Nuclear Reactors with Heat Storage to

Boost Revenue and Replace Fossil Fuels

Charles Forsberg

Massachusetts Institute of Technology

Email: cforsber@mit.edu

National University Consortium Workshop

Innovations in Advanced Reactor Design, Analysis and Licensing

North Caroline State University

September 17-18, 2019

Workshop Proceedings

Heat Storage for Gen IV

Reactors for Variable

Electricity from Base-load

Reactors

https://www.dropbox.com/s/262cecf0vdc3x8q/Workshop%2

0Heat%20Storage%20Main%20Report-Final.pdf?dl=0

2

3

Energy Markets

Two Primary Energy Forms:

(1) Heat and (2) Work (Electricity)

Two Changes:

(1) Addition of Wind and Solar and

(2) Goal of Low-Carbon Energy System

Most Energy Is Consumed As Heat

Electricity

Heat

Industrial Heat Demand Twice Electricity Demand 4

Heat is Cheap; Electricity is Expensive

Thermodynamics 101 of Power Cycles

Multiple Units of Heat → One Unit Electricity

1 Unit of Electricity → One Unit of Heat

+ Power Plant

Electric Resistance

Heater

Homes Heated with Natural Gas and Oil Because

Electric Heat Typically 3 to 6 times More Costly

+

5

Technology LCOE: $/MWh(e) LCOH: $/MWh(t)

Solar PV: Rooftop Home 187–319 187-319

Solar PV: Crystalline Utility 46–53 46-53

Solar PV: Thin Film Utility 43–48 43-48

Solar Thermal Tower w Storage 98–181 33-60

Wind 30–60 30-60

Natural Gas Peaking 156–210 20-40

NG Combined Cycle 42–78 20-40

Nuclear 112–183 37-61

Levelized Cost of Electricity (LCOE): (Lazard 2017)

and Levelized Cost of Heat (LCOH)

Nuclear Is the Low-Cost Dispatchable Heat Source6

Large-Scale Solar or Wind Causes Price Collapse

and Higher Prices at Other TimesDo Not Want To Sell Electricity at Negative Prices

Impact of Added Solar PV on California Wholesale Prices:

Value of Wind and Solar Decrease With Scale

Added

Solar

7

Electricity Price (Revenue) Collapse Limits

Non-Dispatchable Wind and Solar Without Storage

Saturate Market Even If Large Subsides

Varum Sivaram,, “A

Tale of Two

Technologies”, The

Breakthrough Journal,

(8), Winter 2018.

Why Large-Scale Wind & Solar Increase Retail Electricity Prices 8

Produce Electricity Produce Heat

Low-Carbon System Economics: High Capital Cost and Low Operating Cost

Operate At Half Capacity Doubles Energy Costs

Must Operate These Technologies Near Full Capacity 9

10

Rethinking System Design for Heat Generating

Technologies in a Low Carbon World

Nuclear, Concentrated Solar, Geothermal, Fossil Fuel

With Carbon Capture and Fusion (Future)

What a Low-Carbon Electricity System Needs

• Sell dispatchable electricity

– Low cost

– Assured generating capacity for peak loads

• Buy very-low-price electricity from wind and solar PV at times of

excess production: Sets a minimum price that improve economics

• Operate nuclear reactors and other heat-generating technologies

at base-load to minimize costs

Replace the Storage, Dispatchability and Production

Characteristics of Fossil Fuels

11

Require a New System Design

Heat to Electricity

Sell Dispatchable

Electricity Buy Low-Price

Excess Electricity

and Convert to Heat

• Base-load

nuclear heat

• Heat storage for

peak electricity

production

• Low-price

electricity to heat

storage

• Backup furnace

for assured peak

capacity

Electricity Market (Grid)

Assured Peak

Capacity

(H2 and Biofuels)Industrial Heat Load12

Nitrate-Salt Heat Storage is Done at the Gigawatt-hour Scale at Concentrated Solar Power Plants

Nitrate Salt Heat Storage Proposed for Sodium, Salt and Helium Cooled Reactors

Solana Generating Station

(2013, U.S., ~4200 MWh(t)) Cerro Dominador Project (under

construction, Chile, ~4800 MWh(t))

13

Pilot Plant

Steam Accumulators

Sensible Heat

(Hot salt, etc.)

Hot Cement

Geothermal

(Seasonal)

Hot Rock

Low-Cost Heat Storage Couples to Nuclear: Same Technologies as Concentrated Solar Power

14

Nitrate Salt

Pilot Plant

Heat Storage Is Cheaper than Electricity Storage (Batteries, Pumped Hydro, etc.) with Many Different Technologies

• DOE heat storage goal:

$15/kwh(t)

• Battery goal

$150/kWh(e), double if

include electronics

• Difference is raw

materials cost

• EPRI estimates

batteries are 3 to 4

times more expensive

per kWh(e)

Storage Technologies

(Italic CSP Commercial)

LWR

Option

Sodium, Salt,

Helium Options

Pressurized Water X Limited

Geothermal X Limited

Counter Current Sat Steam X Limited

Cryogenic Air X X

Concrete X X

Crushed Rock X

Sand X

Oil X Limited

Cast Iron X

Nitrate Salt X

Chloride Salt X

Graphite (Helium and Salt) X

15

If Heat Storage, Buy Excess Low-Price Electricity

and Convert to Stored Heat for Later Use

• When low-prices– Nuclear generator and grid

electricity to heat storage

– Electric resistance heaters

• Low-cost storage option– Same equipment (grid connections,

transformers, switchgear) to buy

and sell electricity

– Own storage system and electricity

peaking capability

– Low-cost incremental addition to

heat storage capacity

Improves Nuclear, Wind and Solar Economics16

DayLo

ad

/Ge

ne

rati

on

(M

W) Seasonal

Surplus

Seasonal Deficit

S. Brick -California Case Study: Clean Air Task Force

Massive Seasonal Mismatch Between Production and

Demand if Use Just Renewables: California Example

Smoothed Daily

CAISO Load (MW)

• Build renewable

output over one

year to match

consumption

• Seasonal

mismatch in timing

between

production and

demand

• Expensive storage

requirements

Smoothed Daily

Renewable

Generation (MW)

17

Require Assured Generating Capacity

Heat to Electricity

Sell Dispatchable

Electricity Buy Low-

Price Excess

Electricity and

Convert to Heat

Electricity Market (Grid)

Furnace or Boiler for

Assured Peak Capacity

(H2 and Biofuels)Industrial Heat Load

Backup for

Depleted

Storage

18

If Heat Storage, Option to Buy Furnace or Steam

Generator for Assured Peak Power

• All storage devices can become

depleted but need assured peak power

• Burns (1) natural gas or (2) low-carbon

biofuels and hydrogen with heat to

storage system

• Low-cost option

– Use storage electricity peaking capability

(turbine generator)

– Half to third the cost of backup gas turbine

for assured capacity

Seldom Used & Low-Carbon Fuel Options19

Same Nuclear System for Co-GenerationProduce Variable Heat and Electricity

20

• Industrial heat demand exceeds electricity output – Electricity costs 4 to 6 times the cost of heat, expensive to electrify industry

• Large incentives for nuclear cogeneration– Fossil cogeneration plants sometimes vary heat delivery to maximize electricity sales

when prices are high. Same option for nuclear co-generation to provide added assured

peak generating capacity

– Storable manufactured fuels (hydrogen, biofuels) have massive heat and electricity

inputs. Vary production with electricity prices that couples utility and transportation

energy markets

• Co-generation enables optimization of combined electricity,

industrial, and transportation energy markets to minimize total

costs

Change In Energy System Goals May Support a

New Nuclear Plant Design Similar to CSP Systems

Solana Generating Station

(2013, U.S., ~4200 MWh(t))

21MIT/INL Workshop in 2020 on this Design Option

Conclusions

22

• Electricity market is changing: Volatile prices

– Deployment of non-dispatchable wind and solar PV

– Goal of low-carbon economy

• Low-carbon world requires a replacement for fossil fuels as (1) Energy source, (2) Storable energy and (3) Dispatchable energy

• Require heat storage (kWh) on the gigawatt-hour scale to buy and sell electricity to maximize revenue

• Require assured peak electric generating capacity (kW)

• New nuclear system design to meet requirements and enable larger-scale nuclear, wind and solar

Questions

23

Biography: Charles Forsberg

Dr. Charles Forsberg research areas include Fluoride-salt-cooled High-

Temperature Reactors (FHRs) and utility-scale heat storage including Firebrick

Resistance-Heated Energy Storage (FIRES). He teaches at MIT the fuel cycle

and nuclear chemical engineering classes. Before joining MIT, he was a

Corporate Fellow at Oak Ridge National Laboratory. He is a Fellow of the

American Nuclear Society, a Fellow of the American Association for the

Advancement of Science, and recipient of the 2005 Robert E. Wilson Award

from the American Institute of Chemical Engineers for outstanding chemical

engineering contributions to nuclear energy, including his work in waste

management, hydrogen production and nuclear-renewable energy futures. He

received the American Nuclear Society special award for innovative nuclear

reactor design and is a Director of the ANS.. Dr. Forsberg earned his bachelor's

degree in chemical engineering from the University of Minnesota and his

doctorate in Nuclear Engineering from MIT. He has been awarded 12 patents

and published over 300 papers.

24http://web.mit.edu/nse/people/research/forsberg.html

Abstract: Nuclear Reactors with Heat Storage to

Boost Revenue and Replace Fossil Fuels

The electricity grid is changing because of (1) the addition of wind and solar that creates volatile electricity

prices including times of zero-priced electricity and (2) the goal of a low-carbon world that requires replacing

fossil fuels that provide (a) energy, (b) stored energy and (c) dispatchable energy. Wind and solar provide

energy but not the other two other required energy functions that are provided fossil fuels. Nuclear energy with

heat storage can fully replace fossil fuels including providing dispatchable electricity. Heat storage enables

reactors to maximize revenue by selling electricity at times of high prices and buying electricity that is

converted to stored heat at times of low or negative electricity prices. These systems enable a base-load nuclear

plant to provide peak electricity production that is significantly above the base-load electricity production

capacity. These options were examined at the July 23-24, 2019 MIT/INL/Exelon workshop: Heat Storage for

Gen IV Reactors for Variable Electricity from Base-load Reactors: Changing Markets, Technology, Nuclear-

Renewables Integration and Synergisms with Solar Thermal Power Systems. The results from this workshop are

described that include (1) the institutional requirements, (2) examination of heat storage systems capable of

gigawatt-hour heat storage and (3) the path forward. The changes in the market may make traditional base-load

nuclear reactors uneconomic. The most economic (profitable) reactors may be those that best integrate the

reactor with heat storage and the power cycle because of the potential to double total plant revenue.

25

References

1. C. W. Forsberg, H. Gougar, and P. Sabharwll, Heat Storage Coupled to Generation IV Reactors for Variable Electricity

from Base-load Reactors: Workshop Proceedings, ANP-TR-185, Center for Advanced Nuclear Energy, Massachusetts

Institute of Technology INL/EXT-19-54909, Idaho National Laboratory, 2019

2. C. W. Forsberg, “Variable and Assured Peak Electricity from Base-Load Light-Water Reactors with Heat Storage and

Auxiliary Combustible Fuels”, Nuclear Technology March 2019. https://doi.org/10.1080/00295450.2018.1518555

3. C. Forsberg and P. Sabharwall, Heat Storage Options for Sodium, Salt and Helium Cooled Reactors to Enable Variable

Electricity to the Grid and Heat to Industry with Base-Load Operations, ANP-TR-181, Center for Advanced Nuclear

Energy, Massachusetts Institute of Technology, INL/EXT-18-51329, Idaho National Laboratory

4. C. Forsberg, Stephen Brick, and Geoffrey Haratyk, “Coupling Heat Storage to Nuclear Reactors for Variable Electricity

Output with Base-Load Reactor Operation, Electricity Journal, 31, 23-31, April 2018,

https://doi.org/10.1016/j.tej.2018.03.008

5. The Future of Nuclear Energy in a Carbon Constrained World, Massachusetts Institute of Technology,

https://energy.mit.edu/wp-content/uploads/2018/09/The-Future-of-Nuclear-Energy-in-a-Carbon-Constrained-World.pdf

6. C. Forsberg, K. Dawson, N. Sepulveda, and M. Corradini, Implications of Carbon Constraints on (1) the Electricity

Generating Mix for the United States, China, France and the United Kingdom and (1) Future Nuclear System

Requirements, MIT-ANP-TR-184 (March 2019)

7. C. W. Forsberg (March 2019): Commentary: Nuclear Energy for Economic Variable Electricity: Replacing the Role of

Fossil Fuels, Nuclear Technology, 205, iii-iv, DOI:10.1080/00295450.2018.1523623

26

Nuclear plant design has followed coal plant design with the

reactor integrated to the power block that includes the turbine

generator. There is an alternative design, the nuclear reactor is in

the security zone with the power block outside the security zone

coupled to gigawatt-hour heat storage systems. Changes in

nuclear plant requirements may make this the preferred option for

future reactors. Electricity markets are changing that creates

incentives for adding heat storage but gigawatt-hour heat storage

systems are very large and couple to the power block. The storage

system size will likely exceed the physical size of the nuclear

power plant and the power block. If the power station includes

heat storage, the reactor is a heat production system that converts

cold salt to hot salt and is effectively decoupled from the

production of electricity or sending heat to industry—avoiding

the complications from directly coupling the reactor and the grid

while boosting grid resiliency. Second, nuclear requirements

(security, construction, licensing, operations, etc.) raise the costs

of anything tightly coupled to the nuclear reactor. With separation

of the reactor from power block, the nuclear reactor has the

nuclear licensing, construction, and security costs. The power

block and heat storage are designed, licensed, built and operated

to normal industrial standards with a clear over-the-fence

separation from the nuclear systems. The workshop is a first look

at this alternative reactor design option that is applicable to

multiple reactor types.

Workshop (Spring 2020):

Separating Nuclear Reactors

from the Power Block with Heat

Storage: A New Power Plant

Design Option

27

DayLo

ad

/Ge

ne

rati

on

(M

W) Seasonal

Surplus

Seasonal Deficit

S. Brick -California Case Study: Clean Air Task Force

Greater Challenge in a Low-Carbon World If Electrify

Home Heating and Industry: California Example

Smoothed Daily

CAISO Load (MW)

• Add electric

winter heating

load at worse

time for wind and

solar

• Add flat industrial

load

• No good estimates

of impacts of

heating loads

Smoothed Daily

Renewable

Generation (MW)

28

Add Heating Load

Nuclear-Geothermal Heat Storage System

Nuclear Heat to Create Artificial Geothermal Heat Source

Oil Shale

Oil Shale

Hu

nd

red

s o

f M

ete

rsH

un

dre

ds

of

Me

ters

Rock

Permeable

Cap Rock

29

Geothermal PlantNuclear Plant

Fluid

Return

Thermal

Input to

Rock

Thermal

Output From

Rock

Fluid

Input

Nesjavellir

Geothermal

power

plant;

Iceland;

120MW(e);

Wikimedia

Commons

(2010)

Conventional

Combined Cycle Gas

Turbine

Nuclear Air-Brayton Combined Cycle (NACC) to

Replace Natural Gas Turbine Combined Cycle

30

• Gas Turbine Advantages

– Variable Electricity to

the Grid

– Fast Response

• Nuclear Equivalent

Proposed

– Heat Storage

– Peaking Power

Wind/Solar without Cheap Natural Gas & Gas Turbines is Expensive

• Europe

– No cheap natural gas

– Push for renewables

– Expensive electricity

• If use wind and solar,

require affordable

dispatchable electricity

• Require Hydro

(Northwest) or Cheap

Natural Gas (Great Plains)

NACC With Heat Storage and Thermodynamic Topping Cycle

32

NACC Performance Parameters

Turbine

1&2 Exit

Temp

Turbine 3

Nominal

Exit Temp

Turbine 3

Boosted

Inlet

Temp

Base

Efficiency

Fraction

Base from

Steam

Hydrogen

Burn

Efficiency

Combined

Efficiency

Brayton

Gain

Overall

Gain

Sodium Near-Term System (Nominal Inlet Temperature 773 K (500°C)

680.5 K 640.5 K 1100 K 32.8% 18% 71.1% 48.4% 1.464 2.522

680.5 K 640.5 K 1700 K 32.8% 18% 74.2% 60.4% 2.347 5.744

Molten Salt Advanced System (Nominal Inlet Temperature 973 K (700°C)

792.5 K 722.5 K 1100 K 45.5% 24% 74.5% 51.1% 1.168 1.403

792.5 K 722.5 K 1700 K 45.5% 24% 75.0% 61.6% 1.834 3.070

Incremental Combustion

Fuel to Electricity Efficiency

Power Gain: First Case Brayton

Output 46.6% Higher When Peak Mode

34

Option to Add Heat Storage Between Brayton Cycle and Heat Recovery Steam Generator

Heat Recuperator

Options

• Traditional Firebrick

• Hot Concrete

• Crushed Rock

35

36

Three Electricity Generating System Options for

a Low-Carbon World that Meet the Three

Requirements:

Electricity Generation

Energy Storage

Assured Peak Generating Capacity

Nuclear Energy with Heat Storage and Backup

Furnace (Biofuels, Hydrogen, etc.)

Heat Generation to Heat Backup Boiler for

Electricity and Storage Storage Depleted Storage

Concentrated Solar Power (CSP) has Same System Design 37

Generation Electricity Backup GT for

Storage Depleted Storage

Wind / Solar PV System With Electricity Storage

and Backup Gas Turbine

McCrary Battery Storage Demonstration

Seasonal Solar & Wind Input Requires Significant

Operation of Gas Turbine Backup (Biofuels and H2) 38

Fossil Plant with Carbon Capture

and Sequestration

• Post combustion

capture CO2

• 240 MW

– Added to Unit 8

(654 MW)

– 37% of Unit 8

emissions

• 90% CO2 capture

Petra Nova (Joint venture): NGR Energy and

JX Nippon Oil and Gas Exploration

39

Comparison of the Three Energy Options

Some Mixture Likely Where Choices Depend upon Location

Option/

Characteristic

Nuclear* with

Storage + Fuel

Wind/Solar PV*

With Storage + Fuel

Fossil with Carbon

Sequestration

1. Base-load Fuel cost Low ~0 High

2. GWtotal/GWpeak 1 >2 1

3. Low-carbon fuel

demand (H2, biofuels, etc.)

Low High None

4. Location Dependent No Yes Yes

Numbered Notes below coupled to characteristics

2. GW(e) nameplate rating divided by GW(e) assured peaking capacity. Wind and solar PV total generating capacity equals Wind/Solar PV + battery + gas turbine but if extended low

wind/solar conditions, the only assured capacity is the gas turbine.

3. Low-carbon fuel required for assured peaking capacity when storage is depleted. For nuclear this peaking capacity above base-load nuclear. For wind/solar this is total power because

no assured base-load capability from wind and solar.

4. No location dependency for nuclear. Wind/Solar depend upon local wind and solar conditions. Fossil depend upon sequestration sites.

*Concentrated Solar Power systems have some of the characteristics of nuclear systems and some of the characteristics of solar PV

40

• Mismatch between full production and electricity demand implies more

storage and higher costs; Nuclear with storage has the closest match

Lowest Cost System Depends upon (1) System Option Cost

and (2) Best Match Between Production and Demand

41