2012 Energy Storage Symposium

Transcription

1 2012 Energy Storage Symposium Tim Fox Institution of Mechanical Engineers Storing Electricity Using Cryogenic Technology in a UK Policy Context

2 Storing Electricity Using Cryogenic Technology in a UK Policy Context Dr Tim Fox CEng FIMechE CEnv Head of Energy and Environment Institution of Mechanical Engineers

3 Introduction Overview Policy landscape and drivers A novel cryogenic approach Pilot plant project Barriers Policy needs Conclusions

4 Policy drivers Policy landscape EU Renewable Energy Directive (2009) Climate Change Act 2008 Policy mechanisms in play Renewables Obligation Banding Review Electricity Market Reform (EMR)

5 Storage enabling technology Intermittent renewable energy sources Wrong time electricity generation too much or too little Optimises return on investment (ROI) in renewables plant Reduces need for idle spare capacity (reduces investment costs in asset base) and avoids (volatile) fuel costs Large base-load electricity generation Sweats assets for improved ROI e.g nuclear and biomass Flexibility of scale and location Mix of storage technologies analogous to generation mix Defers network investments and lowers system costs Reduces SMART grid and interconnection risks

6 Principles Using cryogenic technology Use liquefied air or liquid nitrogen as storage medium Mature technology from air separation industry Proven standard equipment in daily use with well established supply chains Energy density of cryogen compares well with other medium

7 The Company Highview Power Storage Ltd Established 2005 to design and develop utility-scale energy storage and power systems 16 UK staff based London and Slough $18m equity investment plus $1.8m DECC capital grant Pilot Plant 300kW hosted by SSE at Slough Heat & Power Operating since April 2010, fully integrated into local distribution network Tim Fox thanks the Directors of Highview Power for permission to present this work at the Symposium and the engineering staff for assistance in preparing this talk.

8 The storage cycle

9 Value of cold recycle Available enthalpy for cold cycle ~300kJ/kg of liquid product Cycle simulation indicates near term target thermal storage efficiency of 80% would deliver >50% cycle efficiency Achieved on pilot plant Target cold recycle at full scale

10 TS diagram for power recovery Heat addition at Constant pressure Four Stage Expansion With re heat between stages Compression of cryogenic liquid

11 The value of waste heat More work recovered with use of waste heat

12 TS diagram for the complete cycle

13 Milestones The plant (1) 2005 research begins University of Leeds 2008 pilot plant project starts November Power recovery and cold recovery ops Spring STOR service trials begins Cold storage, recycle and liquefaction ops Spring Triad service trials 2012 pilot successful next step commercialisation Characteristics 300 kw turbine output, 20 (68 ) to 60 C (140 F) inlet temp 30 tonne/day liquefier, 2.5 MWhrs storage Note: STOR = Short Term Operating Reserve balancing duty

14 The plant (2)

15 Commercial Service Trials (1) Summary of STOR trials Over 2 week period achieved 94.6% availability.

16 Commercial Service Trials (2) Summary of US regional transmission operators (PJM) regulated service trial Success level of 99% against a pass mark of 75%

17 Results Power recovery Power (kw) Time (minutes)

18 Results Value of waste heat Due to the low bottom temperature of the cycle, the ideal (Carnot) efficiency of the CES cycle is high (c. 70%) even though the temperature difference is quite low (415 o F) The cycle is therefore very effective at converting low grade waste heat to power typically 56% of supplied heat is converted back to power, compared to 10 to 20% for a conventional Rankine cycle at commercial scale Comparison of ideal Carnot efficiency CES at Ambient 72% CES at 100 o C 80% Rankine Cycle at 100 o C 25% Super Critical Steam Cycle c. 70%

19 Results Cold recycle

20 Overall Pilot outcome Highview have successfully demonstrated use of cryogenic technology for electricity storage at pilot plant scale Viability of cold recycle to improve efficiency of cryogen manufacture Use of waste heat for cycle efficiency improvements Ability to deliver commercial reserve services

21 Possible next steps Commercial scale demonstration 10 MW output with >50% efficiency Liquefier sized to suit market application 100 s MWs output with GWhs storage Capital cost ~$900 to $1900/kW Annual O&M cost ~2% capital cost No geographical constraint and benign environmentally 70% efficient with waste heat at 239 F

22 Storage comparisons

23 Barriers and challenges Classification of storage solutions Electricity consumer and electricity generator Electricity market structure Competitive generation market and highly regulated transmission and distribution provider Need to be allowed to access multiple income streams Lack of incentivisation Research, development and demonstration funding UK National Grid estimates will need 4.5 GW of storage potentially have to import substantial amount of technology

24 Policy needs Recognise the value of storage Strongly dependent on network generating mix and local market rules Separate classification for storage Recognise unique roll as both consumer and provider Create competitive incentivised environment Needs to ensure inclusion and access to multiple streams Support demonstration at commercial scale

25 UK policy conclusions Support action to identify true system benefit of electricity storage Develop policy frameworks that reward value of electricity storage in UK power markets Encourage/support UK companies and research organisations that are developing storage technologies

26 Thank you Questions and discussion

27 2012 Energy Storage Symposium Wednesday, May 2 Thursday, May 3, 2012 Columbia University