Energy Storage Technology Comparison From a Swedish perspective Felix Söderström Bachelor of Science Thesis KTH School of Industrial Engineering and Management Energy Technology EGI-2016 SE-100 44 STOCKHOLM Bachelor of Science Thesis EGI-2016 Energy Storage Technology Comparison From a Swedish perspective Felix Söderström Approved Examiner Supervisor Viktoria Martin Justin Chiu Saman Nimali Gunasekara ABSTRACT Due to increased usage of renewable energy sources a need to store energy, from times of low demand or high production to times of higher demand or lower production, have risen. This report is meant to serve as a comparison between different methods of energy storage from a Swedish point of view. Several technical aspects as well as environmental and social impacts of different energy storage methods have been compared. The conclusion reached is that PHES is still the most favourable way of storing energy due to the good performance and reliability it offers. If found possible, Sweden should therefore continuously expand the usage of PHES as well as continuing to improve the turbine efficiency. If further expansion of PHES is not possible, CAES could serve as a replacement due to similar performance. For storing energy during shorter periods of time, Li-Ion batteries or Na-S batteries are the most viable options. High efficiency and energy density as well as low costs are all desired characteristics. In most regards, Li-Ion batteries outperforms Na-S. Li-Ion should therefore be considered the primary way to store energy for shorter times in Sweden, despite Li-Ion’s slightly larger environmental impact. 1 SAMMANFATTNING På grund av en ökad användning av förnyelsebara energikällor har även behovet av att kunna lagra energi från tillfällen då mycket energi genereras eller efterfrågan är låg, för att sedan kunna använda energin då efterfrågan är högre, ökat markant. Den här rapporten är menad att jämföra olika metoder av energilagring ur ett svenskt perspektiv. Flera tekniska aspekter samt miljömässiga och sociala påverkningar hos flera energilagringsmetoder har jämförts. Slutsatsen som nåtts är att PHES ännu är den mest gynnsamma metoden att lagra energi baserat på dess goda prestationer samt dess pålitlighet. I den mån det är möjligt bör Sverige därför fortsatt försöka expander PHES samt fortsatt arbeta med att förbättra turbineffektivitet. Om vidare expansion ej är möjligt längre är möjligt kan CAES användas för långvarig energilagring på grund av dess liknande egenskaper. För kortvarigare lagring är Li-Ion eller Na-S de mest gångbara alternativen. God effektivitet och hög energidensitet samt låg kostnad är alla åtråvärda egenskaper. I de flesta av dessa aspekter presterar Li-Ion batterier bättre än Na-S. Li-Ion bör därför vara det primära sättet att lagra energi kortvarigt i Sverige, trots dess något större miljöpåverkan. NOMENCLATURE AC – Alternating Current PHES – Pumped Hydro Energy Storage CAES – Compressed Air Energy System SHS – Sensible Heat Storage DC – Direct Current SMES – Superconducting Magnetic Energy Storage FES – Flywheel Energy Storage TCS – Thermochemical Storage LHS – Latent Heat Storage TES – Thermal Energy Storage Li-Ion – Lithium-Ion UPS – Uninterrupted Power Supply Na-S – Sodium-Sulphur 2 TABLE OF CONTENTS 1 INTRODUCTION ........................................................................................................................................ 4 1.1 PURPOSE & DELIMITATIONS ................................................................................................................... 4 1.2 METHODOLOGY ...................................................................................................................................... 4 2 ENERGY STORAGE METHODS ............................................................................................................. 5 2.1 MECHANICAL ......................................................................................................................................... 5 2.1.1 Compressed Air Energy Storage (CAES) .......................................................................................... 5 2.1.2 Flywheel Energy Storage (FES) ........................................................................................................ 6 2.1.3 Pumped Hydro Energy Storage (PHES) ........................................................................................... 8 2.2 ELECTRICAL ........................................................................................................................................... 9 2.2.1 Superconducting Magnetic Energy Storage (SMES) ......................................................................... 9 2.3 ELECTROCHEMICAL .............................................................................................................................. 10 2.3.1 Supercapacitors ............................................................................................................................... 10 2.3.2 Battery Storage Technologies ......................................................................................................... 11 2.4 CHEMICAL ............................................................................................................................................ 17 2.4.1 Power-to-Gas .................................................................................................................................. 17 2.5 THERMAL ............................................................................................................................................. 18 2.5.1 Sensible Heat Storage (SHS) ........................................................................................................... 18 2.5.2 Latent Heat Storage (LHS) .............................................................................................................. 19 2.5.3 Thermo-Chemical Storage (TCS) .................................................................................................... 20 3 COMPARISON .......................................................................................................................................... 22 3.1 DISCUSSION .......................................................................................................................................... 24 3.1.1 Technical aspects ............................................................................................................................ 24 3.1.2 Environmental impact ..................................................................................................................... 25 3.1.3 Social impact ................................................................................................................................... 25 3.1.4 Technology maturity ........................................................................................................................ 27 3.1.5 Need and availability ...................................................................................................................... 28 3.2 CASE STUDY – WIND FARM AT BIOTESTSJÖN ....................................................................................... 29 3.2.1 Approach ......................................................................................................................................... 30 3.2.2 Case study conclusion ..................................................................................................................... 31 4 CONCLUSION ........................................................................................................................................... 32 4.1 FUTURE WORK ..................................................................................................................................... 32 5 ACKNOWLEDGEMENTS ....................................................................................................................... 33 6 REFERENCES ........................................................................................................................................... 34 3 1 INTRODUCTION Renewable sources of energy are becoming responsible for a larger share of electricity produced all over the world. Since it is not possible to regulate when and how much electricity that is generated from sources such as solar and wind power, a way to store the excess energy from times of lower demand or higher production is needed. During the last century several methods have been developed, ranging from the enormous water reservoirs of the pumped hydro energy storage (PHES) to the modern and theoretically optimal superconducting magnetic energy storage. Since applications and conditions vary between techniques, a comparison is necessary to evaluate what type of energy storage is needed. Comparisons have been done before, the intention with this bachelor of science thesis report however, is to have evaluated the results from a “Swedish point of view”. 1.1 PURPOSE & DELIMITATIONS This thesis has focused on energy storage from a “Swedish point of view”. General properties such as life time, efficiency, capacity, power, energy density and response time is regarded, as are costs, environmental and sustainability aspects, social effects and geographical requirements. The targeted technologies are those that are ready for the market today or in the near future. The aim for this paper is to end in a comprehensive comparison containing necessary information and a recommendation