Locally Generated Reactive Power: A key component to widespread scaling of EV charging

02 Jul 2020

By Maggie Alexander

Growth in the electric vehicle (EV) industry is ramping quickly. This acceleration is driven by falling battery prices, regulatory changes, and the adoption of new technology. In California, the Public Utilities Commission (CPUC) energy division announced plans to put five million zero-emission vehicles (ZEV) on the road by 2030. Projects across the country involving adoption of EVs are moving from pilot stage to full fleet deployment – especially in the public transit industry. For example, growth in the global e-bus fleet was up 32 percent in 2018, according to a recent BloombergNEF report.

This upswell of EV adoption is encouraging in terms of achieving local and state-wide pollution-reduction and climate goals. Meeting EV charging demand, however – swapping gasoline for electricity – cannot be satisfied by the existing electric grid. 

The grid is unprepared to handle wide-spread electric fleet adoption because it lacks the infrastructure to do so.

For example, fully charging three standard electric buses requires the same amount of energy as it takes to power roughly190 homes, according to SEIA. Can you imagine building the necessary infrastructure to charge the equivalent of a housing subdivision every day, especially in the urban settings where bus fleet charging commonly occurs?  

Researchers at the University of Texas and the National Renewable Energy Laboratory have identified that, "if virtually all passenger cars in Texas were electrified today, that state would need approximately 110 more terawatt-hours of electricity per year—the average annual electricity consumption of 11 million homes. The added electricity demand would result in a 30 percent increase over current consumption in Texas." In California, this could mean nearly 50 percent more electricity than it currently consumes – an additional 120 terawatt-hours per year.

Producing enough energy to fulfill the growing demand for EV charging is a critical first step towards meeting transportation's shift to electrification, but delivering that energy is equally important - and more complicated. To deliver energy where and when it is needed requires all waveforms of energy (real, reactive power, and apparent power). 

Real, Reactive, and Apparent Power

In order to better understand these implications, we need to dig into the energy required to charge electric vehicles. The electricity that illuminates light bulbs and charges mobile phones is what is known as "real" or "active power", usually measured in Watts (W), kilowatts (kW), or megawatts (MW). However, moving real power across the grid and keeping machines operating consistently, efficiently, and economically requires "reactive power." Reactive power, measured in mega volt amps reactive (MVAr), enables real power to operate machines (including transmission wires), and holds real power in the correct voltage to allow it to do work, as well as helping to reduce the demand on the grid.

Both real and reactive power are commonly produced by large fossil fuel power plants, such as a spinning generator. Unlike real power, however, reactive power does not travel efficiently due to losses, so producing it at a distance and transmitting it to the load is expensive. Additionally, fluctuations in reactive power make the energy being transmitted on the grid unbalanced or unstable. Balancing reactive power requires voltage regulation, which injects or absorbs the correct voltage to bring reactive power into the proper power factor for transmission and use by a customer. An increase in generation to meet EV charging demand means that an increase in reactive power is also needed; when this generation occurs at a distant power plant, consumers end up footing the bill when utilities pass those costs on to ratepayers.

In addition to the expense of necessary reactive power generation and delivery, an added impediment to EV adoption is that the existing infrastructure for energy delivery (utility poles, wires, transformers, etc.) is not adequate for delivering the extra energy needed. BCG recently developed a model looking at the cost to utilities to upgrade the transmission and distribution system in order to meet electricity demand for transportation electrification. The model shows that a representative utility with 2-3 million customers will need to invest between $1,700 and $5,800 in grid upgrades per electric vehicle through 2030. Because these grid upgrades will primarily be covered in the rate base, the costs also will ultimately be passed on to their customers.  

Local Generation

One solution to combat the issues of inefficient, expensive reactive power generation (and costly infrastructure upgrades) is local generation. Instead of producing real and reactive power by fossil fuel generation at power plants located far from load, distributed energy resources (DERs) like rooftop solar can play a role in meeting demand for electricity closer to where it is needed. When aggregated, these DERs can also provide enough capacity to meet the entire fleet's charging needs. A grid with the capabilities to detect and operate DERs like spinning generators could incorporate and utilize locally produced real and reactive power, as it does now with fossil fuel sources. Harnessing local generation would impact the economics of EV charging, as well. By minimizing the transmission and delivery required, local power would mean fewer infrastructure upgrades and lower transmission costs. 

On their own, intermittent clean energy sources like solar and wind only generate real power, so reactive power is still supplied from the grid. But with energy management technology that can generate reactive as well as real power, locally and dynamically, energy generated from green resources can mimic a clean energy spinning generator—providing electricity for zero-emission charging. To do this in the most cost-effective manner, these solutions must produce the exact wave form of energy where it is needed the second it is needed so the grid does not need to supply it. This translates to more usable energy, and an average 30 percent reduction in energy costs.

For example, a Southern California-based transit authority has a fleet of 80 electric buses. Their local utility had imposed a new rate structure that froze demand charges for 5 years, but time-of-use (TOU) rates were extended with lowest peak periods in the middle of day. This makes it difficult for EV fleets to charge efficiently and economically, to avoid demand charges. By dynamically monitoring the bus fleet's energy needs and supplying energy from the optimal source (solar or storage) with energy management systems, specially designed software can provide a minimum savings of $6M in 10 years due to cost savings and system-wide efficiency.

For EV charging – whether a single light-duty car or a fleet of vehicles – the ability to dynamically generate and manage reactive power, and match the impedance of load with charging and discharging, can translate to 20-30 percent increased efficiency with battery system charging, and on discharging. This means more usable energy is produced to meet charging demand, and more money is saved, ensuring a faster return on investment than traditional EV charging infrastructure. These intelligent energy management solutions also allow for aggregated charging, opening up more vehicles to charge at the same time and optimizing energy costs for original equipment manufacturers (OEMs), such as electric bus manufacturers and fleet managers.

The adoption of electric vehicles is just beginning, but charging solutions that rely solely on the grid are too narrow of a solution to scale effectively. The BCG model predicts that rates could increase as much as 1.4 cents per kilowatt-hour (kWh), or 12 percent, as a result of the necessary grid upgrades needed to support the uptick in EV charging demand. Since most of the energy we use today, except for specific areas in the U.S., is still generated from fossil fuels, now is the time to re-envision an EV-friendly grid that can integrate more clean energy, reduce costs for consumers, and keep the grid stable. By better managing and utilizing clean energy and reactive power generation at its source, we can realize the full potential of zero-emission transportation and its benefits for the bottom line for consumers and utilities, as well as the air quality of the communities they serve.
 

Maggie Alexander, Director of Business Development at Apparent, is focused on establishing mutually beneficial partnerships and strategic ventures that enable everyone the ability to access the myriad of benefits from behind-the-meter distributed energy resources. She has more than a decade of experience in business and project development, establishing partnerships and projects with national and international governments, environmental organizations, electric utilities, and technology companies.

Apparent | http://www.apparent.com

 


Author: Maggie Alexander