HIGHVIEW POWER STORAGE TECHNOLOGY AND PERFORMANCE REVIEW

Transcription

1 HIGHVIEW POWER STORAGE TECHNOLOGY AND PERFORMANCE REVIEW MARCH 2012

2 1 HIGHVIEW S TECHNOLOGY Although novel at a system level, the components and sub- systems of Highview s process utilise mature technology that can be readily sourced from large OEMs. The technology draws heavily on established processes from the turbo- machinery, power generation and industrial gas sectors. Highview expects this to provide a shorter product validation period and lower technology risk than most new technologies being introduced in the clean tech and energy storage space. The thermodynamics of the cycle used for Highview s technology and the ability to assemble the units from well proven, mature components lead to several features which the company believes make it attractive compared to alternatives. In common with all energy storage systems, the Highview technology comprises three components: a charging system; an energy store; and a discharging (or energy recovery) system. The combination of all three sections of the process forms Highview s proprietary re- chargeable liquid air energy storage system and is known as a Cryo Energy System. 1.1 Charging System The charging system of Highview s technology comprises a liquefaction plant which, by utilising a compressor driven, Claude cycle based refrigeration cycle (much like that employed in a domestic refrigerator), uses electrical energy to reject heat from process air drawn from the environment and generate liquid air. This is a mature process which can be carried out on a large scale utilising equipment widely deployed in the industrial gas industry. 1.2 Energy Store The liquid air is stored in an insulated tank at low pressure 1, which functions as the energy store. This equipment is widely deployed as bulk storage of liquid nitrogen, oxygen, LNG or argon at the scale required for Highview s technology. 1 Cryogenic tanks are typically held at <10 bar at the 100 ton scale and at atmospheric pressure at the ~1,000 ton and above scale

3 Cryogenic vessels at a Linde large scale liquefaction facility 1.3 Power Recovery When power is required, liquid air is drawn from the tank and pumped to high pressure. Ambient (or higher temperature waste) heat is applied to the cryogen via heat exchangers (and an intermediate heat transfer fluid usually a water/glycol mix) which results in the cryogen changing into a high pressure gas which is then used to drive a turbine and generator. The turbine exhaust gas is recycled as part of the process and its residual heat removed to help drive the evaporation of the cryogen. This produces a very cold gas stream, the cold content of which is stored in a proprietary high- grade cold store and then used later to enhance the efficiency of the liquefaction plant at the heart of the charging process. The use of above ambient temperature heat (including low grade heat) to drive the power recovery process generates additional power which, assuming the heat has no economic cost to the process, improves the overall round trip efficiency of the cycle 2. 2 The ideal Carnot cycle efficiency is limited by the highest and lowest temperatures. Raising the higher temperature with waste heat increases the work available

4 In addition, the wide temperature ratio of the extremes of the cycle temperatures used in Highview s system gives rise to a very efficient conversion of heat into power (in the 50-60% range at commercial scale see below for Pilot Plant heat to power performance data). The Highview Pilot Plant. The tank is the energy store containing cryogen and the shipping container on the left houses the power recovery turbine, with the cold store sitting on top of it. The structure behind the cryo- tank is the liquefaction unit.

5 Schematic diagram of the Cryo Energy System (copyright: Highview Power Storage) 1.4 Development Timeline Highview s path to commercialisation began in 2005 when the Company s founders began working with scientists from the University of Leeds to examine the potential of and begin developing a large- scale energy storage system using cryogen.

6 1.4.1 Cold Recycle Proof of Concept (2007) After two years of research and development, a kilowatt scale unit with an operating time of four hours was built and tested to validate the cold recycle concept. It was hosted at the workshops of a leading cryogenic installation contractor (AES Engineering in Manchester). The demonstration system operated at 100 barg pressure and successfully proved that cold recycling could be incorporated as part of a Cryo Energy System Power Recovery Proof of Concept (2008) A lab- scale power recovery system with a capacity of about 5kW and a working time of four hours was designed and built at the Company s R&D facility. The system was conceived to demonstrate the proof of concept of the power recovery system and integrate it with the cold recycling plant. The test rig proved successful on both counts, with the experimental results showing a strong correlation with simulations, indicating a very good understanding of the cycle behaviour. The technology development progress over time is shown in the chart below. Technology development and path to commercialisation 2 THE PILOT PLANT Having successfully demonstrated the technology at lab scale, Highview raised the necessary capital to build a Pilot Plant on a scale approximately 60 times larger than the lab scale unit which would demonstrate the way the technology would scale to a size suitable for utility applications. The Pilot Plant was commissioned in July 2011 and is presently demonstrating the proprietary cycle at a significant scale (currently operating at around 300kW maximum output) as well as validating the integration of all key sub- systems and components, including safety controls. It is also providing valuable operating data which will allow Highview to match performance against its simulation for the whole system, providing useful design validation for the next, larger commercial- scale units. The Pilot Plant also allows the Company to validate and optimise the cold recovery cycle under constant and intermittent operation. Locating the project on Scottish and Southern Energy s ( SSE ) Slough Heat & Power site has given the Pilot Plant access to a heat- stream from a local biomass power station, thereby providing the opportunity to measure the relationship between power output and turbine inlet temperature when

7 utilising a waste heat stream (up to 60 0 C), illustrating the ability of the system to extract work from waste heat. The drawing below shows the Pilot Plant, including the liquefier and all balance of plant items Cryogen storage 2. Power recovery (40 ft container) 3. High grade cold store 4. Cold circulation compressor 5. Recycle compressor 6. Main compressor 7. Air purification unit 8. Main cold box

8 The Pilot Plant top level process flow diagram is shown below. Air Regen 1 9 MAC Exhaust Cold Box HX 12 High Grade Cold Store RAC 8 23 Air Purification Unit 10 4 Turbine Expander 7 Phase Separator Tank Cryo Pump Subcooler Evaporator Stage2-3 Re Heater 18 Tur 17 Stage1-2 Re Heater Super Heater Turbine Stage 2 Turbine Stage 1 Stage Re Heater Turbine Stage 3 Turbine Stage 4

9 Internal view of power container for the Pilot Plant, showing the power turbine Internal view of the power container showing the heat exchanger array

10 Total project costs and cost breakdown of the Pilot Plant are set out in the table below. Component Cost Percentage of total Turbine 631,264 19% Heat Exchangers 87,058 3% Cryo- pumps 74,304 2% Generator 17,100 1% Balance of Plant 480,735 15% Commissioning 44,768 1% Sub Total (Phase 1) 1,335,229 41% Compressors 459,528 14% Liquefier 741,821 23% Glycol System 26,580 1% Cold Storage 116,146 4% Mechanical Works 209,268 6% Electrical Works 244,812 8% Site Works and Commissioning 120,154 4% Sub Total (Phase 2) 1,918,307 59% Grand Total 3,253, % Note: The liquid air storage tank is secured on a lease basis from BOC/Linde 2.1 Pilot Plant Performance The Pilot Plant was initially commissioned in April 2010 as a storage tank and power turbine only, without the ability to charge itself (the charge coming from tanker deliveries of liquid nitrogen). Early in 2011 construction work began on the liquefier which once commissioned (in July 2011) provided the on- site charging capability. As is normal practice for a Pilot Plant, the plant was heavily instrumented to facilitate the capture of as much useful information as possible from its operation which could be used to direct design improvements to this and future units. The Company s view of the unit post commissioning is one of high reliability and availability which responded to control inputs readily; had very few trips; and provided a stable output.

11 The table below provides an overview of the Pilot Plant activity as at 1 March Parameter Outcome Notes Total Operating Hours: Power Turbine Liquefier 125 hours 281 hours 2 years equivalent operation as a reserve plant, includes over 100 starts Number of Starts 103 Total Mass of Cryogen Processed ~829,000 kg Maximum Power Output ~356 kwe (at the generator) With 60C heat Storage capacity 8 hours operation 60 ton tank used equivalent to ~2.6MWh Maximum Pressure (power turbine) 60 bar System capable of 70 bar subject to turbine inlet nozzle adjustment Typical temp differential from 2 degrees Celsius Below 10C is indicative of cryogen inlet to exhaust gas good potential for cold recycle Percentage of available cold 99% >95% is required for good scavenged from evaporator cold recycle Trips or unplanned shutdowns in first three months of testing (system shakedown) Trips or unplanned shutdowns in subsequent four months of operation 22 High number of shut downs during initial testing while system was tuned 4 Good reliability (for a Pilot Plant) after initial shakedown Maximum production rate 1.44 tonnes per hour Slightly higher yield than design Specific work (without cold MWh per Tonne Approximately 6% better than recycle_) design Air cleaner performance <0.5 ppm H 2 O, <0.5 ppm CO 2 Maximum boost pressure 12 bara Larger systems would typically use a peak pressure in the bara region increasing efficiency Product delivery pressure 10 bara Suits small tank used at Pilot Plant

12 Principal Components Supplier Comments Main Air Compressor Atlas Copco Similar technology used in large scale units Recycle Air Compressor Atlas Copco Standard screw compressor used in the Pilot Plant. Centrifugal technology used at scale (Atlas Copco are also a supplier of such equipment) Cold Turbo-expander Inlet air cleaning skid Main cold box and associated heat exchangers Chengdu Air Chengdu Air Hanazhou Zongtai Process Equipment Co Supply several of the major gases companies use this supplier for large scale units Principal cryogenic and other critical valves Flow Serve Major international valve supplier used to ensure compliance with EU standards Control System Blackburn Starling Bespoke design for pilot plant but design conforms to industry best practice High Grade Cold Store Craufurd Engineering Bespoke design for pilot plant to test key aspects of concept Plant Pipework Atlas Engineering Services Local pipework and engineering contractor employed Power Turbine Concepts NREC Specialist turbine designer and one- off builder Generator ABB Standard 2 pole asynchronous air cooled machine High pressure cryogenic Heatric High pressure diffusion bonded device heat exchangers Pipework and containerised assembly Ross- shire engineering Specialist ME contractor and pipework fabricator Cryogenic feed pumps Cryostar Standard reciprocating pumps The operational testing of the Pilot Plant focused on four key areas: cold recycle, reliability, response and heat to power performance. The results of the tests carried out to date are summarised in the following sections.

13 2.1.1 Cold Recycle Besides providing a demonstration of the system on a practical scale, one of the main drivers for building the Pilot Plant was to prove and validate the effects of cold recycle (and hence round trip efficiency improvement) on a typical commercial liquefier design. The effect of cold recycle on the liquefier has been tested following its installation and commissioning in 2011 and the results are discussed below. The specific work required for the liquefier to generate liquid air under various levels of cold recycled from the High Grade Cold Store has been measured over many hours of operation and compared to both the predicted performance as well as the guarantee point supplied by the liquefier manufacturer. The chart below shows the results from a number of tests on the pilot plant. The gross specific work (kwh/kg) of producing liquid air was calculated from the main and recycle air compressor power consumption. This is plotted against the specific cold recycle enthalpy available at the test condition. The performance guarantee offered by Chengdu Air Separation (the supplier of the liquefaction plant) was based on gross power consumption hence the use of this measure (for all data shown in the chart) rather than the net power consumption. Tests were performed over a minimum of a one hour period to ensure the plant was stable. The actual test results fall on a line parallel with and within the supplier s guarantee line, and also agree closely with Highview s modelling (using Hysis) of the Pilot Plant. In particular, The Pilot Plant is observed to operate at a specific work approximately 0.15kWh/kg better than the guaranteed performance offered by the supplier without cold recycle. The absolute measured improvement with cold recycle matches closely the liquefier supplier s guaranteed improvement. The predicted performance from a Hysis process model of the Pilot Plant also is also shown on the figure. The predicted performance follows a parallel (and close) curve to the observed results, which indicates the validity of the process model.

14 Liquefier Specific Work, kwh/kg Pilot Measured (Mass Balance) Cheng- Du Guarantee Hysys Specific Cold Recycle, kj/kg Results from pilot plant steady state cold recycle performance tests - 158degC@0.4kg/ s Cold Recycle Flow - Cold Recycle Flow The results obtained from the Pilot Plant indicate (a) that cold recycle performs in line with expectations (b) the effect of cold recycle can be modelled using Hysis. The Company now plans to utilise the knowledge gained from these trials to incorporate a commercial sized liquefier operating with two expansion turbines and at higher pressures with the target level of cold recycle (~250kJ/kg of liquid air processed compared to ~160kJ/kg in the Pilot Plant) into the design for a commercial scale Cryo Energy System demonstration plant Reliability In order for Highview s technology to function as an economic proposition it must be able to deliver high levels of reliability. As part of its wider testing programme of the Pilot, Highview conducted a series of tests to examine the technology s ability to comply with the operational requirements of a National Grid Short Term Operating Reserve ( STOR ) contract as well as PJM s Regulation service. During the STOR contract trial, which lasted two weeks, the unit was held in a state of readiness for four hours per day and called into service at short notice. A reliability of 95% was

15 achieved. In the Company s view this is very high for a Pilot Plant and provides a high level of confidence that a commercial scale unit would meet the necessary level of availability and reliability to function as a STOR provider. PJM s regulation service involves running the plant with 10 minutes notice to a pre- agreed level and then following an automated signal which may call for a sudden increase or decrease in output. PJM publish a self testing protocol for the regulation service which Highview used to test the Pilot Plant. The resulting score was 99.8% compliant (compared to a pass mark of 75%) as reviewed by the PJM assessors. The diagram below shows the Pilot Plant performance compared to the control signal. Pilot plant response to the PJM regulation test protocol In addition, during the course of winter 2011/12, the Pilot Plant has been operated to try and meet the three periods of highest demand (also known as triads ) which determine the charging rates for use of system demand costs. The Pilot Plant site host (SSE) provided estimates of the triad time periods based on a high, medium and low probability of the period actually turning out to be a triad. The unit was operated for all high and medium triad warning periods without incident achieving 100% availability for the relevant time slots.

16 2.1.3 Response As well as examining reliability, the STOR tests also measured the time taken by the unit to reach a set load point. A 20- minute response time to reach the set point output from an instruction is generally considered to be acceptable for a STOR provider. In the case of the Highview Pilot Plant, the unit was able to reach the desired output in around 2½ minutes, making it a potential candidate in larger configurations for additional revenue from the fast reserve market as well as STOR. The Pilot Plant response from instruction is shown in the chart overleaf. 40 Start Up Test, 15 September Call Turbine Start (12sec) MCCB IN (111sec) 150Kw (155sec) Pressure (bar) Power (Kw) CV8 30% Pump speed increased to 30% PLC Opens CV8 to 60% SP Entered CV8 20% 5 CV8 10% Time (seconds) Stage 1 inlet Gen kw Heat to Power Performance One of the advantages of the power recovery cycle employed by Highview is its ability to efficiently capture low grade heat. The Pilot Plant has been configured to take advantage of heat supplied from SSE s system at Slough Heat and Power and as a result the power output at various temperatures has been mapped. This is shown in the diagram below.

17 Pilot Plant Power Recovery Module Turbine Inlet Temperature Swing at 48bar Turbine Inlet Pressure Generator Power, kw Turbine Inlet Temperature, degc Pilot Plant heat to power relationship. This is expected to improve significantly at commercial scale. As can be seen, at the operating conditions examined (48 bar inlet pressure) an increase of 1C results in an increase in output of 1kW. In terms of the overall use of external heat to generate power, the Pilot Plant is able to process 47% of the external heat applied into electrical power this high level of efficiency is attributed to the very wide temperature ratio over which the cycle operates. The Pilot Plant has been designed to demonstrate the entire Cryo Energy System cycle. Due to the small scale of this unit, when the cold recycle is operational the round trip efficiency is (by design) low in relation to what is obtained in commercial scale models - in the 7-12% range (see table below). Significantly, however, it does effectively demonstrate one of Highview s key pieces of intellectual property, which is the large reduction in liquefaction power requirement through cold recycle. The factors driving the Cryo Energy System s round trip efficiency are summarised in the table below, with the liquefier scale and cold recycle having a marked effect.

18 Pilot Plant (~30 tons per day and ~300kW output) Commercial Scale (>300 tons per day and ~10MW output) Liquefaction plant kwh/kg 0.4 kwh/kg After cold recycle via kwh/kg 0.2 kwh/kg High Grade Cold Store Cryo GenSet cryogen ~0.06 kwh/kg 0.12 kwh/kg usage Resultant round trip efficiency for Cryo Energy System 7-12% 60% As can be observed, the largest factor is the existing performance exhibited by large scale liquefaction units compared to the small scale unit procured for the Pilot Plant (0.4 kwh/kg compared to around 0.75 kwh/kg). The next most significant item is the effect of cold recycle, which is expected to roughly halve the energy cost of driving the liquefaction unit through the use of the high grade cold store in the cold recycle process. The ability of the power turbine system to convert cryogen to power is also relevant. The unit presently used in the Pilot Plant is capable of converting around 0.05 kwh/kg in its present configuration. Through the use of larger scale units and greater process pressure, the commercial demonstration plant (see below) is expected to achieve a performance of >0.1 kwh/kg (as outlined in the table above) hence allowing the overall Cryo Energy System unit to approach 60% round trip efficiency. A further factor influencing the overall efficiency of the Cryo Energy System is the cold store efficiency. A more efficient cold store permits greater cold recycling and hence lowers power consumption of the liquefier. The table below shows the effect of the high grade cold store thermal efficiency around a base case of 80% on the commercial scale mature overall system round trip efficiency of 60%. The larger systems are able to take advantage of larger more efficient liquefiers (hence the examination of a range of base line liquefier efficiency). Cold Store Efficiency Baseline Liquefier Efficiency 0.4 kwh/kg 0.43 kwh/kg 0.47 kwh/kg 88% 71.4% 65.7% 60.2% 80.0% 64.5% 60.0% 54.9% 72.0% 55.5% 51.8% 47.4% The effect of cold store thermal efficiency and baseline liquefier efficiency (without cold recycle) on overall round trip efficiency

19 3 INDICATIVE COMMERCIAL DEMONSTRATION PLANT DESIGN Following the successful construction, commissioning and operation of the Pilot Plant, the Company is developing a Commercial Demonstration Plant design. This unit will serve to demonstrate at commercial scale the ability of Highview s technology to provide relevant services to meet the existing and anticipated needs of the relevant market. It makes sense to develop plants that demonstrate Highview s breadth of market offering and also are relevant to the specific issues faced in the relevant markets. The two applications most suited to Highview s technology are reserve power and peaking power, and the Commercial Demonstration Plant project has been designed to demonstrate both these applications. 3.1 Configuration and budget The Commercial Demonstration Plant builds on the experience of the Pilot Plant and will likely comprise: A 10MW power recovery turbine unit with appropriate cryogenic feed pumps and storage tanks with around 40MWh of storage capacity; and One ~300 t/day liquefaction plant and a high grade cold store (making an integrated 10MW Cryo Energy System). In putting together the design brief for the this Plant, the Company has tried to adhere to a few key principles which are intended to ensure that the probability of delivering its desired growth is maximised while costs are minimised. These include: The use of off the shelf components to minimise non- recurring engineering content; Use of a simple, proven low cost turbine package; The use of waste heat to enhance performance; and The use of plant components at a scale which is beyond the necessary threshold to achieve commercially acceptable round trip efficiency (particularly relevant to the liquefier). Some of the principles result in performance limitations (see table below), but taken as a whole offer the prospect of an early market entry, with limited product development deferred to a period when the Company s position is more established.

20 Parameter Power turbine - Operating pressure Liquefier - Number of refrigeration expanders Selected Level for Pro Commercial Demonstration Plant ~100 barg Readily available technology at required flow levels Con Limits product efficiency 2 In line with commercial units Increases cost for unit Liquefier Capacity ~300 tonnes per day (tpd) In range for commercially acceptable efficiency At bottom end of acceptable efficiency (a larger unit would be more efficient) The level of design detail is sufficient at this stage to have sought levels of interest and budget quotations from the supply chain for the major components. Supply chain feedback indicates that the Commercial Demonstration Plant should be able to be completed at a price of around 2,200/kW which is compatible with the Company s expectations around cost versus maturity. Given the expected delivery periods for the long lead components (and assuming that lead times are not unduly extended), the unit should be operational approximately 24 months from notice to proceed).

21 The table below provides a breakdown of the indicative cost of the Commercial Demonstration Plant. ( 000) Cost Estimate LIQUEFIER Liquefier process equipment 1,140 Cold box assembly 370 Recycle compressor 920 Air compressor & dryer 700 Control & instrumentation 340 Electrical 270 Cooling water 120 Bulks 270 Engineering & site supervision 2,370 Construction 2,600 Miscellaneous costs 1,120 Cryo Tanks 900 Cold Storage 500 LIQUEFIER SUB TOTAL 11,620 POWER RECOVERY Turbines 4,173 Cryo Pumps 567 Control &instrumentation 450 Heat Exchangers 750 Pipework 1,000 Electrical 500 Miscellaneous Equipment 604 Construction 672 Engineering & Supervision 1,500 POWER RECOVERY SUB TOTAL 10,216 PROJECT TOTAL 21,836

22 The basic process flow diagram which describes the Commercial Demonstration Plant is shown below. The unit is designed around an expansion turbine which processes cryogen heated to around 200 o Celsius from a high grade waste heat source (such as the exhaust from a landfill gas engine) to attain the desired efficiency at low capital cost. Liquefier Process Flows for 10MW CES

23 Power Recovery Unit Process Flows for 10MW Cryo Energy System Tank 1 C o ld S to re re to S ld C o High Temperature Heating Loop Cryo Pump Super 2 Evaporator 3 Heater 4 Stage2-3 Re Heater 7 T u r 6 Stage1-2 Re Heater 5 Turbine Stage 2 Turbine Stage Stage 3-4 Re Heater Exhaust Turbine Stage 3 Turbine Stage 4

24 4 FUTURE PRODUCT DEVELOPMENT The design for the Commercial Demonstration Plant involves some compromises in order to get a low cost first- of- a- kind product into the market relatively cheaply and quickly, while at the same time demonstrating acceptable commercial round- trip efficiency. This last factor requires the Reference Plant to be located adjacent to a source of high grade heat, with the number of turbine stages and operating pressure also acting as limiting factors in terms of product efficiency and capital cost. It is important for Highview to keep developing product performance in order to reduce the reliance on co- locating Cryo Energy System plants with a high grade heat source to maintain efficiency. The Company plans to implement the steps set out below to deliver the appropriate improvements thereby reducing a potential location constraint. Once a large enough scale is reached, the three main drivers of efficiency for the system are: Re- heat and inlet gas temperature Number of power turbine stages Maximum operating pressure of the system. All these parameters contribute to and influence the quantity of cryogen which is required to generate a unit of electrical power output (measured in kwh output per kg of cryogen used). To achieve acceptable levels of performance (i.e. >50% round trip efficiency and competitive performance with OCGTs ) the Company believes that the power recovery process will need to deliver close to 0.1 kwh of power output per kg of cryogen removed from the store. The table below indicates the product development steps intended to achieve this aim. As indicated above (see Pilot Plant performance), further enhancement of the overall round trip efficiency may be achieved by improving the thermal efficiency of the High Grade Cold Store employed in the cold recycle system. 4.1 Basis for Cost Projections During Highview has obtained quotes from the supply chain for the major equipment items which would form a 10MW unit, namely: 300 tonnes per day (tpd) liquefier including all BOP items and construction costs (this is necessarily somewhat generic as some element of cost will be application and site specific); 3.5MW integrated turbine expander unit including generator and relevant BOP; Cryogenic feed pumps. The remaining BOP items such as tanks, heat exchangers, pipework etc., we have estimated based on our experience gained in building the pilot plant.

25 The 10MW unit (3x 3.5MW) is then used to scale all other systems in two dimensions scale, where a factor of 0.6 is used (meaning a 20MW unit would cost (20/10)^0.6 times as much as the 10MW unit volume, where a learning rate of 17.5% has been used, meaning that costs reduce by 17.5% every time the number of repeat units is doubled. While these factors are (of course) open to challenge, we have based our choices on general experience in the utility sector over many years (especially around the introduction and widespread deployment of CCGT plant) and in particular referred to material prepared for the UK government in examining the potential costs of carbon capture systems for utility plant. The tables below show how these two factors affect the costs of the major sub- systems (liquefaction, power recovery and tanks plus high grade cold store). Liquefier Input power (Liquefier size) 4MW (480 tonne/day) 20MW (2,400 tonne/day) 80MW (9,600 tonne/day) First of a Kind 10 th of a kind CAPEX as a CAPEX as a function CAPEX function of Power CAPEX of Power capacity capacity [ 000] [ /kw] [ 000] [ /kw] 13,506 3,377 7,129 1,782 35,475 1,774 18, ,500 1,019 43, Power Recovery System Turbine size (output power) [MW] First of a Kind 10 th of a kind CAPEX as a CAPEX as a function CAPEX function of Power CAPEX of Power capacity capacity [ 000] [ /kw] [ 000] [ /kw] 10 6, , , , , ,

26 Storage Tanks and High Grade Cold Store (no cost reduction for repeat build assumed) Tanks: cryo store + HGCS FOK ( 000) /kw/h 85.7 MWh (857 tonne) MWh (4,286 tonne) ,714MWh (17,143 tonne) These main subsystems may then be combined to form whole systems, with the tank size, liquefier capacity and generator/turbine size selected to suit the application. The limits of these combinations are shown in the two tables below. The first, illustrating a reserve application which due to lower utilisation can tolerate a smaller liquefaction plant. The second, illustrating a daily cycling plant, with the capability of fully recharging its storage tanks overnight and therefore requiring a proportionately larger liquefaction tank. Reserve Unit (1h/week) Daily Cycling Unit FoK CAPEX 10thoK CAPEX (4h/week) PRU Liquefaction Tank + HGCS [ 'm] [ /kw] [ /kw/h] [ 'm] [ /kw] [ /kw/h] 10MW 2.5MW (300 tonne/day) 10MWh (100 tonne) ,718 1, MW 2.5MW (300 tonne/day) 50MWh (500 tonne) MW 4MW (480 tonne/day) 200MWh (2000 tonne Daily Cycling Unit Daily Cycling Unit FoK CAPEX 10thoK CAPEX (4h/business day) PRU Liquefaction Tank + HGCS [ 'm] [ /kw] [ /kw/h] [ 'm] [ /kw] [ /kw/h] 10MW 4MW ( MWh tonne/day) (857 tonne) , , MW 200MW 20MW (2,400 tonne/day) 80MW (9,600 tonne/day) MWh (4,286 tonne) 1,714MWh (17,143 tonne) 62 1,

27 In the extreme, these configurations include some very large equipment (200MW range). Although the supply chain believes this to be well within range, the volume relationship (17.5% learning rate) is unlikely to be entirely robust at this scale due to the increasing level of on- site assembly required. The scaling factor is however, expected to remain robust. On the basis of this analysis we are confident that Highview s Liquid Air Energy Storage technology will achieve its capex target of per kilowatt.