Deep Decarbonization and Hydropower

Date01 April 2018
AuthorCharles R. Sensiba, Michael A. Swiger, and Sharon L. White
4-2018 NEWS & ANALYSIS 48 ELR 10309
and Hydropower
by Charles R. Sensiba, Michael A.
Swiger, and Sharon L. White
Charles R. Sensiba is a Partner with Troutman Sanders
LLP in Washington, D.C. Michael A. Swiger is a
Partner and Sharon L. White is Of Counsel with
Van Ness Feldman, LLP, in Washington, D.C.
Hydropower—both conventional and pumped stor-
age hydropower—is crucial to sustaining our transi-
tion to a decarbonized grid. Additional hydropower
development that meets modern environmental
requirements is essential to reduce the United States’
dependence on carbon. Realizing the full potential of
hydropower and maintaining the current hydropower
eet will likely depend on overcoming a number of
impediments, including lengthy and complex regu-
latory requirements, failure of electricity markets to
adequately compensate hydropower generators for the
grid benets they provide, environmental opposition
to new hydropower, and interest in dam removal. is
Article, excerpted from Michael B. Gerrard & John
C. Dernbach, eds., -
 (forthcoming in 2018 from
ELI Press), examines how these challenges can be
overcome with targeted legal and policy reforms.
I. Introduction
Hydropower, which generates electricity through fall-
ing water,1 is the nation’s most established and mature
renewable resource, and accounts for more than 6% of a ll
electricity generation and about one-half of all renewable
power in the United States.2 Hydropower resources serve
an essential role supporting the electric grid by provid-
ing low-cost, exible energy services, a nd a multitude of
secondary benets such as ood control, irrigation, water
supply, and recreational opportunities. Hydropower also is
critical in maintaining grid reliability and integrating vari-
able generation resources, such as solar and wind, that con-
tinue to come online in larger numbers. Because solar and
wind are intermittent resources, the electric grid cannot
rely on them in all hours; no other renewables but hydro-
power, and to a lesser degree geothermal and biomass, are
capable of quickly responding to the variable nature of
wind and solar, coming on- and o-line when needed to
ensure proper grid functioning.3
e Deep Decarbonization Pathways Project (DDPP)
report,       
States, recognizes the crucia l role of hydropower to sustain
our transition to a decarbonized electric grid—particularly
with rega rd to hydropower pumped storage4 and its abil-
ity to ba lance and integrate non-dispatchable renewables
and water power.5 In fact, the DDPP report assumes that
the installed capacity of pumped storage will need to more
than triple by 2050 to sustain a decarbonized grid.6
1. Hydropower also includes hydrokinetic technologies, which generate elec-
tricity from waves, currents, and tides within a water body.
2. See U.S. Energy Information Administration, Hydropower Explained, http:// (last updated June
13, 2017).
3. Combustion gas turbines also have this capability but are not renewable.
4. A pumped storage hydroelectric project can store and generate energy by
pumping water between an upper and lower reservoir at dierent eleva-
tions. During times of low demand, water is pumped to the upper reservoir
and stored, and during periods of high demand, the stored water is released
through the turbines to generate electricity. Pumped storage is currently the
only utility-scale energy storage technology available, although other storage
technologies are emerging.
5. J H. W  ., E  E E,
I.  ., P  D D   U S,
US 2050 R, V 1: T R 17-20 (2015), available
6. To achieve this balancing, the authors of the DDPP report assumed the
availability of 72 gigawatts (GW) of available pumped storage—50.4 GW
more than the 21.6 GW installed in the United States as of 2016. E-mails
From Jim Williams and Ryan Jones, Authors of the DDPP Report (Nov.
14-16, 2017) (on le with authors).
Authors Note: e authors would like to acknowledge the
       
 
Copyright © 2018 Environmental Law Institute®, Washington, DC. Reprinted with permission from ELR®,, 1-800-433-5120.
Still, the DDPP report did not fully account for the
potential for environmentally responsible expansion of
new conventional hydropower in the United States by
2050. Since that report was issued, the U.S. Department
of Energy (DOE) released the results of a new investiga-
tion,     
Renewable Electricity Source,7 that sheds new light on the
potential to expand both conventional and pumped stor-
age hydropower. To chart a path for achieving the results
envisioned in both the DDPP and DOE reports, this
Article identies new opportunities for sustainable growth,
explains environmental risks and requirements pertaining
to hydropower, and identies legal and market reforms
needed to capture a greater percentage of environmentally
responsible hydropower—both conventional and pumped
storage. We conclude that, based on its ability to provide
electricity-generation capacity, baseload power, peaking
power, energy storage, load following, and other essen-
tial generation features—together with its unique ability
to integrate other renewables such as wind a nd solar into
the grid—additional hydropower development above cur-
rent levels that meets modern environmental requirements
must be a component of any proposal to reduce the United
States’ dependence on carbon over the long term.
e DDPP report analyzes four distinct scenarios to
achieve signicant reductions in U.S. greenhouse ga s
(GHG) emissions by 2050, organized by the primary
energy choices for electricity: (1)renewable energy (High
Renewables Scenario); (2) nuclear (High Nuclear Sce-
nario); (3) fossil fuels with carbon capture and storage
(CCS) (High CCS Scenario); and (4)the Mixed Scenario
with roughly equivalent generation from all three primary
energy resources. In all but the High CCS Scenario, the
percentage share of hydropower in overall electricity gen-
eration decreases from current levels. In the Mixed Sce-
nario, which is the main case for the report, the percentage
share of hydro in overall electricity generation decreases
from 6.2% in 2014 to 5.6% in 2050 due to overall growt h
in electricity consumption but without substantial new
growth in hydropower resources.8 e report asserts that
hydropower is not expected to keep pace with electric-
ity growth because “development of new hydropower
resources is ... limited for sustainability reasons” as well as
resource constraints.9
It is correct that hydropower is more site-limited than
other resources; it requires a site where the natural ow
and falling of water can be captured. However, the DDPP
report does not explain its conclusion that hydropower is
limited due to “sustainability.” e report itself assumes
that the a mount of pumped storage must triple to eec-
tively balance non-dispatchable renewables and nuclear
7. DOE, H V: A N C  A’ 1 R-
 E S (2016) (DOE/GO-102016-4689) [here-
inafter H V], available at
8. W  ., supra note 5, tbl. 7.
9. Id. at 12.
power.10 Moreover, the report makes no mention of devel-
opment opportunities for conventional hydropower by
adding hydropower infrastructure at existing dams, mak-
ing capacity and eciency upgrades at existing hydropower
projects, implementing new technologies at low-head
dams that were once infeasible, and deploying emerging
marine a nd hydrokinetic (MHK) technologies to achieve
emissions reduction goals—all of which, if developed in
accordance with modern environmental requirements, can
enhance balancing of the grid, add dispatchable resources,
and meet “sustainability” considerations.
In its Hydropower Vision report, which was released
after the DDPP report, DOE estimates that hydropower
in the United States could feasibly grow from 101 giga-
watts (GW) of emissions-free11 generating and storage
capacity to nearly 150 GW by 2050, avoiding 5.6 billion
metric tons of carbon dioxide (CO2) emissions, saving
$209 billion in avoided global damages from CO2 emis-
sions, and creating more than 195,000 new jobs.12 While
much of this potential—consistent with the assumptions
in the DDPP report—comes from a signicant increase in
pumped storage,13 the DOE report nds opportunity for
13 GW of new conventional hydropower generation capac-
ity at new and existing facilities.14 e Hydropower Vision
report did not include MHK technologies, which represent
potential additional sources of hydropower development in
future years.
Beyond the modeled increases of hydropower in the
DDPP report, the DOE report demonstrates the con-
siderable role that hydropower—both conventional and
pumped storage —could play in nationwide decarboniza-
tion, and indicates that there are more available oppor-
tunities and pathways for the expansion of hydropower
than the DDPP report assumes to meet the nation’s cli-
mate goals. e legal pathways described in this Article
for hydropower provide additional approaches to achieving
the 80% reduction in GHG emissions by 2050 envisioned
in the DDPP report, provide additional options to pub-
lic and private decisionmakers (including options that are
less expensive or have greater economic, social, and envi-
ronmental benets), and increase the likelihood that the
required reduction can be achieved.
Realizing this full potential and even maintaining the
current hydropower eet will likely depend on overcoming
a number of impediments to hydropower in the United
States. Because expanding hydropower at federally con-
structed and operated dams is generally constrained by
10. See supra note 6.
11. While some research a sserts that reservoirs cre ated by dams are important
sources of GHG emissions, DOE’s Hydropower Vision report notes that
“[g]iven the state of scientic understanding and discourse, including per-
sistent uncertainties, the [report] does not attempt to address hydropower-
related biogenic GHG emissions.” H V, supra note 7, at
43. Moreover, the research analyzed reservoirs impounded by both hydro-
electric and non-hydroelectric dams, and only 3% of U.S. dams currently
have a hydroelectric component. us, adding hydropower at these existing
dams would not result in an increase in GHG emissions.
12. Id. at 3, 23.
13. See supra note 6.
14. H V, supra note 7, at xvii, 1, 7, 31.
Copyright © 2018 Environmental Law Institute®, Washington, DC. Reprinted with permission from ELR®,, 1-800-433-5120.

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