Hydropower

• Author: Charles R. Sensiba, Michael A. Swiger, and Sharon L. White
• Pages: 571-597

Page 571

I. Introduction

Hydropower, which generates electricity through falling

water,1 is the nation’s most established and mature renew-

able resource. It accounts for more than 6% of all electric-

ity generation and about one-half of all renewable power in

the United States.2 Hydropower resources serve an essen-

tial role supporting the electric grid by providing low-cost,

exible energy services, a nd a multitude of secondary ben-

ets, such as ood control, irrigation, water supply, and

recreational opportunities. Hydropower also is critical in

maintaining grid reliability and integrating variable gen-

eration resources, such as solar and wind, that continue

to come online in larger numbers. Because solar a nd wind

are intermittent resources, the electric grid ca nnot rely on

them in a ll hours; no other renewa bles but hydropower,

and to a lesser degree geothermal and biomass, are capa-

ble of quickly responding to the variable nature of wind

1. Hydropower also includes hydrokinetic technologies, which generate electric-

ity from waves, currents, and tides within a water body.

2. See U.S. Energy Information Administration, Hydropower Explained, http://

www.eia.gov/energyexplained/?page=hydropower_home (last updated June

13, 2017).

and solar, coming on- and o-line when needed to ensure

proper grid f unctioni ng.3

e Deep Decarbonization Pathways Project (DDPP)

report, Pathways to Deep Decarbonization in the United

States, recognizes the crucial role of hydropower to sustain

our transition to a decarbonized elect ric grid—particularly

with regard to hydropower pumped storage4 and its abil-

ity to balance 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

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 elevations.

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  ., P  D D  

U S, U.S. 2050 R, V 1: T R 17-20

(Deep Decarbonization Pathways Project & Energy and Environmental

Economics, Inc., 2015), available at http://usddpp.org/downloads/2014-

technical-report.pdf [hereinafter DDPP T R].

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

Chapter 22

Hydropower

by Charles R. Sensiba, Michael A. Swiger, and Sharon L. White

Summary

While the Deep Decarbonization Pathways Project reports recognize that pumped storage hydropower is crucial

to sustaining our transition to a decarbonized grid, they do not fully account for the potential for environmen-

tally responsible expansion of new conventional hydropower in the United States by 2050. ey conclude that

conventional hydropower is not expected to keep pace with electricity growth due to sustainability and resource

constraints. Yet, additional hydropower development above current levels—both conventional and pumped

storage—that meets modern environmental requirements must be a component of any proposal to reduce the

United States’ dependence on carbon over the long term. Realizing the full potential of hydropower and even

maintaining the current hydropower eet will likely depend on overcoming a number of impediments to hydro-

power in the United States. Such impediments include lengthy and complex regulatory requirements, failure

of the organized electricity markets to adequately compensate hydropower generators for the grid benets they

provide, environmental opposition to new hydropower, and interest in dam removal. ese challenges can be

overcome with targeted legal and policy reforms that would not roll back environmental standards.

Page 572 Legal Pathways to Deep Decarbonization in the United States

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, Hydropower Vision: A New Chapter for America’s 1st

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 chap-

ter 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. e chapter concludes that, based on its ability

to provide electricity-generation capacity, baseload power,

peaking power, energy storage, load following, a nd other

essential generation features— together with its unique

ability to integrate other renewables such as wind and solar

into the grid—additional hydropower development above

current levels that meets modern environmental require-

ments 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 gas

(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 ca se 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 growth

in electricity consumption but without substantial new

growth in hydropower re sources.8 e report a sserts 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

From Jim Williams and Ryan Jones, Authors of the DDPP Report (Nov.

14-16, 2017) (on le with authors).

7. DOE, H V: A N C  A’ 1 R

E S (2016) (DOE/GO-102016-4689) [hereinafter H-

 V], available at http://energy.gov/sites/prod/les/2016/10/f33/

Hydropower-Vision-10262016_0.pdf.

8. DDPP T R, supra note 5, tbl. 7.

9. Id. at 12.

and falling of water ca n be captured. However, the DDPP

report does not explain its conclusion that hydropower is

limited due to “sustainability.” e report itself assumes

that the amount of pumped storage must triple to eec-

tively balance non-d ispatcha ble renewables and nuclea r

power. 10 Moreover, the report makes no mention of devel-

opment opportunities for conventional hydropower by

adding hydropower infrastruct ure at existing da ms, mak-

ing capacity and eciency upgrades at e xisting hydropower

projects, implementing new technologie s at low-head

dams that were once infeasible, and deploying emerging

marine a nd hydroki netic (MHK) technologies to achieve

emissions reduction goals—a ll of which, if developed in

accordance with modern environmental requirements, ca n

enhance balancing of the grid, add dispatchable resources,

and meet “sust ainabil ity” considerations.

In its Hydropower Vision report, which was relea sed

after the DDPP report, DOE estimates that hydropower

in the United States could feasibly grow from 101 giga-

watts (GW) of emissions-free11 generating a nd 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 hydro-

power in the DDPP report, the DOE report demonstrates

the considerable role that hydropower—both conventional

and pumped storage—c ould play in nationwide decarbon-

ization, and indicates that there are more available oppor-

tunities and pathways for the expansion of hydropower

to meet the nation’s climate goals than the DDPP report

assumes. e legal pathways described in this chapter 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

10. See supra note 6.

11. While some research asserts that reservoirs created 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 persistent

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 hydroelectric

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.