about 20 percent and 80 percent for peak efficiency, and V2G enables better control over the charge levels. Additionally, intelligent charging conserves surplus wind and solar power and enhances grid resilience by addressing energy supply inconsistencies.

V2G Technology and Smart Grids

Artificial intelligence (AI), machine learning (ML), advanced sensors, and wireless communication protocols are essential in advancing V2G technology and enabling smarter and more efficient grid systems.

AI and ML Integration to Enhance V2G Systems

As engineers develop increasing numbers of technologies capable of adopting V2G, AI and ML can further improve smart grid performance through automation and predictive demand modeling.

The grid offers massive data for AI to consume. AI and ML algorithms can analyze EVs' battery health, grid conditions, electricity pricing, and EV usage patterns. Changes to the data are incorporated into the AI software and considered the next time a prediction is needed, offering continuous improvement in energy efficiency. AI can also enhance self-driving features with power management for additional efficiency.

This continuous optimization further balances the grid, lowers electricity costs, and prolongs battery life—the highest component of an EV's cost. Furthermore, AI and ML technologies can analyze trends in renewable energy production, adjusting it dynamically throughout the year. By utilizing excess energy storage capacity, these technologies can optimize the integration of renewable energy into the grid, ensuring a more stable and reliable energy supply.

Wireless Communication Protocols in V2G Technology

Another essential part of V2G technology is wireless communication, which promotes data exchange between three critical elements: the grid, the EV, and the charging station. Like AI and ML, data management aids in controlling the two-way power exchange and management of system performance.

V2G systems use wireless communication protocols to collect data on vehicle ID, battery state of charge, temperature, EV speed, metered power flow, grid frequency, and more. Each of these protocols—Wi-Fi®, dedicated short-range communication (DSRC), and cellular vehicle-to-everything (C-V2X) networks—includes limitations and benefits around range, speed, and security, and must be integrated to deliver the highest-performance smart grid. 

Wi-Fi
Wi-Fi is best suited for local area networks (LANs) and is reliable over short ranges. It is limited at longer ranges and susceptible to interference at high user population densities. Wi-Fi is best used for in-vehicle communication and interfacing with an EV's immediate surroundings.

DSRC
With the lowest latency of the three protocols, DSRC is best for high-security, high-speed, direct communication between vehicles and infrastructure. Its low latency is ideal for advanced driver assistance systems (ADAS), which require higher signal-response sensitivity for enhanced safety. DSRC works well for intermediate distance use cases up to 1km, such as vehicle-to-vehicle and vehicle-to-infrastructure communication to avoid collisions and navigate traffic stops.

C-V2X Networks
Given its extensive coverage area, cellular is best for remote functions and diagnostics. It provides high data throughput, making it the ideal protocol for vehicle-to-pedestrian communication. With a higher latency than DSRC, C-V2X networks are better for applications that do not need the fastest responsiveness, such as infotainment and over-the-air updates. 

Advanced Sensors for Real-Time Data Management

Many sensor technologies developed for autonomous vehicles (AVs) can apply to V2G. Engineers must employ sensors to monitor battery health through the battery management system (BMS), state of charge, and many parameters communicated over wireless protocols. In addition, smart power metering sensors feed the control algorithms data to direct how and when AVs use power. This enhancement results in optimized system performance and efficiency, which could also benefit V2G systems.

Implementation of V2G

While the technology for V2G is being developed, rolling it out at scale for national adoption is an entirely different problem. Several challenges remain for a national V2G network, but the opportunity for sustainability gains and grid resilience is enticing for both the public and private sectors.

Challenges and Opportunities

V2G technology presents complex challenges and opportunities, from battery degradation and supply chain impacts to market and regulatory barriers, all pivotal in shaping its widespread implementation and potential benefits.

Battery Degradation and Supply Chain Impact 
Research is ongoing to determine whether V2G technology strains the battery, reducing its lifecycle.[3]  Increasing the number of back-and-forth charging cycles could increase cycling strain and material fatigue. If not managed adequately, EV battery charging and discharging cycles can decrease capacity and life, which could lead to higher repair costs for an expensive component. However, smart charging algorithms can mitigate that effect and extend battery life. 

While smart charging and AI can mitigate strain losses, Li-ion battery chemistry is known to be less stable than some alternative battery chemistries. For example, lithium iron phosphate, used by Rivian and other EV manufacturers, does not degrade as much as Li-ion during repeated charge cycles.

Technical, Market, and Regulatory Barriers
Incorporating V2G technology into the current grid framework poses a range of difficulties. As the grid was built for one-way energy flow, technical complications include integrating bidirectional power flow, incorporating energy from renewable sources, and improving communication and control.

While addressing these technical barriers, the market will need to invest in capital for the enhanced infrastructure at the home and grid levels. During periods of economic uncertainty, leaders often prioritize short-term cost savings over long-term benefits, creating the need for new rules and standards to facilitate the widespread adoption of V2G systems.

Levelized energy storage cost ranges from $0.085/kWh to $0.243/kWh, with current net present value (NPV) estimates between −$1,317 and +$3,013. [4]  Battery chemistry improvement could drive V2G NPV to +$7,000 once the chemistries are mature. These figures underscore that widespread V2G can be massively profitable but will take investment to realize it.

Implementing V2G technology will also require regulations for interconnecting grids, electricity pricing relief, and subsidies to reduce the capital burden on public agencies and consumers. For example, the relatively recent ISO 15118-20 standard defines V2G communication interfaces for bidirectional charging between EVs and charging stations. [5]

Public and Private Sector Collaboration

To harness V2G's potential and move from demonstration projects to scaled adoption, regulators will need to create a supportive, performance-based environment to drive the behaviors the market needs. Local utilities and governments must enable widespread charging infrastructure and support technology implementation in vehicles and the grid.

Educating the public about V2G's benefits to individuals and promoting the use of EVs are also essential tasks. Increasing consumer awareness will increase adoption and improve chances for V2G technology to succeed. In doing so, the energy industry will take a significant step toward enhancing sustainability, increasing access to and adoption of renewable energy, and helping power resiliency, thus contributing to developing a sustainable energy future.

Conclusion 

V2G technology is revolutionizing energy utilization. It can leverage expanding global EV adoption to mobilize power to augment the grid. It enables widespread collection, storage, and use of intermittent renewable energy sources like wind and solar to decarbonize energy further while reducing consumer costs.

Collaboration between the public and private sectors will be needed to develop enhanced battery chemistry, infrastructure, and component enhancements to adopt bidirectional power technology. Finally, regulations and a standardized landscape will be written, and the rules of engagement for existing and new market participants will be established to achieve a national bidirectional energy landscape.

[1] https://www.marketsandmarkets.com/Market-Reports/smart-grid-market-208777577.html