A Perspective on Heating Technology Heat driven heat pumps – the future of domestic heating? Bob Critoph Director, i-STUTE University of Warwick R.E.Critoph@warwick.ac.uk UKLPG Annual Conference 6th October 2014
• Context • Introduction to technologies • Market potential in the short term • Barriers to development • Market potential in the longer term
Context • The UK is committed to a reduction in greenhouse gas emissions of 80% by 2050 across all sectors The Carbon Plan: Delivering our low carbon future. Presented to Parliament pursuant to Sections 12 and 14 of the Climate Change Act 2008 Amended 2nd December 2011
Context • The UK is committed to a reduction in greenhouse gas emissions of 80% by 2050 across all sectors Building a low-carbon economy – The UK’s contribution to tackling climate change. The First Report of the Committee on Climate Change December 2008 London: TSO . ISBN 9780117039292
Context • In 2011, RCUK initiated a call to fund up to six interdisciplinary Centres in ‘ End Use Energy Demand’. Each Centre would be funded for five years initially with a nominal budget of £5M. • i-STUTE was awarded one of the centres and funding commenced from April 2013 – its distinctive feature is concentration on heating and cooling.
Why heating and cooling? • 47% of fossil fuels in the UK are burnt for low Energy Consumption by end use 2012 temperature heating purposes (25% of CO 2 Other emissions) 14% • 16% of electricity in the Heat 47% UK used to provide Transport cooling - Worldwide it 39% represents 10% of greenhouse gas Provisional data for 2012 emissions (DECC)
Energy Consumption by end Heat Use by Sector use 2012 i-STUTE coverage in red Other 14% Industry 24% Heat 47% Domestic Transport Service 57% 39% 19% Provisional data for 2012 (DECC)
Bioenergy & Heat use by purpose Waste Heat sold 2% Low 2% temperature Drying/seperatio process Electricity n 9% 15% High 3% temperature process solid fuel 6% 3% Oil 7% Cooking/caterin g 5% Space Gas Water heating heating 71% 14% 63% Breakdown by fuel of total heat use i-STUTE coverage in red The largest component is in space and water heating – What do we plan to do about it?
Projects in Space Heating Task Compact chemical heat store Compact latent heat energy storage Advanced electric heat pump Next generation gas powered heat pump Heat emitter study
Projects in Space Heating Task Compact chemical heat store Compact latent heat energy storage Advanced electric heat pump Next generation gas powered heat pump Heat emitter study
Limitations of the energy infrastructure – why the future will not be renewable electricity and electric heat pumps. 2010 UK heat & electricity hourly demand variability Design point for heat delivery system Peak electricity demand will exceed electrical grid capacity in future ?? Design point for electricity delivery system Source: Energy Technologies Institute, 2012
• Domestic Heat pumps cannot economically provide the high powers (25kW) required for instantaneous hot water production • Grid limitations prevent even close to 100% of instantaneous demand heat pumps. 4 – 7 x Electricity distribution network In excess of 3 times the peak capacity needed? capacity needed? Rewire +250,000km in 15-30 years? GWh/d 35-40million heat pumps? 4500 1 in 20 Peak Network Electricity (with Fast Charge) 4000 20000 3500 18000 16000 3000 Consumption (kWh/6min) 14000 Other 2500 12000 2010 Air/Ground heat 2000 10000 2050_GG 2050_ER Heat Pump 8000 1500 100 GWe 100 GWe Electric load 6000 Power 1000 4000 2000 500 0 00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0 180 360 Time of Day Days Source: S. Marland, National grid, Why hybrids and gas heat pumps?, Source: S. Marland, National grid, Why hybrids and gas heat pumps?, GasTech seminar 19 th March 2012 GasTech seminar 19 th March 2012
What ways are there of addressing the problem?
1) Hybrids • Hybrid electric heat pump/gas boilers have been suggested as one solution but as the housing stock thermal performance improves, DHW provision will become a larger fraction of the total load. Source: E. Sutherland, Bosch, Bosch Hybrid, GasTech seminar 19 th March 2012
1) Hybrids • Hybrid electric heat pump/gas boilers have been suggested as one solution but as the housing stock thermal performance improves, DHW provision will become a larger fraction of the total load. Gas Condensing 3kw Air to Combi Boiler Water Heat Pump Source: Cliff Jones, Itho UK, GasTech seminar 19 th March 2012
2. Compact chemical/latent heat store • Another approach to the problem – heat storage Advanced compact heat stores can smooth out the diurnal peaks on the grid. They are part of a complex solution that involves hybrids, gas fired heat pumps and perhaps other technologies. Latent heat energy storage (short term) Chemical heat store (long term) • • Objective is to develop a POC chemical A nearer to market interim solution to the challenge thermal energy storage and delivery system with an energy density of at least • A phase change latent heat energy five times that of a comparable water storage approach. Energy density is store able to deliver all of its heat at a several times greater than water but temperature of 65˚C. subject to parasitic heat loss over time. • Challenges are materials selection, • This project will develop and test a reactor and system design, instantaneous prototype system scalable to meet 2-4 effectiveness, long term system hours of maximum winter space and performance. water heating load. Good for trimming peak loads over a day, important but not enough!
3. Gas heat pumps • Another option is the gas fired heat pump – three domestic, many commercial products on or near market:
Introduction to technologies Technologies • Engines
Introduction to technologies
Introduction to technologies
Introduction to technologies Technologies • Engines • Sorption Absorption Adsorption
Introduction to technologies Absorption Adsorption Performance similar in principle Refrigerants similar: • Water • Ammonia • Methanol
Introduction to technologies Absorption Adsorption How do they work???
Introduction to technologies Electric heat pump Heat to radiators 3 kW Electrically High pressure gas Liquid 1 kW driven (e) compressor Low pressure gas Heat from 2 kW outside air Heat out . COP ≡ = 3 Electricity in
Introduction to technologies Electric heat pump Heat to radiators 3 kW High pressure gas Liquid 1 kW Motor Compressor (e) Low pressure gas Heat from 2 kW outside air Heat out . COP ≡ = 3 Electricity in
Introduction to technologies 0.6 + 0.9 = 1.5 kW Gas engine heat pump Heat to radiators 0.9 kW High pressure gas Liquid 1 kW Gas Compressor gas engine Low pressure 0.3 gas kW work Heat from 0.6 outside air Heat out . kW COP ≡ = 1.5 Heat (gas) in
Introduction to technologies Gas engine heat pump Heat out . COP ≡ = 1.5 Heat (gas) in • Wins on fuel cost • Wins on CO 2 emissions • Maintenance, noise etc rule out domestic applications
Introduction to technologies 1.3 kW Absorption heat pump 4) Heat solution to 1 kW Heat to drive out gas at radiators gas high pressure 5) Gas condenses to liquid at high High pressure 3) Pump pressure gas Liquid ammonia solution to high pressure Low pressure 1) Low gas pressure ammonia liquid boils in evaporator 2) Low pressure Heat from 0.3 ammonia gas outside air Heat out . kW dissolves in COP ≡ = 1.3 Heat (gas) in water
Introduction to technologies 1.3 kW Absorption heat pump 4) Heat solution to 1 kW Heat to drive out gas at radiators gas high pressure 5) Gas condenses to liquid at high High pressure 6) Weak solution pressure gas Liquid throttled back to low pressure to absorb more gas Low pressure 1) Low gas pressure ammonia liquid boils in evaporator 2) Low pressure Heat from 0.3 ammonia gas outside air Heat out . kW dissolves in COP ≡ = 1.3 Heat (gas) in water
Introduction to technologies 1.3 kW Absorption heat pump Heat to radiators 1 kW gas High WHAT IS IN pressure gas Liquid THE BOX IS A HEAT DRIVEN Low pressure COMPRESSOR gas Heat from 0.3 outside air Heat out . kW COP ≡ = 1.3 Heat (gas) in
Introduction to technologies Adsorption heat pump
Introduction to technologies Adsorption heat pump 170º C Initial State: Pressure Ambient Temperature 40º C 40º C Low pressure High concentration 0º C
Introduction to technologies Adsorption heat pump 170º C Process 1 Pressure Carbon bed is heated, ammonia is 40º C driven off and 40º C pressure increases until… 0º C Heat Input
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