Electric School Buses and the Grid - Unlocking the power of school transportation to build resilience and a clean energy future - PennEnvironment
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Electric School Buses
and the Grid
Unlocking the power of school transportation
to build resilience and a clean energy future
JAMES HORROX AND SARAH NICK, FRONTIER GROUP
MATTHEW CASALE, U.S. PIRG EDUCATION FUND
SPRING 2022
Acknowledgments
The authors wish to thank Greggory Kresge, Eleanor Jackson, Katrina McLaughlin, Carla
Walker, Michelle Levinson, Justin Balik, Sue Gander, Brittany Barrett, Stephanie Ly and Jennifer
Rennicks of the World Resources Institute for their review of drafts of this document, as well as
their insights and suggestions. The authors also thank Sean Leach, Manager, Training & Fleet
Operations, Highland Electric; Travis Madsen, Transportation Program Director, Southwest
Energy Efficiency Project; Matt Lehrman, Energy Strategy Coordinator, City of Boulder; and
Peter Smith, Consultant, European Structural Investment Funds and Regional Development
(UK). Thanks also to Susan Rakov, Tony Dutzik and Bryn Huxley-Reicher of Frontier Group for
editorial support.
PennPIRG Education Fund and PennEnvironment Research & Policy Center thank the
World Resources Institute for making this report possible. The authors bear responsibility
for any factual errors. Policy recommendations are those of PennPIRG Education Fund and
PennEnvironment Research & Policy Center. The views expressed in this report are those of the
authors and do not necessarily reflect the views of our funders or those who provided review.
2022 PennPIRG Education Fund. Some Rights Reserved. This work is licensed under a
Creative Commons Attribution Non-Commercial No Derivatives 3.0 Unported License. To view
the terms of this license, visit creativecommons.org/licenses/by-nc-nd/3.0.
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Cover photo courtesy of Lion Electric
Contents
EXECUTIVE SUMMARY........................................................................................................................4
INTRODUCTION..................................................................................................................................10
WHY ELECTRIC SCHOOL BUSES AND VEHICLE-TO-GRID TECHNOLOGIES?............................... 12
Energy storage is a critical piece of America’s future electric grid...................................................................12
Energy storage supports the transition to clean energy.............................................................................12
Energy storage enhances community resilience.........................................................................................12
Vehicle-to-grid technology – what it is and how it works..................................................................................14
School buses are a promising application of V2G..............................................................................................15
ELECTRIC SCHOOL BUSES AND V2G DELIVER VALUABLE BENEFITS......................................... 16
Environmental benefits..........................................................................................................................................17
Benefits for the grid...............................................................................................................................................18
Benefits to communities.......................................................................................................................................20
Electric school buses and V2G can make financial sense for school districts................................................21
ELECTRIC SCHOOL BUSES AND V2G TECHNOLOGIES TODAY.....................................................23
Electric school buses on the rise..........................................................................................................................23
Electric school buses and V2G technology.........................................................................................................24
Electric school buses could be a major energy storage resource....................................................................25
V2G IN ACTION...................................................................................................................................27
CHALLENGES LIMITING THE ADOPTION OF ELECTRIC SCHOOL BUSES....................................28
POLICY RECOMMENDATIONS...........................................................................................................31
Recommendations for the federal government..................................................................................................31
Recommendations for states................................................................................................................................32
Recommendations for regulators and utilities....................................................................................................32
Recommendations for school districts................................................................................................................33
METHODOLOGY..................................................................................................................................34
APPENDIX 1: SCHOOL BUS FLEET POTENTIAL STORAGE CAPACITY BY STATE.......................36
NOTES ................................................................................................................................................38
Executive summary
SCHOOL BUSES are the largest form of pub- tors should work to unlock these benefits
lic transportation in the United States. Ev- through creative public policies and part-
ery day, 480,000 of them carry up to half of nerships.
America’s children to school and back.1
The unique characteristics of school buses
Currently, fewer than 1% of the nation’s school make them ideally suited to serve as a source
buses are powered by electricity, but with of energy storage and emergency power.
advances in electric bus technology, growing Their use patterns allow them to be available
understanding of the benefits of electrifica- as a source of large volumes of energy stor-
tion, and now a fresh influx of federal money age, especially at the times when the grid is
through the Infrastructure Investment and most vulnerable.4 If every yellow school bus
Jobs Act, electric school buses are becom- currently in operation across the United
ing an increasingly viable option for school States were replaced with a V2G-capable
districts.2 Electric school bus models are now electric bus of the same type, this would
available to meet every use case, and the num- add over 60 gigawatt-hours (GWh) to the
ber of districts that have committed to electric country’s capacity to store electricity.
school bus adoption, or have drawn up plans
to do so, is growing. V2G technology can deliver benefits for
vehicle owners, utility ratepayers and com-
Transitioning to electric school buses would munities.
provide numerous benefits to communities
and the environment, including improving Electric school buses with V2G technol-
children’s health and reducing air and noise ogy can reduce greenhouse gas emissions
pollution, as well as reducing the dispropor- from both the transportation and power
tionate burden that this pollution places on generation sectors – the two sectors of the
underserved communities.3 U.S. economy that contribute most to global
warming.5
Electric school buses have the potential
to bring even greater benefits if they are • Replacing all of the country’s diesel-
equipped with technology that allows powered school buses with electric
them to deliver power to buildings and models would in itself contribute to
back to the grid. a sizable reduction in greenhouse
emissions, avoiding roughly 8 million
Vehicle-to-grid (V2G) technology enables metric tons of emissions per year.6
electric school buses to provide stability,
capacity and emergency power to the grid • A 2016 study found that the use of V2G in
when needed, and potentially to earn rev- electric school buses could eliminate an
enue for school districts for providing these average of more than 1,000 metric tons of
and other services. Policy-makers, utili- CO2-equivalent greenhouse gas emissions
ties, school districts and transport opera- over the lifetime of the bus.7 The same
PAGE 4
study found that the use of V2G elimi- “substantial” mitigation of “ramping”
nates enough pollution to completely (sudden and potentially disruptive chang-
offset the air pollution damage caused by es in power production – a particular
charging electric school buses from the issue with solar) equivalent to avoiding
grid.8 construction of 35 600-MW natural gas
plants for that purpose.13
• A Columbia University study calculated
that a fleet of 1,550 electric school buses Energy stored in school bus batteries can
providing peak shaving services – manag- also support a range of services to improve
ing overall energy demand to eliminate the functioning of the grid. These include:
short-term consumption spikes – could
reduce CO2 emissions by 5,500 tons over • Demand response/peak shaving: V2G
five years and produce a decrease in allows a vehicle to discharge energy back
electricity-related local air pollution.9 to the grid as demand peaks, lessening
the need for utilities to invest in or buy
• By enabling utilities to draw on distribut- power from dirty and expensive “peaker”
ed sources of energy, large-scale adoption power plants that run on fossil fuels.
of V2G technology could potentially
also lessen the need for new physical o A 2020 study found that a mix of V2G
power plants, bringing savings for utili- and G2V (grid-to-vehicle) can reduce
ties as well as environmental and health the difference between minimum
benefits – particularly for minority and and maximum daily net load enough
low-income areas, since peaker power to lessen utility companies’ need for
plants are often located in these areas.10 costly capacity expansion and help
maintain electricity price stability.14
The battery storage provided by elec-
tric buses could speed the transition to a • Energy arbitrage: By purchasing and
renewable energy grid, since batteries can storing energy when demand and cost are
absorb renewable energy when it is avail- low and redistributing it when demand is
able in abundance and release it during high, energy arbitrage could enable owners
periods when it isn’t, such as at night (in the of distributed storage provided by V2G EV
case of solar).11 fleets to bid on energy markets alongside
operators of peaker plants, thus providing
• A 2017 study calculated that if a signifi- storage owners with a source of revenue.15
cant share of the light-duty motor
vehicles currently registered in the terri- o A 2019 study assessing the economic
tory covered by the PJM Interconnection viability of inserting V2G systems into
– the largest power grid operator in the energy spot markets for the purpose
U.S. – were electric and V2G-capable, this of energy arbitrage found that, based
could increase renewable energy devel- on the markets in 2019 in Germany,
opment by 51 GW.12 Similar benefits are revenues could range from €200 to
anticipated with electric school buses. €1,300 ($235 to $1500) per EV per year.16
• A California study found that a mix of In addition to V2G capabilities, when
V1G (or ‘smart charging’ – unidirec- equipped with the right technology, electric
tional controlled charging where EVs school buses can bring further benefits, for
or chargers modify their charging rate example providing backup power to support
according to signals from the grid opera- emergency management efforts and criti-
tor) and V2G-equipped EVs can enable cal infrastructure during power outages.17
PAGE 5A fleet of V2G-enabled electric school buses put in place, including appropriate rates
could become an important temporary power and tariffs, V2G school buses can poten-
source during outages – essentially becoming tially benefit school districts by providing
a fleet of mobile batteries that can be deployed services to the grid for which school dis-
at short notice to provide emergency power to tricts may be compensated in various ways
homes, businesses, hospitals and shelters.18 by utilities and system operators.20
With the right incentives and effective col- • Modelling of a V2G peak shaving
laboration between school districts and program using a fleet of school buses in
utilities, electric school buses can be a cost- California found that the savings creat-
efficient alternative to their diesel counter- ed outweighed the costs the program
parts, producing major savings in lower incurred, making it beneficial for both
operating costs from reduced spending on utilities and schools.21
maintenance and fuel, while also provid-
ing greater predictability in costs due to the Replacing every yellow school bus cur-
relative stability of electricity prices com- rently in operation across the United States
pared to fossil fuel prices.19 with a V2G-capable electric bus of the same
type would create a total of 61.5 GWh of
When these vehicles are equipped with extra stored energy capacity – enough to
V2G, the financial benefits can be higher power more than 200,000 average Ameri-
still. Provided the right mechanisms are can homes for a week – and 6.28 gigawatts
Potential Energy Capacity
by State [MWh]
data not available
1 – 500
501 – 1,000
1,001 – 5,000
5,001+
Figure ES-1. Potential electricity storage capacity of school bus fleets by state if states’ existing fleets
were replaced with electric buses.
PAGE 6(GW) of instantaneous power, providing • Develop tools and educational materials
power output equivalent to over 1.2 million to enable school districts to better under-
typical residential solar roof installations stand the costs and benefits of electric
or 16 average coal power generators.22 buses and V2G and thus be able to include
V2G benefits in any calculations of return
Electric buses could also provide valuable
on investment of electric school buses.
backup power during emergencies:
• Provide funding for V2G pilot programs
• The energy stored in a single Type D bus
to enable a fuller understanding of the
could power the equivalent of five operat-
challenges of V2G and the costs and
ing rooms for more than eight hours, and
benefits it can bring to school districts,
a single operating room for 43 hours.23
utilities and other stakeholders, as well
• Electric school buses could also provide as to develop best practices to enable all
backup power in remote areas that need stakeholders to get the most out of this
electricity during outages. technology. Funding should be allocated
to a diversity of districts, including those
V2G technology is still in its infancy, and serving underserved populations.
while it potentially opens up a range of
opportunities for schools, utilities and com- • Support research to develop and
munities, there are still a number of barriers standardize hardware, software, regula-
that will need to be overcome before those tions and practices needed for electric
opportunities can be fully accessed. school buses to integrate with the grid and
participate in energy markets, as well as to
Realizing the full potential of V2G school determine the value of V2G and the poten-
buses will require collaboration between tial benefits it can produce.25
school districts, utilities, vendors and
other entities, and revising public poli- • Increase funding for research on poten-
cies to ensure that investments in electric tial business models for public-private
school buses and V2G make financial partnerships to help school districts
sense for school districts and utilities. with the upfront costs of electric school
bus adoption, including identification of
To help make this happen, the federal gov- federal, state and local policies that may
ernment should: create barriers or incentives to such models,
and develop resources to inform state and
• Invest in electric school buses. The Infra-
school district decision-making.
structure Investment and Jobs Act passed
in November 2021 allocates $2.5 billion States should:
for new electric school bus purchases and
a further $2.5 billion for alternative fuel • Develop policies to unlock the various
buses – including electric ones.24 Maximiz- value streams V2G can provide. Such
ing the benefits V2G school buses are policies might include exempting bus
able to deliver will require large numbers owners from regulation as public utilities
of buses, which will necessitate further, and experimenting with feed-in-tariff (FIT)
sustained federal investment over the programs and other forms of compensation
coming years, with funding particu- that may provide a simple, appealing way
larly targeted at under-resourced school of compensating school districts for the
districts. V2G services they provide.
PAGE 7• Provide grant/voucher programs and Regulators and utilities should:
subsidies for school districts to go
electric. This will ensure school districts • Clarify the regulatory status of V2G
and the communities they serve will operations and virtual power plants to
experience the cleaner air, reduced green- allow them access to energy markets.
house gas emissions and other benefits State public utility commissions should
of electric buses without additional develop a coherent regulatory framework
financial burdens.26 The process of apply- for V2G and ensure that electric vehicles
ing for funding should be streamlined with bidirectional flow are not subject to
to minimize administrative burdens on the same laws and regulations as public
school districts and ensure that school utilities.
districts do not have to cover upfront • Provide funding for V2G pilot
costs for application or the procurement programs. Utilities should provide finan-
of buses.27 cial assistance to enable school districts
• Prioritize funding for underserved to participate in V2G pilot programs. This
communities. Communities that suffer should include assistance covering the
the most from the environmental and upfront cost of buses, as well as charg-
public health impacts of diesel school ing infrastructure and technical and
buses are often those with the fewest operational support, and incentives for
resources available to invest in transi- early adoption, particularly to ensure that
tioning to electric ones. Under-resourced under-resourced districts have the oppor-
school districts, including majority-minor- tunity to participate in well-supported
ity schools and those serving low-income V2G pilot programs.
communities and communities facing • Encourage the creation of financing
disproportionate air pollution, should be programs whereby utilities front the
given priority in the allocation of funds initial investment for electric school
so as to ensure that those with the most buses and allow school districts to pay
to gain from clean transportation have back on utility bills as they save on fuel
the resources necessary to cover vehicle and maintenance costs. Such programs
purchases, infrastructure and operat- can help school districts overcome the
ing costs, and the provision of job train- higher upfront costs of electric buses and
ing programs to address the concerns of deliver monetary savings immediately,
mechanics and maintenance staff. opening the door to participation for a
• Develop a roadmap to enable regulators wider variety of school districts, includ-
to support the development of V2G and ing districts with fewer resources.
facilitate the creation of regulations and • Restructure electricity rates so as to
policies to minimize the risks for utilities provide discounted off-peak charging,
and school districts. This would pave the limit or eliminate demand charges for
way for standardization and interoper- EV and electric school bus charging, and
ability of V2G infrastructure, encourage experiment with policies and practices
coordination between key stakeholders, that allow buses to be used for energy
and provide greater clarity on regulatory storage and employ vehicle-to-grid
and policy frameworks so as to give utili- technology. Such policies might include
ties the necessary support for getting V2G premium tariff rates for V2G power
initiatives approved and implemented.28
PAGE 8similar to current feed-in-tariff programs economies of scale in infrastructure, opera-
for renewable energy.29 tional experience, and electricity pricing.
• Work to establish dialogue and collab- • Invest in as large a fleet as possible as
orative partnerships with school districts soon as possible. Districts should also
and public officials in planning and ensure the availability of additional electri-
implementing a transition to electric bus cal capacity and build the infrastructure to
fleets which is beneficial to all parties be able to add more chargers. The larger the
involved, for example including the devel- fleet, the greater its ability to participate in
opment of rates for electricity specific to EV-specific programs.
electric school buses.
• Establish solid collaborative partnerships
School districts should: with utilities from an early stage and
open a dialogue about goals and interests
• Commit to a full transition to electric from the outset. School districts should
buses on a specific timeline. These work with public officials and local utilities
commitments will help grow the market, to enact a transportation rate for electric-
drive technological innovation, and enable ity and use rate modeling in the planning
school districts to reap the benefits of process for launching electric bus service.
PAGE 9Introduction
IN 1892, A SCHOOL DISTRICT in Ohio commis- came into being it was against the backdrop
sioned Indiana-based vehicle manufacturer of an auto industry on the rise and a growing
Wayne Works to build a wagon specifically cultural infatuation with, and reliance on, the
designed for student transportation. Horse- internal combustion engine – as well as a gen-
drawn buggies, known as “kid hacks,” were eral lack of understanding of the health and
already carrying children to and from school environmental impacts of fossil fuel-powered
in parts of the country, but with Wayne vehicles. The job those vehicles was designed
Works’ “School Car,” as it was known, a to do was simple: get children to school and
vehicle purpose-built for the task began to back, safely and efficiently.
take shape.30 In 1910, the company rebuilt the
School Car on the chassis of an automobile, A century later, electric school buses (ESBs)
strapped an engine to it and launched its first have proven themselves capable of doing that
motorized version of the vehicle. In the years same simple but critically important job, and
that followed, other auto manufacturers keen in a way that addresses the priorities and
to get in on the burgeoning school transporta- challenges of a 21st century transportation
tion sector began adapting the bodies of kid system. Because ESBs produce no tailpipe
hacks and school cars to truck frames, add- emissions, they don’t emit the air pollutants
ing new features like steel sides and glass or greenhouse gas emissions of their diesel
windows to create a vehicle akin to what we counterparts.32 Since the energy that powers
would now recognize as a school bus. In 1939, ESBs will increasingly come from renew-
the first national conference on school trans- able sources, greenhouse gas emissions from
portation decided on a color scheme, and an electricity generation are expected to continu-
American icon was born. ally reduce as well. Since ESBs rely on highly
efficient electric motors rather than the less
Today, 480,000 school buses carry more than efficient complex mechanics of the internal
25 million American children to school every combustion engine, they are cheaper and
day.31 But just as the motorized school car easier to maintain, bringing substantial sav-
replaced the kid hack in the early years of ings in maintenance and fuel costs.33
the 20th century, today, a new iteration of this
most quintessentially American of vehicles But there’s another thing that sets these
has arrived on the nation’s streets: the battery- vehicles apart from their predecessors.
powered, zero-emission electric school bus.
A conventional school bus has one main use:
The electric school bus, like the kid hack and it carries children to and from school. For the
the school car before it, is a creation of its rest of the day, and throughout school holi-
time. When the first motorized school cars days – aside from occasional field trips and
PAGE 10summer camps – it sits in a depot doing The potential environmental, health and
nothing. In other words, for the vast major- financial benefits of electric school buses
ity of the calendar year, a diesel school bus have already been established both in
delivers no return on investment for the theory and practice, and school districts
school district that operates it.34 Electric that have added them to their fleets have
buses, by contrast, have the potential to pro- often found that they provide a reliable
vide an array of value streams that can ben- and cost-effective alternative to their fossil
efit the school districts that own and operate fuel forebears. A growing body of recent
them, and the communities they serve. research and experience in on-the-ground
demonstration and pilot projects indicate
The key to unlocking these benefits lies in that V2G technology may be able to unlock
the fact that as well as drawing power from even more benefits. V2G, however, is still
the grid, electric vehicles can also deliver very much in its early days. There is much
power back to the grid. Equipping school yet to learn, and a great deal more to be
buses with vehicle-to-grid (V2G) technology done in the way of research and develop-
can bring in revenue for schools and can ment, as well as real-world deployment
pay dividends for the grid, providing sta- of this technology. Smart and bold policy
bility, extra capacity and emergency power action now can accelerate progress toward
when needed, as well as a range of other unlocking the full potential of electric
so-called “grid services” that will become school buses – and bring the next revolution
ever more critical as the nation transitions in school transportation a little bit closer.
to renewable energy.
PAGE 11Why electric school buses and
vehicle-to-grid technologies?
What is V2G, why is it important and why are school buses well-suited to support it?
ELECTRIC SCHOOL BUSES protect the health balance the supply of power with demand
and safety of children and cut the air pol- for electricity at every second of every day –
lution and carbon emissions produced by a task that becomes more complex when it’s
diesel-powered school buses. With vehicle- not just the demand for power that’s variable,
to-grid (V2G) technologies, the batteries but also its supply.37
of those buses can also be used to store
electricity to support the grid and, in their Energy storage – including in vehicle bat-
vehicle-to-building (V2B) applications, pro- teries – is a critical tool that allows utilities
vide backup power to buildings and critical to absorb and store renewable energy when
facilities during emergencies. it is available in large quantities and deliver
it during periods when the renewable
Energy storage is a critical piece of resources are not as abundant or available.
America’s future electric grid Energy storage can deliver other benefits
Since the U.S. electricity grid was built – to the grid as well. By injecting power into
much of it more than half a century ago the grid at the times of greatest demand,
– the way we produce, distribute and use energy storage can also reduce the need to
energy has changed dramatically, with new tap more expensive generation sources –
developments bringing new challenges and often powered by fossil fuels – to meet peak
placing new strains on the grid.35 demand.38 Expanding the availability of
small-scale battery storage in our communi-
ENERGY STORAGE SUPPORTS THE ties can reduce the need for new stationary
TRANSITION TO CLEAN ENERGY grid storage that brings substantial financial
The last decade has seen dramatic growth in costs for utility companies.39
clean energy that is good for consumers and
necessary for the nation’s efforts to fight cli- ENERGY STORAGE ENHANCES
mate change.36 Wind and solar power, how- COMMUNITY RESILIENCE
ever, differ from the big, centralized power Energy storage can also help to make the
plants for which America’s existing power grid and our communities more resilient,
grid was built. Solar and wind power genera- enabling the grid to absorb shocks so as to
tors only produce power intermittently, and prevent disruptions, manage disruptions as
not always at times that coincide with peri- they unfold, and return quickly to normal
ods of highest demand (solar panels don’t operation, thus mitigating the scale, length
generate electricity at night, for example). In and impact of power outages on commu-
order to maintain the proper functioning of nities.40 Many of the same events that have
the grid, utilities and grid operators have to highlighted the importance of grid resil-
PAGE 12ience over recent years have also underlined its backup generator failed, and during Hur-
the need for back-up power storage. Extreme ricane Sandy, the generators at a number of
weather events such as Hurricane Katrina, hospitals on the East Coast failed to function
Hurricane Ida, Hurricane Sandy, Hurri- properly, including at New York University
cane Sally and the Texas cold snap of 2021 Langone Medical Center, which was forced
have exposed the vulnerabilities of cur- to evacuate all of its patients after both of its
rent emergency power systems to provide backup power systems failed.46
backup power in cases of large-scale grid
disruption, the consequences of which can Recent natural disasters have shown the
be particularly serious for hospitals, nursing particular importance of grid resiliency and
homes and other healthcare facilities. the availability of backup power for the most
vulnerable communities, including low-
The current emergency power supply systems income and minority populations.47 Statistics
that provide standby power to these kinds show that Black and Hispanic communities
of facilities are known to be susceptible to experience more frequent power outages in
design, capacity and maintenance issues, and general than white Americans, and during
few facilities are able to keep all of their sys- natural disasters these disparities are magni-
tems running using power from emergency fied.48 Historically underserved communities
standby generators alone.41 In addition, many often wait longer than more affluent neigh-
facilities have insufficient generator capacity borhoods for power to be restored, as was
to provide for their usual power demand in the case, for example, in Puerto Rico, when
full in the event that one generator fails or is Hurricane Maria knocked out key electricity
otherwise out of action – and not all have a transmission and distribution lines leaving
backup energy source at all, and in emergency the Puerto Rican archipelago without power.49
situations, the absence of reliable backup Similarly, when rolling blackouts during the
power means they often have to scale back February 2021 cold snap left millions of Texas
their operations or close altogether.42 Often residents without power, marginalized com-
these vulnerabilities have a disproportionate munities were the first to be hit with power
impact on the very people most likely to be outages and expected to have the longest wait
in need of such services. A recent survey of to be reconnected.50 In Austin, for example,
community health centers in California found the decision to prioritize keeping power on
that only 44% of such facilities had backup in downtown areas benefited residents of
generators, and even in those that did, these the more affluent neighborhoods nearby,
generators were unable to provide sufficient while hundreds of thousands of homes in
power to operate all their systems.43 Seven predominantly Black and Hispanic neighbor-
million Californians, many of them in rural hoods elsewhere were left without electricity.51
and low-income urban areas, are dependent
on nonprofit community health centers for The fact that emergency backup generators are
their primary health care.44 often powered by diesel, gasoline or propane
brings its own problems – not least of which
The consequences of these shortcomings being that these energy sources may them-
can be severe. After Hurricane Katrina, for selves be inaccessible in an emergency situa-
example, power outages and inadequate tion, either due to fuel scarcity or the inability
emergency backup power led to the deaths of some gas stations to run their pumps
of a number of patients at Memorial Medi- during power outages. Moreover, reliance on
cal Center in New Orleans.45 During Hurri- these generators during power shutdowns
cane Irene, Johnson Memorial Medical Center leads to increased air pollution and other
in Stafford, CT, had to be evacuated when risks to households that use them.52 Since 2017,
PAGE 13at least 39 Americans have died from carbon give EV owners the ability to access energy
monoxide poisoning after storms.53 Of the 28 markets, thus enabling the vehicle to carry
people who died in the aftermath of Hurricane out “grid services,” among other benefits.
Laura, which knocked out the electrical grid V2G systems can also use software to pull
in southwest Louisiana, leaving communities together the combined power of large num-
without power for weeks, 14 died as a result of bers of vehicles to create a “virtual power
carbon monoxide poisoning from emergency plant” (VPP): a decentralized network of
generators.54 flexible power generation and storage.57
These VPPs take the excess stored energy
Vehicle-to-grid technology – from each individual EV and treat it as a
what it is and how it works single energy resource, enabling this virtu-
ally aggregated set of resources to perform
Vehicle-to-grid technologies – abbreviated
ancillary services to the grid and also sell
as “V2G” – allow the batteries of electric cars
energy back to utility companies.58
and buses to be used as small-scale forms of
energy storage to support the functioning of To do this, V2G systems require three main
the grid. physical elements: 1) electric vehicles fit-
There are various ways that electric vehicles ted with battery-management software
interact with the grid: and hardware that allows the bidirectional
flow of power; 2) electric vehicle supply
• Most electric vehicle owners currently equipment (EVSE) – i.e., charging sta-
charge their vehicle through one-way charg- tions – which, coupled with the necessary
ing: plugging it into a charging station and infrastructure to enable bidirectional flow,
drawing electricity from the grid. deliver electrons to and from the grid; and
3) communication technologies mediat-
• V1G “smart charging,” a variant of
ing between vehicles and grid operators
one-way charging, enables charging to be
who control the charging and discharging
scheduled for times when grid demand
of the vehicle’s battery.59 These mediating
is anticipated to be low, and/or adjust
technologies sense the status of the grid,
charging according to signals from the
and also receive signals from the grid (for
grid operator so as to optimize energy
example, at times of critical peak demand)
consumption and best serve the needs of
to enable a vehicle battery to be charged
both the grid and the vehicle at a given
and discharged to best serve the needs of
time, based on factors such as overall
the grid at a given time. They also track the
electricity demand and how much energy
services provided so that the vehicle own-
the vehicle needs.55
ers can receive compensation for the use of
• Bidirectional charging allows electricity to their vehicles.60
flow both ways, enabling an EV owner to
One example of this software is the GIVe
use excess energy stored in an EV battery for
(Grid Integrated Vehicle) platform devel-
other purposes, including in homes (V2H),
oped by San Diego-based company Nuvve.61
in buildings in general (V2B), or, in the case
The platform enables bidirectional V2G
of vehicle-to-grid (V2G) systems, returning
charging and grid-connected load man-
electricity to the grid itself.56
agement services when connected to a
V2G is essentially an advanced form of V2G-compatible vehicle via a specific type
bidirectional charging which, in areas that of charger, enabling EV batteries to store
have energy markets and/or are controlled and discharge energy when needed and
by Independent System Operators (ISOs), can vehicle owners to sell stored energy back
PAGE 14to energy markets.62 These chargers enable locations, school bus fleets not only bring the
the automated charging and discharging benefit of large numbers of vehicles being
of a vehicle’s battery according to instruc- available simultaneously, but they also oper-
tions received from a cloud-based app ate on a predictable and limited schedule.
that ensures that all vehicles on the plat- This means that the vehicles are available to
form have sufficient charge for their next be charged during the day or at night, and
trip before ascertaining how much of the discharged during peak demand hours such
stored energy in the battery is available to as early evening, when demand is highest
sell back to the grid.63 When multiple EVs but renewable energy from certain sources,
are plugged into the same system at the such as solar, is not being produced.68 On the
same time, the platform can create a virtual other hand, predictable schedules also allow
power plant from their batteries.64 operators more choice over when the vehicles
are charged and discharged, meaning that an
School buses are a promising entire fleet need not be discharged simultane-
application of V2G ously but rather at times best suited to serving
In theory, any electric vehicle, provided the needs of the grid.
it has the right hardware and software,
The second feature of school buses that makes
could be capable of sending power back to
them ideal candidates for V2G is their large
the grid. However, there are a number of
battery sizes. Battery capacity in personal
characteristics unique to school buses – as
(light-duty) EVs is rarely higher than around
opposed to other electric vehicles, even
100 kWh, potentially leaving little excess capac-
including transit buses – that make them
ity to provide energy back to the grid.69 While
particularly well-suited to V2G applications.
battery size should be matched to a vehicle’s
Unlike transit buses, which spend most of duty cycle – no bus operator should oversize
their time in use, school buses operate for their vehicles’ batteries beyond the needs of
an average of only four to five hours per day their fleet – electric school buses by nature
and are mostly idle during weekends and have greater power needs and larger battery
school holidays – which together amount to capacity than light-duty vehicles.70 Larger
around half of the calendar year.65 In other capacities mean more electricity storage. In
words, for roughly 20 hours a day during addition, while battery degradation is often a
the school year, and often 24 hours a day on concern with V2G due to the increased num-
weekends and holidays, many buses – and ber of charges and discharges V2G entails, the
their batteries – are sitting idle.66 percentage of loss should be less significant
with the larger school bus batteries than with
These use patterns not only enable school smaller vehicles that have smaller batteries.71
buses to potentially be available as a source
of large volumes of energy storage to sup- With large numbers of large vehicle batter-
port the grid, but also to do so at the times ies available simultaneously at regular, pre-
when the grid is at its most vulnerable. Such scheduled times, electric school buses would
periods include the “shoulder” period in the seem uniquely positioned to act as a virtual
early evening when electricity demand is power plant. Aggregating the vehicles’ batter-
high but solar panels are no longer produc- ies across an entire fleet, district or region in
ing electricity, as well as over summer and theory enables them to collectively perform a
winter breaks, when peak demand is often number of functions, including providing grid
at its highest with more families at home and stabilization services and facilitating the inte-
using air conditioning or heating.67 Whereas gration of renewable energy into the energy
most EVs charge at unpredictable times and markets (see p. 17).72
PAGE 15Electric school buses and V2G
deliver valuable benefits
ROUGHLY 95% of U.S. school buses run on health and environmental benefits, since
diesel – which produces dangerous pollut- ESBs rely on highly efficient electric motors,
ants with proven links to numerous health they are cheaper to fuel and easier to
impacts, including cancer, asthma and maintain than internal combustion engine
autism.73 Research suggests that air pollu- vehicles, thus creating substantial savings in
tion inside school buses can be significantly lifetime costs of operation.79
higher than concentrations typically found
outdoors.74 By one analysis, concentra- Electric school buses can deliver environ-
tions of particulate matter in school buses mental, health and financial benefits – even
are more than double those of roadway if they never supply electricity to the grid.
concentrations and four times those of But a growing body of recent research indi-
average outdoor levels.75 Moreover, the cates that V2G-enabled ESBs may be able to
harmful emissions from diesel school buses bring additional benefits.
disproportionately affect students from
Photo: Theurv via Wikimedia, CC BY 4.0
low-income communities. Sixty percent of
students from low-income backgrounds
travel to school by bus, compared to 45%
of students from more affluent families.76
Minority ethnic and racial groups are more
likely to bear the brunt of air pollution from
road traffic pollution in general, since the
historical legacy of discriminatory housing
and zoning policies means that these com-
munities tend to be located in closer prox-
imity to highways.77
Since ESBs produce no tailpipe emissions,
they don’t emit the air pollutants or green-
house gases of diesel buses, and they are
likely to become cleaner over time, as more
of the electricity used to power them comes
from renewable sources. By one estimate,
replacing all U.S. diesel-powered school
buses with electric models could avoid The first all-electric school bus in California, outside
roughly 8 million metric tons (MMT) of the California capitol building in Sacramento in 2014.
emissions per year.78 In addition to their
PAGE 16Environmental benefits improving the health and wellbeing of
low-income and minority communities,
Although studies of electric school buses since current peaker power plants are often
specifically are scant, research has indicated located in these communities and have
that V2G technology can potentially play a negative health impacts.85
significant role in reducing greenhouse gas
emissions from both the transportation and V2G systems using the battery storage
power generation sectors – the two sectors provided by EVs are also one way in which
of the U.S. economy that contribute most to EVs could potentially play a key role in
the nation’s climate emissions.80 facilitating the large-scale integration of
renewable energy sources like solar and
• A study published in the journal Energies wind power. V2G-equipped vehicles are
in 2016 found that an electric school bus able to absorb renewable energy when it is
using V2G can potentially eliminate more available in abundance and release it during
than 1,000 metric tons of CO2-equiva- periods when it isn’t, such as in the evening,
lent emissions over the lifetime of the when large numbers of vehicles are not in
bus – roughly equivalent to the lifetime use, essentially making them energy stor-
emissions of 19 passenger cars.81 The age units and thus mitigating challenges of
same study found that the use of V2G can keeping the grid in balance while relying
also eliminate air pollution from fossil- increasingly on renewable energy.86 Net-
fuel power plants working over typical worked battery storage in the form of large
capacity when accommodating high numbers of EVs aggregated in a VPP could
electricity demand fluctuations, with each enable electricity generators to scale back
bus providing enough energy back to the their contribution to meeting demand and
grid to reduce the mean cost of air pollu- draw from the network of battery storage
tion by $18,300 over the course of the and generation for the rest, thus lessening
vehicle’s lifetime.82 the need for costly capacity expansion of
• A recent study by Columbia University generation and transmission capacity and
concluded that electric school buses using helping to maintain electricity price stability
V2G have the potential to mitigate energy while at the same time easing the process of
production from natural gas “peaking” decarbonizing the nation’s electricity grid.87
power plants. The model calculated that a The ability of EVs to facilitate the integra-
fleet of 1,550 electric school buses provid- tion of renewable energy sources including
ing peak shaving services – managing wind and solar into the existing power grid
overall energy demand to eliminate short- has been the subject of a growing body of
term consumption spikes – could reduce research.
CO2 emissions by 5,500 tons over five
years and produce a significant decrease • A 2017 study found that if a substantial
in electricity-related local air pollution.83 scare of the light-duty motor vehicles
By enabling utilities to tap distributed currently registered in the territory
sources of energy — i.e., a virtual power covered by the PJM Interconnection – the
plant composed of vehicles owned by third largest power grid operator in the U.S. –
parties – V2G technology taken to scale were electric and V2G-capable, this could
could also lessen the need for new physical increase renewable energy development
power plants.84 In addition to the environ- by 51 GW within the PJM Interconnec-
mental benefits, this could ultimately create tion – an increase of 30% over scenarios
financial savings for utilities, as well as without V2G.88
PAGE 17• A California study found that a mix of ing a specific geographical area, such as a
V1G and V2G-equipped EVs can enable college campus or hospital, with energy
“substantial” mitigation of “ramping” produced by distributed sources – could
(sudden and potentially disrup- reduce operational costs, decrease reliance
tive changes in power production – a on the main grid and increase the share of
particular issue with solar) equivalent power from renewables.95
to avoiding construction of 35 600-MW
natural gas plants for that purpose.89 The Benefits for the grid
study highlighted a “substantial syner- Energy stored in the batteries of electric
gistic opportunity” if the target of 1.5 school buses can support a range of services
million ZEVs on California’s roads by and functions necessary for the grid to
2025 set in the state’s 2012 Zero-Emission function properly. These include:
Vehicle mandate were deployed to
provide power storage to support renew- • Demand response/peak shaving: Over
ables integration.90 the past two decades, the ratio of annual
peak-hour electricity demand to average
o The same study concluded that using hourly demand across the U.S. has risen
EVs instead of stationary storage significantly, meaning that utilities are
could save billions of dollars in having to serve an ever-increasing range
capital investments needed to enable of demand.96 Electric vehicles have a
a successful transition to renewable valuable part to play in minimizing peak
energy, and could be used as an incen- demand on the grid, which can be expen-
tive to accelerate the adoption of EVs.91 sive and environmentally damaging to
serve. Whereas one-way charging pulls
• Research in Latvia found that
electricity from the grid at a constant rate
V2G-capable EVs could play a substantial
until the battery is at maximum capac-
role in the integration and use of wind
ity, bidirectional charging allows a fully
power.92 The V2G system could provide
charged vehicle to store energy and
important “peak shaving” services and
discharge it back to a building to reduce
reduce CO2 emissions by around 100
that building’s demand for power from the
kilograms of CO2 per EV.93
grid, or, with the necessary infrastructure
• A 2016 study of the Canary Islands found in place, to supply power to the grid itself.
that V2G in conjunction with pumped
Demand response also has a role to play
hydro storage reduced dependence on
in mitigating challenges that arise from
fossil fuels while also increasing the
renewable energy generation – including
share of renewably-generated electric-
the fact that electricity generation from
ity and reducing carbon emissions. The
renewables does not necessarily coincide
study calculated that a fleet of 3,361 EVs
with times of highest demand. A 2020 Los
could potentially increase the share
Angeles case study evaluating changes
of renewable energy from the current
in net load in the Los Angeles power grid
(2015) level of 11% to 49%, leading to a
in a system with solar energy combined
26% reduction in electric power system
with projected numbers of EVs that would
CO2 emissions.94
be used for distributed storage found that
In addition, a number of studies have found a mix of V2G and grid-to-vehicle (G2V)
that introducing V2G to microgrids – local- technologies can effectively flatten out the
ized, self-sufficient grids able to operate so-called “duck curve” – the dip in energy
autonomously from the main grid, power- demand caused by solar generation during
PAGE 18WHAT IS THE “DUCK CURVE” AND WHY DOES IT MATTER?
Figure 1. The “duck curve” in California over a typical 24-hour period in the springtime.
Source: U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy.101
The so-called “duck curve” is the net elec- This poses a problem for utilities
tric system load (energy demand minus because it means they will increasingly
the supply of distributed renewable be forced to ramp up their dispatchable
energy) over the course of a given day.102 power plants to meet demand during
a morning peak (the duck’s tail), scale
As more solar comes online, the demand back or shut them down altogether
for electricity from traditional power during the day when solar generation
plants during daylight hours, when is highest (the duck’s belly), and then
solar is plentiful, drops. But peak energy quickly bring them all back online after
demand often occurs in the morning sunset (the duck’s head).
and early evening when solar is not
plentiful. During these periods – in the This costly process can be mitigated by
morning and evening – the electric grid using battery storage to absorb renew-
must meet that increased demand from able energy during the day when it
sources other than solar. So, as the nation is being generated in abundance and
transitions to renewable energy and the release it during peak periods when
portion of our energy that comes from it is not, thus lessening the need for
distributed solar resources during the utility companies to ramp up their
daytime increases, the dip in the middle generators during these hours to meet
of the curve gets lower, and the ramp up the increased demand – in other words,
to the evening peak gets steeper. “flattening” the duck curve.
PAGE 19the day and the steep increase that follows the purpose of energy arbitrage calcu-
after sunset – concluding that a smart grid lated that, based on the markets in 2019
V2G and G2V system can reduce the differ- in Germany, revenues could range from
ence between minimum and maximum €200 to €1,300 ($235 to $1,500) per EV
daily net load from 1.9 GW to just 500 per year, varying by geographic location
kW and reduce peak load by around 800 as well as available energy markets and
MW, from 3,500 MW to 2,700 MW.97 This production structure.104
is a significant reduction, the study notes,
which can lessen utility companies’ need • Grid resilience and emergency prepared-
for costly capacity expansion and help ness and response: For the electrical grid
maintain electricity price stability.98 The to be resilient, it needs to be able to antici-
study concludes that even a “moderate” EV pate, absorb, adapt to and quickly recover
adoption plan (assuming 127,000 EVs on from disruptions.105 V2G could provide
the road in the LA area) could give utili- grid operators with an on-demand source
ties enough battery storage capacity to help of power that would, among other uses,
“significantly” with peak load shifting and enable electric vehicles to provide backup
flattening the duck curve.99 power and mobile power supplies in
emergencies. A 2018 study by the U.S.
Another study from California concluded Department of Energy Electricity Adviso-
that the peak-shaving services a V2G- ry Committee found that backup power
enbled school bus fleet can provide can storage is one of the key ways V2G is
improve grid resiliency, in particular suited to enhancing grid resilience.106
during the summer months when peak
conditions can put a strain on electricity Benefits to communities
infrastructure. By alleviating the pressure Replacing diesel-powered school buses with
on this infrastructure, the study con- electric ones would provide numerous ben-
cluded, a V2G-equipped school bus fleet efits directly to the communities they serve,
can reduce both the risk of power out- including improving children’s health and
ages and the need for grid infrastructure reducing air and noise pollution, as well as
maintenance.100 reducing the disproportionate burden that
this pollution places on disadvantaged com-
• Energy arbitrage: Many utilities have munities.107 When equipped with V2G tech-
rate structures that charge users more for nology, these vehicles can bring a number of
power consumed during peak hours and further benefits to communities, including
less for “off peak” power. By purchas- playing a role in providing backup power to
ing and storing energy when demand support emergency management efforts and
and cost are low and redistributing it enhance the resilience of the electrical grid –
when demand is high, energy arbitrage something that will become ever more of a
enables owners of distributed energy, necessity over the coming years as extreme
such as VPPs – provided they are allowed weather events become more frequent
access to the electricity markets – to bid and more destructive as a result of climate
for energy demand alongside opera- change.108
tors of peaker plants, and thus provides
owners/operators of storage with a source A fleet of V2G-enabled electric school buses
of revenue.103 A 2019 study assessing could become important temporary power
the economic viability of inserting V2G sources during outages – essentially provid-
systems into energy spot markets for ing mobile batteries that can be deployed
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