University:
Boston University
Course:
CAS EC 323 | Behavioral Economics
Academic year:

2023
Views:

7

Pages:

21
Author:

Lafuentedqri

High Temperature (Industrial) Heat Pumps: An Untapped US Industrial Process Energy Efficiency Opportunity Fundamentals of Heat Pumps Energy In: Work or Heat Heat Useful (Sink), T sink COP heating = Qsink/Energy In Qsink COP carnot, heating = Tsink / (Tsink – Tsource) Heat Pump Qsource Heat Source, Tsource Heat Pump Lift Temperature = Tsink - Tsource COP heating = Carnot Eff. * COP carnot, heating Heat pump Carnot Eff. ranges from ~30 - 60% Less lift temperature equals greater heat pump efficiency Typical HTHP heat sources and sinks Space Heating 30 C to 70 C Steam 100 C to 220 C Drying Process 100 C to 250 C Process Heat Hot water 50 C to 120 C Heat Pump Ground Air Water Cooling Tower Process Waste Exhaust Heat Process vapor condensation US DOE Heat Pump Program & IEA Annex 21 Study IEA Annex 21 Study (1993 – 1995) - Industrial Heat Pumps: Experiences, Potential and Global Environmental Benefits Ø 8 countries collaborated Ø 35 processes evaluated for IHP potential across all 8 countries Ø Each country performed IHP market study (see right hand box for US IHP Study) US IHP Market Study • US study screened 42 processes; 26 found for economic IHP potential • 8 processes accounted for most (68%) of IHP economic energy savings Ø Corn milling Ø TMP pulp Ø Unbleached kraft linerboard Ø Beet sugar refining Ø Bleached kraft pulp Ø Bleached kraft pulp and paper Ø High fructose corn syrup Ø Synthetic rubber US DOE 1995 Industrial Heat Pump Market Study found 2-5% net process heat savings; 170 - 350 TBtu/yr Average Industrial Energy Prices 1995 (2019$) 2019 Natural Gas ($/MMBtu) $6.56 $3.85 Electricity Price (cts/kW-hr) 4.28 cts 6.83 cts Electricity Price ($/MMBtu) $22.16 $20.00 Electricity/Gas Price Ratio 3.37 5.19 Study 1995 Energy Prices Recent energy prices are lower than in 1995 4 High Temperature Heat Pump Types Cycle Type High Temperature Heat Pump Type Closed Cycle Mechanical vapor compression heat pump Closed Cycle Heat activated heat pump: absorption or heat transformer Open Cycle Mechanical vapor re-compression (MVR) heat pump Open Cycle Thermal vapor re-compression (TVR) or steam ejector heat pump Absorption heat pump Closed Cycle Mechanical Vapor Compression Heat Pump Mechanical vapor recompressor Steam ejector Heat Integration and Proper Placement of HTHPs with PINCH technology Example Composite curves of heating and cooling streams Example Grand Composite Curve Heat Integration and Proper Placement of HTHPs with PINCH technology Pinch Point Example Composite curves of heating and cooling streams Example Grand Composite Curve Heat Pump should pump heat around pinch point Q+W Heat delivery Heat Pump W Q Heat extraction Pinch Point Key IHP barriers in the US Low level of awareness of the technical possibilities and economic feasibility among end users, engineering firms, suppliers, etc. Lack of knowledge on how to integrate heat pumps into existing industrial processes Lack of best practice examples to create trust in new type of process heating solution Most times one-off, tailor-made design and many times need to be integrated to process Long payback on investment due to low natural gas price and/or high electric to natural gas price ratio Competing process heating energy efficiency options Heat storage could be required Existing technology limited by heat pump output temperature (~160 deg. C, 320 deg. F) Limited domestic equipment suppliers – EU, Japan Mechanical Vapor Compression Heat Pump Payback versus Heat Pump Lift Temperature Investment Payback (Years) 15 Assumptions Waste steam heat = 100 deg C Heat pump size = 1 MW Heat pump cost = $200,000 Hours of operation = 8,500 hrs/yr Heat exchanger delta T = 10 deg C Carnot efficiency = 45% Maintenance cost = 3% of capital cost Electricity price = 6.83 cts per kW-hr Natural gas price = $3.85 per MMBtu 10 Heat pump working fluid limit, 160 deg C 5 0 10 20 30 40 50 Heat Pump Lift Temperature (degrees C) 60 What are major technology opportunities that are NOT currently being researched? Advanced High Temperature Heat-Activated Heat Pumps – Type 1 and 2 Thot [Type 2] [Type 1] Tuseful Tsource Tambient Absorption Heat Pump COP ~ 1.6 Heat Transformer Heat pump lift temperature COP ~ 0.5 Example Economics for 1 MW Heat Transformer Q sink = 1 MW @ T sink = 150 deg. C (steam) Q source = 2 MW @ T source 100 deg. C (steam) Q cold = 1 MW @ T cold = 30 deg. C Heat Transformer Cost = $1.5 Mil ($1,500 per kW, pilot unit) Annual maintenance cost = 2% of 1.5 Mil = $30,000 per year Electricity requirements = 40 kW Electricity price = 6.83 cts per kW-hr Operating hours = 8,760 hrs per year Annual electricity cost = $24,000 per year Total operating cost = $54,000 Natural gas cost = $3.85 per MMBtu (avg. US industrial price, 2019) Steam cost = $5.90 per 1000 lb steam Steam cost savings1 = $194,000 per year COP ~ 0.5 Tuseful - Tsource <= 0.8 * (Tsource- Tcold) T useful Q source T source Payback = $1,500,000 / ($194,000 - $54,000) = 10.7 yrs Note 1 – assume 1MW Heat Transformer produces 3750 lbs steam per hr @ 150C and avoids boiler steam and cooling tower costs @ $5.90 per 1000 lbs steam. Boiler steam costs account for energy cost (natural gas cost and boiler combustion efficiency) and chemical cost needed to treat boiler water. Private communication Riyaz Papar, January, 2021 Heat Transformer T cold Q useful Q cold Heat Transformer Payback versus Natural Gas Price 10 8 Investment Payback (Years) He Assumptions Waste steam heat = 100 deg C Heat pump size = 1 MW Heat pump delivery temp. = 150 deg C Heat pump lift temp. = 60 deg C Hours of operation = 8,760 hrs/yr Maintenance cost = 2% of capital cost Electricity consumption = 4% of heat delivery Electricity price = 6.83 cts per kW-hr 6 sfo rm er $1, 200 / < 5 Year Payback 4 at tra n spe kW c if ic c ap ita l co st = $1 ,50 0/ kW $900 / kW Avg. US industrial price (2019) 2 0 2 4 6 Natural gas price ($ per MMBtu) 8 10 Emerging heat-activated heat pump technology QPinch Heat-activated heat pump by reversible chemical reaction phosphoric acid to diphosphoric and water H4P2O7 + H2O ⇌ 2H3PO4 Tsink up to 220 deg. C Minimal electricity requirements; waste heat-driven Lift temperature= 40 - 100 deg. C Multi megawatt demos planned; independent validation needed for: - Cost and performance - Reliability and material durability - Impact on process control What are the most critical research priorities in HTHPs? • Heat-activated heat pumps R&D should focus on: Ø Developing various Type 1 and 2 cycles and configurations to demonstrate performance and cost Ø Demonstrate heat pump material durability in actual industrial settings and conditions. Ø Demonstrate heat pump operability and reliability in varied industrial processes to prove out economics Ø Prove heat pump working fluids are safe and environmentally benign • Technology development R&D targets Ø Specific capital cost (total installation) < $1,000 per kW Ø Heat delivery > 200 deg. C and ideally > 250 deg. C Ø Lift temperature up to 100 deg. C Conclusions There’s reason to be optimistic about High Temperature Heat Pumps 1. New perspective by industry: Companies that are serious about decarbonizing their energy footprints will consider HTHPs if they yield significant (>5 – 10%) energy savings and decarbonization at a reasonable payback, e.g., less than 5 years. 2. R&D justified to build domestic High Temperature Heat Pump industry: Advanced heat-activated heat pumps could be a game-changer to greatly expand the number of economic opportunities in the US process industries - even with only modest increases in natural gas prices. Cost-shared R&D in the US should help build the domestic supplier base for high temperature heat pumps. 3. Technology development is not enough: Further technology development is needed and justified but needs to be coupled with effective energy policy and/or incentives to motivate all participants in HTHP market – end users, vendors, engineering firms and energy efficiency program administrators/utilities. Mechanical vapor compression heat pumps; reference Cordin Arpagaus, 2020 Ratio of Industrial electricity/gas Price Market challenges Electricity to gas price ratio 1.0 1.5 2.0 2.5 • 3.0 • 3 .5 4.0 • 4.5 5.0 ■ ■ ■ For small scale industrial end-users with 2 GWh/a to 20 GWh/a electricity 3 GWh/a to 28 GWh/a gas А2ЕР Briefing: Advances in industrial heat pumps - 3 SeptemЬer 2020 23 IHP types: Pros and Cons. What are the pros and cons of various HTHP types? Type Prime Mover Closed cycle compression Electricity (Motor) or Fuel (Heat Engine) Heat-activated (Type 1) Heat-activated (Type 2) MVR TVR Fuel (Process Heat or Steam) Waste heat Electricity (Motor) or Fuel (Heat Engine) Steam Pros Cons Typical COP Good COP for moderate lift temperature Multiple vendors Electricity only on site - Requires low electric-fuel price ratio - Limited supply temperature to ~320F supply 3 to 10 - Uses lower cost fuel as driver Minimal moving parts Higher supply temperature ~400F - High CapEx Limited vendors Emerging technology 1.6 - Uses free waste heat as driver Minimal moving parts Higher supply temperature ~400F - High CapEx Limited vendors Emerging technology Requires cold sink T 0.5 - Good COP for moderate lift temperature Electricity only on site - 3 to 10 - Requires low electric-fuel price ratio High speed compressor - Low CapEx Simple and low maintenance - Low energy efficiency 2.0 ∆

An Untapped US Industrial Process Energy Efficiency Opportunity

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