Flibe (6Li2BeF4) Blankets to Integrate Heat
Production with Electricity Markets
Using Nuclear Brayton Combined Cycles
C. W. Forsberg1 and P. F. Peterson2
1Massachuestts
2University
1Department
Institute of Technology
of California at Berkeley
of Nuclear Science and Engineering; Massachusetts Institute of Technology
77 Massachusetts Ave; Bld. 24-207a; Cambridge, MA 02139; Tel: (617) 324-4010;
Email: [email protected]; http://web.mit.edu/nse/people/research/forsberg.html
Market Needs May Define Fusion Reactor
Power Cycles and Coolant Strategies
Understand Long-Term Electricity Markets
Base-load Electricity, Variable Electricity, Heat to Industry
Energy Conversion Systems to
Meet Market Requirements
Nuclear Air Brayton Combined Cycle (NACC)
Firebrick-Resistance Heated Energy Storage (FIRES)
Salt-Cooled Fusion and Fission Reactors
2
No Change In Energy Policy for 250,000
Years, Throw a Little Carbon on the Fire
Cooking Fire
Natural-Gas
Combined Cycle
3
Nuclear Energy Did Not Change Fossil
Fuel Energy Policy or the Market
4
New England Electricity Demand
Demand (104 MW(e))
• Low-capital-cost
High-operatingcost fossil plants
for variable energy
production
• High-capital-cost
Low-operating-cost
nuclear plants for
base-load
Time (hours since beginning of year)
Demand (104 MW(e))
If No Fossil Fuels Because of Concerns About 5
Climate Change, What Is Replacement For
Variable Electricity Production?
Variable
Electricity
Market
Base-load
Electricity
Market
Time (hours since beginning of year)
If Add Wind/Solar Base-Load Electricity Demand
May Disappear: The California Duck Curve
Solar Eliminates Mid-Day Demand For Other Electricity
Sources But More Variable Power Need When Sun Sets
Electricity Market Changes: Large Revenue
Boost If Produce Energy When Needed
Before and After Midday (Other Times for Wind)
Large-Scale Solar Collapses Electricity Prices in the
Middle of the Day—No Base Load Market
California Power Generation
Late Spring Weekend Day
New Energy Conversion System
to Address New Market Requirements
Understand Long-Term Electricity Markets
Base-load Electricity, Variable Electricity, Heat to Industry
Energy Conversion Systems to
Meet Market Requirements
Nuclear Air Brayton Combined Cycle (NACC)
Firebrick-Resistance Heated Energy Storage (FIRES)
Salt-Cooled Fusion and Fission Reactors
9
Salt-Cooled
High-Temperature
Fusion/Fission
Reactors
With Nuclear AirBrayton Combined
Cycle (NACC) and
FIRES
10
Modern Combined-Cycle Gas Turbines Have
Heat-To-Electricity Efficiencies of 60%
Most Efficient Heat to Electricity Technology and Improving Rapidly
• Used to meet
variable electricity
demand so replace
natural gas with
nuclear heat
• Must deliver nuclear
heat to compressed
air above front-end
jet-engine
compressor exit
temperatures of 300
to 450°C
11
In the 1950s the U.S. Launched the
Aircraft Nuclear Propulsion Program
Bomb Russia → Jet Engine → Salt Coolant → Reactor
Salt Coolants Designed to
Couple to Gas Turbines
12
Salt-Cooled Reactors Deliver Heat to
Power Cycle Between 600 and 700°C
FHR (Solid Fuel
and Clean Salt)
Molten Salt
Reactor (MSR)
Salt-Cooled
Fusion Reactor
Terrapower Design
13
Salt-Cooled Reactor with Nuclear AirBrayton Combined Cycle (NACC)
FIRES Stored Heat and/or Natural Gas
Fusion
Reactor
Gas
Turbine
Variable Electricity
And Steam
14
NACC Power System
Modified Natural-Gas-Fired Power Cycle
Filtered
Air
Compressor
Heat Recovery SG
Steam Sales or
Turbo-Generator
Turbines
Generator
Natural gas
or H2
Reactor Salt-to-Air Heaters
FIRES
Heat
Storage
Electric
Heating
15
Firebrick Resistance-Heated
Energy Storage (FIRES)
• Buy electricity when
electricity prices are less
than fossil fuels used by
industry (natural gas)
• Electrically heat insulated
mass of firebrick to very
high temperatures
• Use stored heat delivered as
hot air for two applications
– Industrial heat
– Peak electricity production
16
Stored Heat (FIRES) Replaces Natural Gas for LowCarbon System or Large Electricity Price Swings
17
Added Natural Gas or Stored Heat For
a Thermodynamic Topping Cycle
Topping Cycle: 66% Efficient for added Heat-to-Electricity; Future NACC
Topping >70%: Stand-Alone Combined-Cycle NG Plants 60% Efficient 18
Salt Fusion and Fission Reactors
Use Flibe (Li2BeF4) Coolant
Fusion
Clean
6Li BeF
2
4
FHR
MSR
Solid Fuel
and Clean
7Li BeF
2
4
Fuel Dissolved
in 7Li2BeF4
19
Rapid Growth of Interest in
Fission Salt-Cooled Reactors
• United States
– Multiple startup companies
– Federal government
– Universities
• China (SINAP)
Irradiations
MIT
Corrosion
Loops (UW)
Thermal
Loops (UCB)
(Simulants) 20
Flibe Coolant Development
Major Component of Work
• Massive overlap between fission and fusion
coolant requirements
• Important differences fusion vs. fission
– Tritium production three orders of magnitude larger
– Tougher challenge to meet tritium emission limits
– Must recover and recycle tritium efficiently
– May use different materials of construction
21
Large Incentives for
Fusion and Fission
on Work On Flibe
Coolant Challenges
FHR
Gas
Turbine
22
Biography: Charles Forsberg
Dr. Charles Forsberg is the Director and principle investigator of the HighTemperature Salt-Cooled Reactor Project and University Lead for the Idaho
National Laboratory Institute for Nuclear Energy and Science (INEST)
Nuclear Hybrid Energy Systems program. He is one of several co-principle
investigators for the Concentrated Solar Power on Demand (CSPonD)
project. He earlier was the Executive Director of the MIT Nuclear Fuel Cycle
Study. 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 hydrogen production and nuclear-renewable
energy futures. He received the American Nuclear Society special award
for innovative nuclear reactor design on salt-cooled reactors and the 2014
Seaborg Award. 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 has published
over 200 papers.
http://web.mit.edu/nse/people/research/forsberg.html
23
Market Change
Requires Rethinking
Fission and Fusion
Power
• Market change bad for
high-capital-cost lowoperating-cost nuclear,
wind, and solar
• Not a problem for lowcapital-cost highoperating-cost natural gas,
shut down when low
prices
Base-Load NACC Operations
• 42% Base-load efficiency if
optimized for base-load
power (GE 7FB Gas
turbine)
• Process description
–
–
–
–
–
–
Compress filtered air
Heat air with salt coolant
Turbine for power
Reheat air with salt coolant
Turbine for power
Hot air to heat recovery
steam generator with steam
for electricity or industry
– Exhaust air up stack
25
Peak Power NACC Operations
• Incremental heat-toelectricity efficiency 67%
• Thermodynamic topping
cycle more efficient than
stand-alone natural gas
combined cycle plant (60%)
• Process
– Add natural gas or stored
heat to “low-temperature”
670°C compressed air
– Added power from second
gas turbine
– Higher temperature to heat
recovery steam generator
with higher-temperature
steam: more power
26
FHR with NACC and FIRES
Buys and Sells Electricity
• If >50% difference
in electricity prices,
buy electricity when
low prices to sell at
higher prices
• Direct competitor
to batteries and
pumped storage
• Unlike batteries and
pumped storage,
assured capacity
with NG or oil peak
power
27
Firebrick Recuperator for Heat
Recovery Steam Generator
Diverts Gas-Turbine Hot Gas to Heat
Storage When Low-Priced Electricity
Heat Storage Sends Added Hot Air to
HRSG When High Electricity Demand
NACC with Firebrick Recuperator
Very Low Cost (Low-Pressure, Lower Temperature)
Heat Storage Relative to Other Storage Technologies
29
Lower-Temperature
Low-Pressure Firebrick
Recuperator Stores Heat
and Varies Heat to HRSG
• Hot exhaust from turbine
can heat firebrick rather
than generate steam and
then go to stack
• Cold air can be blown
through firebrick to provide
added hot air to HRSG to
generate more steam—
greater variable power
• Second storage system with
very cost (low-pressure)
heat storage system
30
Implications of Ultra-Low
Heat-Storage Costs
• Address weekday/weekend storage challenge
– Electricity demand lower on weekend but the sun
shines and wind blows
– Large fraction of cheap electricity on weekend
– System stores weekend energy for the weekday
• If very cheap or negative electricity, option to
add electric heaters to dump cheap electricity
as heat into firebrick recuperator