Nuclear Reactors with Heat Storage to
Boost Revenue and Replace Fossil Fuels
Charles Forsberg
Massachusetts Institute of Technology
Email: [email protected]
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
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