Enbala Blog

ELECTRIC VEHICLES – good for our roads, good for our lungs, but good for our grids?

Posted by Lana Gonoratsky on Jun 20, 2018 11:26:00 AM

I take the bus to work. On any given weekday, you can find me waiting on the side of a road while vehicles of all shapes and sizes whiz by, leaving behind a trail of noise and exhaust. It would be all well and good if this was just another weekday annoyance that could be easily shrugged off, like a fresh pile of snow blocking the sidewalk or a texter blissfully skipping the line at a busy coffee shop. But that’s not the case. Vehicle exhaust is a known pollutant that significantly affects human health and the environment. Regulators put limits on emissions – but these generally focus on new car sales, and then they can still be tampered with. So as a commuter waiting at the side of a busy road, I don’t feel too reassured. But, when I see that clean technology goals for electric vehicles are on track, hear announcements from companies like Tesla, Thor and Volvo electrifying trucking fleets, and read about commitments by governments to support these efforts, I do feel hopeful.

canstockphoto16327050Clean Energy, EVs and the Grid

It’s not just our roads that are going to get cleaner. The Rocky Mountain Institute (RMI) estimates that approximately half of existing coal, nuclear and gas-fired power plants in the United States are likely to retire in the next 15 years and be replaced, in part, by renewable energy developments. 

This is great news for our lungs and ecosystems, but this could create a significant gap in demand. Renewable energy sources are intermittent. PVs work when the sun is shining, and turbines work when the wind is blowing. But our lifestyles, along with our electricity consumption, doesn’t necessarily coincide with the changing weather patterns. With the increase in EVs on our roads, there will be an increase of load on our grid. In particular, if we all charge our cars, buses and semis at the same time, then this mismatch of intermittent renewable resources and increase in peak electricity demand could lead to even higher risks of reduction in power output.

Peak Demand and Smart Charging 

Peak demand is a big deal. Before smart meters came around, 10% of a utility’s resources were always on, anticipating all of us ramping up our electricity use at the same time. This only happens a few times a year and just for a few hours, but not having that extra generation at the ready would result in significant blackouts and damage. So, charging all our EVs around the same time could potentially increase this peak demand occurrence from a few times a year to a few times a week!

However, with the introduction of smart meters, utilities have been able to implement demand response programs to incentivize their customers to reduce load during peak demand. With a new generation of communication and control technologies, utilities can go beyond demand response and enable “demand flexibility” by allowing major loads to continuously respond to peak demand forecasts, changing renewable supply levels and other applicable market signals. In fact, demand flexibility can unlock up to $13 billion per year of avoided grid investment, including investments associated with building new fossil fuel burning peaker plants to mitigate the increase in demand by EVs.

EV charging will cause an increase in overall electrical energy demand, but the greater challenge lies in where, when and how this charging takes place. Using demand flexibility – or in the case of EVs, “smart charging,” – can help turn these modes of transportation from a burden of peak demand into a significant grid resource, offering flexible capacity to the grid. On an aggregate basis, EVs could provide much needed flexibility to support growing levels of renewable generation by absorbing over-supply and by curtailing charging to mitigate peak demand.

Smart charging technology can potentially alleviate strain on the grid and turn EVs into an asset that can work for the benefit of the system. One method of doing this includes the EVSE (electric vehicle supply equipment) or EV charging station. In this case, the charger is integrated into a virtual power plant (VPP) platform that monitors, controls and optimizes its charging activity. When the VPP receives a signal of an imbalance of demand, it will dispatch the charger to pause charging.

Another method of smart charging involves the EV directly. Hardware is installed right into the onboard diagnostic port of the vehicle and can be controlled by customer-facing smart phone apps allowing the EV owner (or fleet operator) to enable constraints that ensure the vehicle is charged to a specified amount by the time they will need to use it. For example, an EV owner knows her EV battery will last longer when kept at a 20% - 60% state of charge (SOC), and she knows that her commute to and from the office consumes 10%. She will plug in her EV at her residence in the evening and use her smart phone to create constraints that (i) ensure her vehicle is charged to at least 30% (20% optimal SOC + 10% for the commute) by the time she needs to drive it in the morning and (ii) ensure charging is paused when the battery reaches 60% SOC. These constraints can then be pushed to the VPP, ensuring the EV owner’s needs are met while still optimizing charging to accommodate changes to demand on the grid.

V2G — Batteries on Wheels  

EVs use batteries that are typically associated with taking energy from the grid, converting power from AC to DC like the rechargeable batteries in cameras, smart phones and toothbrushes. But unlike those batteries, EV batteries can convert power from DC to AC, feeding it back into the grid. This ability, referred to as Vehicle-to-Grid (V2G), has been recognized as one of the EV revolution’s most promising prospects. 

Despite the introduction of Uber, car-sharing and fleet-management systems, vehicle utilization is low. It’s estimated that passenger vehicles are parked 95% of the time, making them a huge waste of space. But, if all these parked cars were electric and connected to the grid, utilities and power providers could use the EVs’ electric charge to balance itself. With the right amount of EVs sitting idle, waiting for their chance to take us from A to B, peak demand can be mitigated.

EVs are an ingenious form of storage that can be made to work for tiny grid imbalances as well as big ones. By turning stationary EVs into power providers using V2G and VPP technologies, utilities can ensure grid reliability while retiring old and inefficient power generators and preserving land and ecological conservation by avoiding construction of new power plants in remote areas.

Yes, EVs are Good for Our Grids

I for one am stoked for the transition to electric vehicles. To think that my daily dose of diesel exhaust will decrease over time makes me less surly about my commute. But as we improve our transportation and energy choices, we’ll need to develop new systems to work within. The current supply-follows-load model the grid has been using for over a century won’t work in this new landscape. We need to leverage opportunities to shift load to times of high renewable generation and use storage to handle peak demand. EVs let us do both. By connecting smart chargers, EVs and V2G technology into one platform that can monitor, control and optimize their use based on grid conditions and market signals, we can enable high utilization of renewable energy, expedite the uptake of clean, reliable transportation and secure a balanced grid.


Topics: virtual power plant, Electric vehicles, Distibuted energy resources, EVs

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