Characteristics and Demands

Metrication

In the previous chapter various energy storage technologies and applications have been presented. In the following chapter these will be tied together as energy storage technologies will be evaluated for different applications.

3.1 Characteristics and Demands

Not all energy storage technologies can be used for all applications described in the previous chapter. Each application has certain requirements that an energy storage technology needs to fulfil to be suitable. These requirements are shown in table 3.1. Parameters of importance are for example the response time and the storage duration, as the storage system needs to be able to respond within a certain time to be useful and has to be able to store energy over the required amount of time for an application. An energy storage system that can only store energy for hours cannot be used as seasonal storage, where energy storage for months is needed. Some of the capabilities of the energy storage technologies mentioned in chapter 2 are listed in table 3.2.

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EnergyStorageApplications PowerRequirements StorageTime ResponseTime DischargeTimeOther SuitedTechnology

EnergyArbitrage≤500𝑀𝑊h-Days-≤10ℎ RequiresHighEfficiency Li-ion,PHESCAES

PeakShaving2MW/<1MW1-10h/ca.1h<1MinMin-h- Li-ion,FuelCellPHES,CAES

LoadFollowing1-100MWMin-h<1s15Min-1h- Li-ion,FuelCellFlywheels

BlackStart5-50MW-≤2ℎ15Min-1h RequiresESStobeIndependentofGrid Li-ion,FuelCellPHES,CAES

SpinningReserve10-100MW≤30𝑀𝑖𝑛s-Min15Min-1h-Li-ion,FuelCell

FrequencyRegulation≤100𝑀𝑊- Instantaneous-Min≤1ℎ- FuelCellHCE

VoltageSupport1-10MVAR-<100ms1s-1Min- Li-ion,FuelCellFlywheels

PowerQuality 1-4MW/100kW-10MWs<200ms10s-15Min- Li-ion,FuelCellHCE,Flywheels

PowerReliability<10MW-Min≤4ℎ- Li-ion,FuelCellCAES,PHESFlywheels RenewableCapacityFirming<500MW-<30Min≤4ℎ- Li-ion,FuelCellPHES,CAES

RenewableEnergyTimeShift<500MW-<30Min≤5ℎ- Li-ion,FuelCellPHES,CAES

SeasonalStorage >1MW/50-300MWWeeksMin-- FuelCell,HCE?PHES,CAES

Table3.1:EnergyStorageApplicationRequirements[47][78][85][86][87][88][89]

3 . 1 c h a r ac t e r i s t i c s a n d d e m a n d s 31

EnergyStorage Technology Roundtrip Efficiency Power Rating Discharge Time Self-Discharge PerDay Storage Duration Response Time FullCycle Life CAPEX ($/kW) Li-ion95%/>90%

0-100kW 100MWMin-h/s-h0.1-0.3%Min-Days<1s1000-100001200-4000 FuelCells<59%/<50%

200kW 0-50MWs-h

Almost Zeroh-Months≤1𝑠1000+

500/10000+ 3000-4500(fuelcellsonly) HCE<44%1-2MW---s-300 PHES87%/ca.75%

4000MW 100-5000MW1-24h Very Small ca.12h h-MonthsMin-

h-MonthsMin-600 600-2000 CAES<50%-70%

50-220MW 5-300MW1-24h+Small h-Days h-Monthss-Min- h-Monthss-Min-425-517 400-800 Flywheels90-93%/90-95%

750kW-1650kW 0-250kWms-15Min100%-<1s20000+

300-350 250-350 Table3.2:CharacteristicsofEnergyStorageTechnologies[47][58][59]

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To get an overview over which energy storage technology can be used for certain applications a grading scheme has been developed to rank the systems according to their applicability. The grading scheme considers requirements such as the initial cost associated with an energy storage technology (CAPEX), the need for specific geographic locations such as caverns or basins, and general applicability. The general applicability considers whether an energy storage technology meets the requirements of a given application.

To each of the requirements mentioned a maximum set of points are given.

Geographic requirements are classified into three main categories, INSIGNIF-ICANT, NORMAL, and HIGH, associated with 9, 5 and 2 points, respectively.

Insignificant means that the energy storage technology does not require any special geographic conditions other than perhaps a flat surface to be imple-mented. NORMAL indicates that some geographic requirements need to be met, such as access to the sea, as can be the case for CAES. High geographic requirements express the need for specific geographic locations for the energy storage technology to be used. Additionally, this score is multiplied by 0.7.

Any storage technology can get a maximum score of 6 points in the CAPEX category, with the least expensive technologies getting the maximum score and the next cheapest getting 5 points and so on. Points are not awarded if the technology does not fulfil the general applicability, meaning that it is not applicable for the specific application considered. In addition, the score in this category is multiplied by a factor of 0.3.

The above-mentioned scores are then multiplied with each other and then multiplied by either a 1, if the technology fulfils the general applicability cat-egory, or by 0, if the energy storage technology does not fulfil this category.

Thus, the maximum score to be gained overall is 11.34, while the lowest score is 0 points. The higher the score the better. Considering the maximum amount of points awarded in each category and the additional weights by which they are multiplied, the category weighted the most is the geographic demands category.

This is because not all locations for which energy storage is required necessarily have the right geography, thus making certain energy storage technologies less universally applicable. Ideally, an energy storage technology is applicable in as many locations and scenarios as possible.

The scores of the technologies presented in chapter 2 are listed in table 3.3, and as the grading scheme is based on points, the numbers presented are dimensionless. Furthermore, the points given to the energy storage technolo-gies in each category and for each application can be seen in table a in the appendix.

3 . 1 c h a r ac t e r i s t i c s a n d d e m a n d s 33

Energy Storage Applications

Li-Ion Fuel Cell HCE PHES CAES Flywheels Energy Arbitrage 9._{45 0}._{00 0}._{00 2}._{52 6}._{3 0}.₀₀

Table 3.3:Rating Energy Storage Technologies for Energy Storage Applications As illustrated by the scores in table 3.3, the lithium ion batteries and fuel cells are applicable for most applications and they outscore the other technologies mainly because they are less limited by geography and thus more universally applicable and attractive.

Table 3.3 also shows that lithium ion batteries generally outperform fuel cells except when it comes to long term/seasonal storage. A hybrid system based on both fuel cell and lithium ion battery can be assumed to work best in a situation where fuel cells and hydrogen storage take care of the long term energy storage, while lithium ion batteries are used for energy storage on shorter time scales.

With regards to seasonal storage a Hydrogen Combustion Engine would be preferable over fuel cells, however, due to the lack of data on fuel use, fuel cells are considered from here on forward.

In the following chapters two scenarios are considered. One of these requires long term energy storage, in the form of seasonal storage and short-term energy storage, for renewable energy time shift. The other requires energy storage for the short term.

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