1. The Role of Heat Storage
Nuclear + Renewables in a
Deeply Decarbonized Grid
The Role of Heat Storage
Charles Forsberg
 Massachusetts Institute of Technology
Cambridge, Massachusetts
Thursday, July 12, 1:30 PM
 Room 1-142, Carlson School of Management
321 19th Avenue South,
West Bank, UMN Minneapolis Campus, 55455

2. The Challenge: Changing Electricity Markets
Path Forward: Nuclear Energy Replacing Fossil Fuels in the Role of Dispatchable Energy Source
The Challenge: Changing Electricity Markets
Nuclear Power Systems for a Low-Carbon World
Base-load Nuclear Reactors with Variable Electricity Using Heat Storage
Assure Peak Electricity Generating Capacity
Low-Price Electricity to Heat Storage
Minnesota Wildcards
45, 8:15 2

3. The Challenge: Changing Electricity Markets A Low-Carbon World Changes Electricity Markets3

4. Energy is ~8% of world’s GNP, can’t afford to double
The Viability of Getting Off Fossil Fuels Depends Upon Economic Replacements
Energy is ~8% of world’s GNP, can’t afford to double
Economic constraint is as real for the U.S. as India
If economics are favorable, can change energy system in ten to twenty years
Gas Fracking has cut electricity prices in half in a decade
Google RE<C Experience: Unless High-Rate-of Return, Slow Deployment Rate
45, 8:15 4

5. Natural-Gas Combined Cycle
No Change In Energy Policy for 300,000 Years, Throw a Little Carbon on the Fire
Cooking Fire
Natural-Gas Combined Cycle
Low-Capital-Cost Power Systems, Labor & Money in Collecting Fuel: Wood or Natural Gas: Economic at Part Load 5 5

6. Nuclear, Wind, and Solar Are High-Capital-Cost Low-Operating-Cost Technologies
Site Independent Site Dependent
Must Operate Near Full Capacity for Economic Energy 6

7. Collapsing Prices Limit Use of
Electricity Price (Revenue) Collapse Limits Non-Dispatchable Wind and Solar Without Storage Hurts Nuclear, Wind, and Solar Economics, Helps Natural Gas
Impact of PV Expansion in California on Electricity Prices: Spring Day from 2012 to 2017
Collapsing Prices Limit Use of
Non-dispatchable PV
Varum Sivaram,, “A Tale of Two Technologies”, The Breakthrough Journal, No. 8 / Winter 2018.

8. APS (Arizona) Growth In Hours with Price Collapse from Solar and Wind
$10/MWh Far Below Cost of Nuclear, Wind and Solar

9. If No Fossil Fuels, Require New Assured Generating Capacity
APS (Arizona) Capacity Problem: Need More Generating Capacity to Backup Renewables Capacity (MWe): Capability to Produce Electricity to Avoid Blackouts
If No Fossil Fuels, Require New Assured Generating Capacity

10. Nuclear Power Systems for a Low-Carbon World10

11. Nuclear Plants are Designed
for Specific Markets
Historically designed for base-load electricity in a system designed to minimize cost to society
Nuclear: High-capital and low-operating cost
Fossil: Low-capital and high-operating cost
Some nuclear plants (France and Germany) have operated with variable output for decades
If market changes, modify plant to match what market needs

12. Strategy for Nuclear Power Plants With Non-Dispatchable Wind/Solar
Variable Electricity Demand
Sell
Sell
Buy
Assured Peak Electricity:
Combustible Fuels
(Nat. Gas, Oil, Biofuels, H2)
Power Cycle with Storage:
Buy and Sell Electricity
Heat
Nuclear Reactor (Base-Load)
Nuclear Replaces Fossil As Dispatchable Energy Source

13. Need Storage to Match Production with Demand,
But What Type of Storage? Heat or Work
Heat Production Electricity Production
Work Storage (Electricity): Hydro Pumped Storage, Batteries, Etc. 13

14. Heat Storage Is Cheaper Than Electricity Storage
Estimated Electricity Storage (battery, pumped hydro, etc.): $340 +/- 60/kWh(e) at Terrawatt Deployment Scale*
Greater than factor of 2 increase in electricity cost
If start with expensive materials, expensive product
DOE Battery Goal: $150/kWh(e) (Battery only)
DOE Heat Storage Goal: $15/kWh(t)
Cheap materials
Solar thermal plants have heat storage, PV does not
*O. Schmidt et al., The Future Cost of Electrical Energy Storage Based on Experience Rates,
Nature Energy, 2, Article 17110, July 10, 2017

15. Concentrated Solar Thermal Plants Installing Heat Storage at Gigawatt-Hour Scale
SolarReserve Crescent Dunes: 1.1 GWh Storage
But Solar Thermal Limited in Location: Direct Sunlight

16. Base-Load Nuclear Reactors with Variable Electricity Using Stored Heat LWRs with Steam Cycle Equivalent Systems for Other Reactor Types 16

17. Buy Low-Price Electricity Prairie Island and Monticello are LWRs
Base-Load Light Water Reactors with Steam Cycles
Variable Electricity
to Grid
Assured Peak
Generating Capacity
Buy Low-Price Electricity
Prairie Island and Monticello are LWRs 17

18. LWR With Heat Storage Base-Load Reactor (100%)
Low Electricity Prices (Excess production)
Steam turbine/generator at minimum electricity output
Excess steam to Storage
High Prices: Reactor and Stored Steam to Turbine

19. Six Heat Storage Technologies Couple to LWRs and Can Produce Peak Power Steam Accumulators and Sensible Heat Used in Existing Solar Thermal Systems
Steam Accumulators Sensible Heat Cryogenic Air Packed Beds Geothermal Hot Rock
Pilot Plant

20. Charlottenberg Power Station Steam Accumulator (Storage) for Variable Electricity: Berlin
Built 1929
Stored >600 t steam storage
Charge with steam from coal plant when low demand
50 MWe peak power from separate turbine
Sources: I. Kanakaris-Wirtl via Structurae, Science News Letter, A. G. Ter-Gazarian

21. Accumulator Steam to Turbines or Feed-water Heaters
Peak Electricity From Steam Accumulators Fast Response to Variable Electricity Demand
Accumulator Steam to Turbines or Feed-water Heaters
Steam
Generator
Pressurized
Water
Nuclear Plant Steam to Charge Accumulator
Accumulators charged with steam—heating water in accumulator
Accumulators operate sequentially
First discharge steam to high-pressure turbine or feed-water heaters
When pressure drops, discharge to lower pressure turbine or lower-temperature feed-water heater 21

22. Khi Solar I Steam Accumulators (2017) For Heat Storage (Courtesy of Abengoa)

23. Courtesy of Nevada Solar One
Store Heat in Low-Pressure Liquid or Solid
Oil-Based Sensible Heat Storage Coupled to Nevada Solar One Thermal Power System
Solar Heat Collection
Steam Plant
Oil Heat Storage
Courtesy of Nevada Solar One 23

24. Westinghouse Nuclear Sensible Heat Storage System Under Development
Steam heats oil
1-MWh(w) Heat Storage Module
Hot oil flows between concrete slabs
Heat storage in lower-cost thin concrete slabs
Reverse oil flow to send heat back to reactor as steam
60% Round-trip efficiency 24

25. Thermal Output From Rock
Geothermal Heat Storage System Create Artificial Geothermal Heat Source for Seasonal Storage Minimum Size ~0.1 GW-Year Storage: Intrinsically Large Scale
Thermal Input to Rock
Thermal Output From Rock
Oil
Shale
Hundreds of Meters
Rock
Permeable
Cap Rock
Nuclear Plant
Geothermal Plant
Fluid
Input
Fluid
Return
Pressurized Water for
Heat Transfer
Nesjavellir Geothermal power plant; Iceland; 120MW(e); Wikimedia Commons (2010) 25 25

26. Where is the cost of new nuclear?
Using Power Plant Turbine Implies Low-Cost Heat-to-Electricity
Where is the cost of new nuclear?
Turbine island small part of nuclear plant costs
About $500/kW capacity
Incremental increase in turbine hall capacity for heat storage will likely be a few hundred dollars per kW capacity
Less than gas turbine and pumped storage generation

27. Assure Peak Generating Capacity What If You Need Electricity and Storage Is Depleted?27

28. Solar, Wind, Hydro, and Storage Do Not Provide Assured Electricity
←Low Wind
Extended
Demand→
Dry Years→
←Night
McCrary Battery Storage Demonstration 28
What Provides Assured Capacity in a Low Carbon World?

29. Steam Boiler Seldom Used
Add Steam Boiler to Provide Assured Peak Capacity If Heat Storage Depleted Natural Gas, Oil, Biofuels, Hydrogen
If 1000 MWe Base and 200 MWe Peak, 1200 MWe Total
Steam boiler with added steam for 200 MWe Peak
Boiler only used if heat storage is depleted
Boiler: $ /kWe of peak electricity capacity
Today lowest-cost assured capacity is gas turbine at $600/kWe
Steam Boiler Seldom Used

30. Added Boiler Cost for Assured Capacity is Low After Buying Storage
Component
Adding Storage to LWR
Adding Capacity After Buy Storage
Feedwater
Incremental Addition
Turbine with Condenser
Electrical Generator
Boiler X
Cooling tower
Boiler $ /kWe (Simple Gas Turbine ~$600/kWe)

31. Low-Price Electricity to Heat Storage Use Resistance Heating to Convert Low-Price Electricity to Stored Heat Works With Most Heat Storage Options 31

32. So It Can Accelerate to Full Power When Prices Rise
Buying Low-Price Electricity for Heat Storage—Using All Excess Electricity
BUY
Avoids Selling Low-Price Electricity from the Nuclear Plant Turbine that Is Running at Minimum Output
So It Can Accelerate to Full Power When Prices Rise 32

33. Options To Convert Low-Price Electricity into High-Temperature Stored Heat
Convert to high-temperature stored heat
Deliver hot air to steam boiler when high electricity prices
Steam at LWR conditions (not lower-temperature heat)

34. Electric Heaters Heat Air
Hot Rock Option for Electricity to Stored Heat: Many Other Technical Options
Low-price electricity heats air that heats crushed rock
Blow cold air through hot rock to steam boiler to produce electricity
For LWR, use steam in main turbine for peak power (Cheaper than small stand-alone steam plant)
Siemens stand-alone plant with turbine-generator
Electric Heaters Heat Air
Steam Generator

35. LWR Storage System Economics
Maximize sales when high electricity prices
Assured capacity payments: Steam boiler half to a third the cost of competing option (gas turbine)
Buy low-price electricity (from turbine operating at minimum load and electricity gird) for stored heat
Factors to minimize costs
Incrementally larger steam turbine
Low cost of boiler for assured capacity
45, 8:15 35

36. Minnesota Wildcards
Industrial Energy Markets Minnesota Low-Carbon Energy Demand Estimates May Be Off by a Factor of 10 or More 36

37. Reactors With Heat Storage for Electricity; Have Basis for Assured Heat Supply to Industry

38. Hull-Rust-Mahoning Mine
Low-Carbon Future Could Make the Iron Range the Largest Industrial Complex in America (Change Process)
Iron ore + Coke + Limestone → Steel: Haul Iron Ore to Lower Great Lakes Where Coal and Limestone Located
Three great iron deposits
Minnesota/Wisconsin
Brazil
Australia
Future: Low-carbon steel production at mine
Direct reduction of iron (hydrogen and heat)
Most efficient hydrogen production method is high-temperature electrolysis
Heat input
Electricity input
45, 8:15
Hull-Rust-Mahoning Mine
Hibbing, Minnesota 38

39. Low-Carbon Cold-Winter Challenge
Electricity production in cold weather
Almost no solar (January/February)
Very low wind conditions
Low hydro (Ice and snow)
Nuclear production continues
In low-carbon world, winter has maximum electricity demand
Electricity replaces natural gas and LPG for home heating
Electric car recharging demand doubles
Low efficiency of batteries in cold weather
Passenger compartment heating
45, 8:15
Low-Carbon All-Electric Future May Be Unaffordable 39

40. Biofuels May Be the Low-Carbon Liquid Fuels Option40
Atmospheric
Carbon Dioxide
Biomass
Energy
Biomass
Nuclear
CxHy + (X + y 4
)O2
CO2 + ( 2
)H2O
Liquid Fuels
Fuel Factory
Cars, Trucks, and Planes
External Energy Input Doubles Liquid Fuel per Ton Biomass 40

41. Conclusions Electricity markets are changing
Can build base-load nuclear reactors with
Heat storage for variable electricity to the grid
Assured peaking capacity if heat storage is depleted
Low-price electricity to heat storage
Low-incremental cost for peak heat-to-electricity output
System characteristics may enable:
Nuclear to replace fossil fuels as variable energy source
Large-scale use of wind and solar (Reduce price collapse)
Economics is central

42. (Electricity Revenue)
Questions?
Markets
Electricity
Generation
Heat Storage
(Electricity Revenue)
Assured Capacity
(Capacity Revenue)

43. Biography: Charles Forsberg
Dr. Charles Forsberg is the Director and a Principle Investigator of the DOE Integrated Research Project on Fluoride-salt-cooled High-Temperature Reactors (FHRs). His research includes large-scale heat storage including Firebrick Resistance-Heated Energy Storage (FIRES) and utility-scale heat storage. 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. 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 300 papers. 43

44. https://doi.org/10.1016/j.tej.2018.03.008
Open Source

45. The Replacement for Fossil Fuels in the Electric Sector
Nuclear System for Variable Electricity, Assured Peak Electricity and Buy/Sell Electricity Heat Storage, Combustion Heater and Electricity-to-Heat Storage
The Replacement for Fossil Fuels in the Electric Sector

46. Firebrick Resistance-Heated Energy Storage (FIRES)
Converting Low-Price Electricity into Stored High-Temperature Heat for Industry and Power Production
BUY

47. 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
30, 30 47

48. FIRES Stores Heat in Firebrick to
Provide Hot Air to Industry or Utilities

49. FIRES Can Couple to Furnaces, Boilers, Kilns, Gas Turbines
Fossil Fuels + Air = Hot Air (Same Product as FIRES)
Industrial Furnaces and Boilers
Utility Boilers
Gas Turbines
Nuclear Air-Brayton Combined Cycle
High-Temperature FIRES: (1) Production of Brick, Concrete, Glass, and Metals and (2) Gas Turbines 49