The possible effects of pipe materials on drinking water quality have been analyzed in the distribution system of the water treatment plant of "La La Concepciónâ " in Tegucigalpa, Honduras. "La La Concepciónâ " is a surface water reservoir experiencing biogeochemical cycling of manganese. Black water problems have been reported in the distribution system since 1998. An evaluation of the potential influence that PVC and iron pipes could have on the concentration of iron and manganese in drinking water, the effects caused by the presence of manganese in PVC and iron pipe surfaces, and residual chlorine and Pb concentrations in the distribution system was performed. The sampled neighborhoods received an intermittent service. Water was suspended for 8 hours every day due to water quantity problems in the city. Water and pipe samples were obtained for PVC and galvanized iron pipes because these constitute the majority of the infrastructure used for distribution systems in Honduras. Thermodynamic and kinetic conditions for possible manganese oxidation by chlorine and dissolved oxygen in the distribution system were also evaluated. As expected, total Fe concentrations were greater for first flush conditions from the iron pipe. Water samples obtained from the PVC pipe showed higher total Mn concentrations and more black color than those obtained from the iron pipe for both first flush and continuous flow conditions. Residual chlorine decayed relatively fast along the sampled section of the distribution system. Pb concentrations were detected on water samples obtained from PVC for first flush and continuous flow and on iron pipe for first flush. Preliminary experiments showed that manganese-oxidizing and -reducing bacteria were present in the walls of both PVC and iron pipes. Higher numbers of colony-forming microorganisms were recovered from iron (30-fold more) compared to PVC pipe sections. However, the majority of isolates from the PVC biofilm (8 of 10, 80 %) were capable of Mn-oxidation while only 35 % (11 of 31) of isolates from the iron biofilm sample demonstrated Mn-oxidation. This research demonstrates the importance of the different interactions between water and the infrastructure used for its supply in producing safe drinking water. / Master of Science

Traffic congestion and safety has become a major issue in the modern world's commute. Congestion has been causing people to travel billions of hours more and to purchase billions of gallons of fuel extra which account to congestion cost of billions of dollars. Autonomous driving vehicles have been one solution to this problem because of their huge impact on efficiency, pollution, and human safety. Also, extensive research has been carried out on control design of vehicular platoons because a further improvement in traffic throughput while not compromising the safety is possible when the vehicles in the platoon are provided with better predictive abilities. Motion control is a key area of autonomous driving research that handles moving parts of vehicles in a deliberate and controlled manner. A widely worked on problem in motion control concerned with time parameterized reference tracking is trajectory tracking. Having an efficient and effective tracking algorithm embedded in the autonomous driving system is the key for better performance in terms of resources consumed and tracking error. Many tracking control algorithms in literature rely on an accurate model of the vehicle and often, it can be an intimidating task to come up with an accurate model taking into consideration various conditions like friction, heat effects, ageing processes etc. And typically, control algorithms rely on periodic execution of the tasks that update the control actions, but such updates might not be required, which result in unnecessary actions that waste resources. The main focus of this work is to design an intermittent model-free optimal control algorithm in order to enable autonomous vehicles to track trajectories at high-speeds. To obtain a solution which is model-free, a Q-learning setup with an actor-network to approximate the optimal intermittent controller and a critic network to approximate the optimal cost, resulting in the appropriate tuning laws is considered. / Master of Science / A risen research effort in the area of autonomous vehicles has been witnessed in the past few decades because these systems improve safety, comfort, transport time and energy consumption which are some of the main issues humans are facing in the modern world’s highway systems. Systems like emergency braking, automatic parking, blind angle vehicle detection are creating a safer driving environment in populated areas. Advanced driver assistance systems (ADAS) are what such kind of systems are known as. An extension of these partially automated ADAS are vehicles with fully automated driving abilities, which are able to drive by themselves without any human involvement. An extensively proposed approach for making traffic throughput more efficient on existing highways is to assemble autonomous vehicles into platoons. Small intervehicle spacing and many vehicles constituting each platoon formation improve the traffic throughput significantly. Lately, the advancements in computational capabilities, in terms of both algorithms and hardware, communications, and navigation and sensing devices contributed a lot to the development of autonomous systems (both single and multiagent) that operate with high reliability in uncertain/dynamic operating conditions and environments. Motion control is an important area in the autonomous vehicles research. Trajectory-tracking is a widely studied motion control scenario which is about designing control laws that force a system to follow some time-dependent reference path and it is important to have an effective and efficient trajectory-tracking control law in an autonomous vehicle to reduce the resources consumed and tracking error. The goal of this work is to design an intermittent model-free trajectory tracking control algorithm where there is no need of any mathematical model of the vehicle system being controlled and which can reduce the controller updates by allowing the system to evolve in an open loop fashion and close the loop only when an user defined triggering condition is satisfied. The approach is energy efficient in that the control updates are limited to instances when they are needed rather than unnecessary periodic updates. Q-learning which is a model-free reinforcement learning technique is used in the trajectory tracking motion control algorithm to make the vehicles track their respective reference trajectories without any requirement of their motion model, the knowledge of which is generally needed when dealing with a motion control problem. The testing of the designed algorithm in simulations and experiments is presented in this work. The study and development of a vehicle platform in order to perform the experiments is also discussed. Different motion control and sensing techniques are presented and used. The vehicle platform is shown to track a reference trajectory autonomously without any human intervention, both in simulations and experiments, proving the effectiveness of the proposed algorithm.

Internet of Things require a continuous power supply for longevity and energy harvesting from ambient sources enable sustainable operation of such embedded devices. Using selfpowered power supply gives raise two scenarios, where there is surplus or scarce harvested energy. In situations where the harvester is capable of harvesting beyond its storage capacity, the surplus energy is wasted. In situations where the harvester does not have sufficient resources, the sparse harvested energy can only transiently power the device. Transiently powered devices, referred to as intermittent computing devices, ensure forward progress by storing checkpoints of the device state at regular intervals. Irrespective of the availability of energy, the device should have adequate security. This thesis addresses the security of energy harvested embedded devices in both energy scenarios. First, we propose precomputation, an optimization technique, that utilizes the surplus energy. We study two cryptographic applications, namely bulk encryption and true random number generation, and we show that precomputing improves energy efficiency and algorithm latency in both applications. Second, we analyze the security pitfalls in transiently powered devices. To secure transiently powered devices, we propose the Secure Intermittent Computing Protocol. The protocol provides continuity to underlying application, atomicity to protocol operations and detects replay and tampering of checkpoints. Both the proposals together provide comprehensive security to self-powered embedded devices. / Master of Science / Internet of Things(IoT) is a collection of interconnected devices which collects data from its surrounding environment. The data collected from these devices enable emerging technologies like smart home and smart cities, where objects are controlled remotely. With the increase in the number of such devices, there is a demand for self-powered devices to conserve electrical energy. Energy harvesters are suitable for this purpose because they convert ambient energy into electrical energy to be stored in an energy buffer, which is to be used when required by the device. Using energy harvesters as power supply presents us with two scenarios. First, when there is sufficient ambient energy, the surplus energy, which is the energy harvested beyond the storage capacity of the buffer, is not consumed by the device and thus, wasted. Second, when the harvested energy is scarce, the device is forced to shutdown due to lack of power. In this thesis, we consider the overall security of an energy harvested IoT device in both energy scenarios. We optimize cryptographic algorithms to utilize the surplus energy and design a secure protocol to protect the device when the energy is scarce. Utilizing both the ideas together provides adequate security to the Internet of Things.

Ett avgörande steg i avloppsvattenrening med aktivslammetoden är att slammet kan avskiljas från det renade vattnet. Detta sker oftast i sedimenteringsbassänger. Sedimenteringsproblem är dock vanliga på många avloppsreningsverk, vilket kan leda till att föroreningar följer med utgående vatten. Studier om slamegenskaper är därför viktiga för att öka förståelsen för vilka faktorer som påverkar sedimenteringen och vad som kan göras för att minska problemen. I detta examensarbete har ett mindre avloppsreningsverk i Lövsta utanför Uppsala studerats. Ungefär en tredjedel av flödet till verket kommer från ett närliggande slakteri. Verket har återkommande problem med flytslam i slutsedimenteringsbassängen. Syftet med arbetet var att – genom litteraturstudier, provtagning, fullskaleförsök och analys – identifiera orsaker till flytslamproblemen. Även förslag till åtgärder skulle läggas fram. En utvärdering av reningsprocessen genomfördes dels utifrån befintliga mätdata, dels genom utförligare provtagningar och mätningar som gjordes under en treveckorsperiod i oktober. Höga nitrathalter observerades i vattnet, särskilt i den utjämningstank där flödesutjämning och förbehandling av slakterivattnet sker. De höga nitrathalterna, i kombination med en lång slamuppehållstid i slutsedimenteringsbassängen, bedömdes vara orsaken till flytslambildningen eftersom båda dessa faktorer gynnar uppkomsten av kvävgas genom denitrifikation. Det är denna gas som lyfter slammet från botten av bassängen till ytan. Två möjliga åtgärder för att lösa flytslamproblemen bedömdes vara genomförbara. Den ena var att öka bortpumpningen av slam från botten av slutsedimenteringsbassängen, för att förkorta slamuppehållstiden. Den andra var att denitrifiera vattnet innan det når slutsedimenteringen. Av dessa förslag ansågs det senare vara mer tilltalande ur både ekonomisk och miljömässig synvinkel. En strategi för att denitrifiera vattnet bedömdes vara intermittent luftning av utjämningstanken. Denna luftningsstrategi tillämpades under en försöksperiod på tio veckor. Nitrathalterna mättes en eller två gånger i veckan under försöksperioden. En sänkning av nitrathalterna observerades: från 182 mg/l till som lägst 60 mg/l i utjämningstanken och från 65 mg/l till som lägst 18 mg/l i luftningsbassängen. Sänkningen var dock inte tillräcklig för att förhindra flytslambildning i sedimenteringsbassängerna. Den ofullständiga denitrifikationen berodde troligtvis på för låga BOD-halter i utjämningstanken. Vidare undersökningar behövs för att utvärdera och optimera kvävereningen genom intermittent luftning. / One of the most crucial steps in wastewater treatment with activated sludge is the separation of sludge from the treated effluent. This is most often done by sedimentation in clarifiers. Sedimentation problems are, however, common in many wastewater treatment plants, causing higher concentrations of pollutants in the effluent. Research on sludge characteristics is therefore important to increase the knowledge about which factors affect the sludge settling properties and what can be done to minimize problems. In this master thesis a small wastewater treatment plant in Lövsta outside Uppsala, Sweden, was investigated. About a third of the influent water to the plant comes from a slaughterhouse situated nearby. The plant suffers from recurrent problems with rising sludge in the secondary clarifier. The purpose of this thesis was to – through literature studies, sampling, full scale experiments and analysis – identify causes for the rising sludge problem. Also, suggestions to remedy the problem were to be presented. An evaluation of the treatment process was conducted from existing measurement data and from sampling and measuring done for three weeks in October. High concentrations of nitrate were found in the water, especially in the equalization tank, where flow equalization and primary treatment of the slaughterhouse wastewater takes place. The high concentrations of nitrate, in combination with a long sludge retention time in the secondary clarifier, were judged to be the reason for the formation of rising sludge. Both of these factors stimulate the development of nitrogen gas through denitrification. This gas lifts the sludge from the bottom of the clarifier to the water surface. Two possible solutions to the rising sludge problem were considered feasible. One was to increase the pumping of sludge from the bottom of the secondary clarifier, to decrease the sludge retention time. The second was to denitrify the water before it reaches the clarifiers. Of these two suggestions, the second was regarded as more appealing from both an economical and an environmental point of view. One method to denitrify the water was deemed to be intermittent aeration in the equalization tank. This aeration strategy was implemented for ten weeks. Nitrate concentrations were measured one or two times a week for this period of time. A decrease in nitrate concentrations was observed: from 182 mg/L to at its lowest 62 mg/L in the equalization tank, and from 65 mg/L to at its lowest 18 mg/L in the aeration tank. The decrease was, however, not enough to prevent formation of rising sludge in the clarifiers. The incomplete denitrification process was thought to be due to low concentrations of BOD in the equalization tank. Further studies need to be carried out to evaluate and optimize the nitrogen removal through intermittent aeration.

Bakgrund: I Sverige lever cirka 5000 personer med spinalskada. Där spinalskadan lett till nedsatt blåsfunktion är ren intermittent kateterisering (RIK) den metod som rekommenderas i första hand. Syfte: Att undersöka hur personer med traumatisk spinalskada som använder ren intermittent kateterisering (RIK) upplever detta. Syftet var även att ta reda på vilka hanteringsstrategier som finns för att underlätta det dagliga livet. Metod: En kvalitativ metod med semistrukturerade intervjuer användes där fem personer med traumatisk spinalskada som använder RIK intervjuades. Resultat: Att behöva tillägna sig metoden väckte blandade känslor. Män upplevde det lättare att RIKa jämfört med kvinnor. Den egna kompetensen och kunnandet om metoden RIK ökade med tiden och de hittade nya hanteringsstrategier för att underlätta vardagen. Informanterna var medvetna om vikten av god hygien för att undvika urinvägsinfektioner. Däremot framgick det inte om informanterna var medvetna om kopplingen mellan vikten av regelbunden RIKning, residualurin i blåsan och uppkomsten av urinvägsinfektioner. Slutsats: Personer som använder RIK upplever det som nödvändigt och avgörande för att kunna leva ett normalt liv. Hanteringsstrategier är planering och anpassande av metoden efter fysisk förmåga och den egna vardagen. Behovet av stöd hos personer med spinalskada som använder RIK är individuellt och varierar. Adekvat stöd och utbildning underlättar och hjälper personer med nedsatt blåsfunktion som använder RIK att ta kontroll över utövandet och främjar följsamheten och långsiktig hälsa avseende urinvägarna. / Background: About 5,000 people in Sweden live with a spinal injury. Where the spinal injury leads to impaired bladder function, clean intermittent catheterization (CIC) is the method recommended in the first place. Aim: To examine  how individuals  with traumatic  spinal injury  using clean  intermittent catheterization experience the method. The aim was also to find out coping strategies available to facilitate daily life. Methods: A qualitative approach with semi-structured interviews was used where five people with traumatic spinal injury were interviewed. Results: The need to use CIC brought about mixed feelings among informants. Men felt that it was easier for them to use clean intermittent catheterization compared to women. Their expertise and knowledge increased with time and they found new coping strategies to facilitate everyday life. The informants were aware of the importance of good hygiene to prevent urinary tract infections. However, it was not clear if the informants were aware of the connection between the importance of using clean intermittent catheterization regularly, residual urine in the bladder and the occurrence of  urinary  tract  infections. Conclusion: People who use CIC experience it as essential and vital in order to live a normal life. The need for support of people with spinal injury who use CIC is individual and varies. Adequate support and training for people with impaired bladder function using CIC facilitates and helps them to take control initially and promotes an ongoing adherence and long-term health regarding urinary tract.

Part of the aim of this thesis was to explore a model for producing very fast saccade latencies in the 80 to 120ms range. Its primary motivation was to explore a possible interaction by uniquely combining three independent saccade factors: the gap effect, target-feature-discrimination, and saccadic inhibition of return (IOR). Its secondary motivation was to replicate (in a more conservative and tightly controlled design) the surprising findings of Trottier and Pratt (2005), who found that requiring a high resolution task at the saccade target location speeded saccades, apparently by disinhibition. Trottier and Pratt’s finding was so surprising it raised the question: Could the oculomotor braking effect of saccadic IOR to previously viewed locations be reduced or removed by requiring a high resolution task at the target location? Twenty naïve untrained undergraduate students participated in exchange for course credit. Multiple randomised temporal and spatial target parameters were introduced in order to increase probability of exogenous responses. The primary measured variable was saccade latency in milliseconds, with the expectation of higher probability of very fast saccades (i.e. 80-120ms). Previous research suggested that these very fast saccades could be elicited in special testing circumstances with naïve participants, such as during the gap task, or in highly trained observers in non-gap tasks (Fischer & Weber, 1993). Trottier and Pratt (2005) found that adding a task demand that required naïve untrained participants to obtain a feature of the target stimulus (and to then make a discriminatory decision) also produced a higher probability of very fast saccade latencies. They stated that these saccades were not the same as saccade latencies previously referred to as express saccades produced in the gap paradigm, and proposed that such very fast saccades were normal. Carpenter (2001) found that in trained participants the probability of finding very fast saccades during the gap task increased when the horizontal direction of the current saccade continued in the same direction as the previous saccade (as opposed to reversing direction) – giving a distinct bimodality in the distribution of latencies in five out of seven participants, and likened his findings to the well known IOR effect. The IOR effect has previously been found in both manual key-press RT and saccadic latency paradigms. Hunt and Kingstone (2003) stated that there were both cortical top-down and oculomotor hard-wired aspects to IOR. An experiment was designed that included obtain-target-feature and oculomotor-prior-direction, crossed with two gap level offsets (0ms & 200ms-gap). Target-feature discrimination accuracy was high (97%). Under-additive main effects were found for each factor, with a three-way interaction effect for gap by obtain-feature by oculomotor-prior-direction. Another new three-way interaction was also found for anticipatory saccade type. Anticipatory saccades became significantly more likely under obtain-target-feature for the continuing oculomotor direction. This appears to be a similar effect to the increased anticipatory direction-error rate in the antisaccade task. These findings add to the saccadic latency knowledge base and in agreement with both Carpenter and Trottier and Pratt, laboratory testing paradigms can affect saccadic latency distributions. That is, salient (meaningful) targets that follow more natural oculomotor trajectories produce higher probability of very fast latencies in the 80-120ms range. In agreement with Hunt and Kingstone, there appears to be an oculomotor component to IOR. Specifically, saccadic target-prior-location interacts differently for obtain-target-feature under 200-ms gap than under 0ms-gap, and is most likely due predominantly to a predictive disinhibitory oculomotor momentum effect, rather than being due to the attentional inhibitory effect proposed for key-press IOR. A new interpretation for the paradigm previously referred to as IOR is offered that includes a link to the smooth pursuit system. Additional studies are planned to explore saccadic interactions in more detail.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 6 uppsatser.

La colonisation nasale à Staphylococcus aureus est un important facteur de risque d’infection par cette bactérie chez l’homme. Le rôle de la colonisation extra-nasale dans la physiopathologie des infections liées à la souche de colonisation est incertain. Contrairement aux porteurs intermittents et aux non porteurs, les porteurs persistants ont un risque accru d’infection à S. aureus notamment chez les patients dialysés. Nous avons développé et proposé une nouvelle stratégie applicable aux soins courants pour prédire rapidement le statut de portage nasal persistant de S. aureus dans l’optique de faire bénéficier les porteurs les plus à risque d’infection à S. aureus de mesures de prévention ciblées. Nous avons montré, à travers l’étude des réservoirs pharyngé et digestif, qu’il existe une grande diversité génétique des souches de S. aureus isolées des muqueuses. Enfin, différentes hypothèses ont été investiguées pour déterminer les facteurs microbiologiques associés à la persistance du portage nasal de S. aureus. Ces résultats préliminaires suggèrent que les souches isolées de colonisation nasale persistante et intermittente ont des caractéristiques très similaires / Staphylococcus aureus nasal carriage is a major risk factor of infection with this bacterium in humans. The role of S. aureus extra-nasal carriage in endogenous infections remain elusive. By contrast to intermittent carriers and noncarriers, persistent carriers have a higher risk of S. aureus infection, especially in dialysis patients. We have developed and validated an algorithm to predict the nasal carriage state in clinical practice for proposing decolonization to carriers having the highest risk of S. aureus infection. We found a high diversity between S. aureus strains colonizing the nose, the throat and the rectum, suggesting that extra-nasal carriage could be an additional risk factor of S. aureus infection. Finally, we studied several bacterial determinants of persistent nasal carriage. Our preliminary results suggest that S. aureus isolated in persistent and intermittent carriers harboured similar features

Vid elektroencefalografi (EEG) används intermittent ljusstimulering för att detektera eventuell fotoparoxysmal reaktion (PPR) hos patienter, som tecken på en fotosensitivitet och stöd för en misstanke om epilepsi. Intermittent ljusstimulering innebär att patienten exponeras för en stroboskoplampa som ger ljus med frekvenser mellan 1–60 Hz. PPR karaktäriseras av spikes, spike-waves eller polyspike-waves som uppkommer bilateralt och synkront, symmetriskt och generaliserat. Intermittent ljusstimulering är en provokation som utförs vid rutin-EEG som tolkas på Skånes universitetssjukhus mellan 6 månader och 70 års ålder. Studier har dock visat att PPR sällan provoceras fram i äldre åldersgrupper. För äldre åldersgrupper kan det istället vara till större förmån att använda andra former av provokationer. Syftet med studien var att kartlägga förekomsten av PPR i olika åldersgrupper. Åldersfördelningen studerades på patienter med PPR som undersökts med rutin-EEG vilka tolkades på Skånes universitetssjukhus under perioden 2017-2020. Av 4050 rutin-EEG hade 3821 utfört intermittent ljusstimulering. Av dessa hade 1,4 % PPR med ett medelvärde av åldern på 17 år och standardavvikelse på 10 år. PPR var vanligare hos yngre (p<0,001) och 91 % av patienterna med PPR var under 30 år. PPR var även vanligare hos kvinnor (p<0,001) och motsvarade 84 % av undersökningarna med PPR. Konklusionen av studien är att PPR är vanligare hos kvinnor och patienter under 30 år. / Electroencephalography (EEG) uses intermittent photic stimulation to detect possible photoparoxysmal response (PPR) in patients, as a sign of photosensitivity and as a contribution in the diagnosis of a suspected epilepsy. Intermittent photic stimulation means that the patient is exposed to flashing lights from a stroboscope lamp that provides light with frequencies between 1–60 Hz. PPR is characterized by spikes, spike-waves or polyspike-waves that occur bilaterally and synchronously, symmetrically and generalized. Intermittent photic stimulation is a provocation performed during routine-EEG that is interpreted at Skåne university hospital between 6 months and 70 years of age. However, studies have shown that PPR is rarely provoked in older age groups. For older age groups, it may instead be a greater advantage of using other forms of provocative methods. The purpose of this study was to map how common PPR is in different age groups. The age distribution was studied on patients with PPR who were examined with a routine EEG that was interpreted at Skåne university hospital during the period 2017-2020. Of the 4050 routine EEG, 3821 had performed intermittent photic stimulation. Of these 1.4 % had PPR with a mean age value of 17 years and a standard deviation of 10 years. PPR was more common in younger age groups (p<0.001) and 91% of the patients with PPR were younger than 30 years old. PPR was also more common in females (p <0.001), corresponding to 84 % of the examinations with PPR. The conclusion of the study is that PPR is more common in females and in patients younger than 30 years old.

Utveckling av det moderna samhället och den fortsatt accelererande energiintensiva tillvaro människan lever i sätter stor press på klimatet. För att nå de hållbarhetsmål FN satt upp som bland annat innebär minskade utsläpp och effektivare energianvändning krävs krafttag i det globala energisystemet. För att öka andelen modern och ren energi krävs att sol- och vindkraft prioriteras. Ett stort problem med dessa energikällor är dess intermittenta produktion vilken alstrar oregelbunden elektricitet och ställer nya krav på elnätet. För att underlätta implementering av förnybara energikällor på det nationella elnätet och i mindre energisystem undersöks i den här rapporten de förutsättningar som finns för att integrera batterienergilagringssystem i kombination med intermittenta energikällor. Rådande förutsättningar redogörs för i en omfattande litteraturundersökning där bland annat elnätets funktion, lovande batteriteknologier, ekonomiska incitament för batterienergilagring och framtidspotential undersöks. Ett globalt engagemang för att öka andelen förnybar energi med hjälp av batterienergilagring i det globala energisystemet identifieras. Vidare visas batterienergilagringssystem har stor potential att minimera den belastning intermittenta energikällor har på elnätet. Potentialen begränsas i nuläget av rådande politiska styrmedel och elmarknadens utformning då en småskalig elproducent idag gynnas av att direkt mata ut överskottsel på elnätet istället för att använda energilagring. Med en växande andel intermittent elproduktion förväntas minskade begränsningar och batterienergilagring kopplat till elproduktion bli mer lönsamt. / The development of the modern society and the global continuously accelerating energy intensive way of living is putting stress on the climate. In order to achieve the UNs set of sustainability goals, including reduced emissions and more efficient use of energy, vigorous actions in the global energy system is required. To increase the share of clean and modern energy generation a larger quantity of solar and wind power is required. Due to weather dependency these resources generate intermittent electricity which will put new challenges on the grid.   To facilitate the implementation of intermittent energy sources on the national grid and in smaller energy systems this report aims to investigate current prerequisites on integrating battery energy storage systems and intermittent resources to increase the share of clean energy sources in the power system. Current prerequisites are presented as the result of an extensive literature study where the electrical grid, promising battery technologies, financial incentives for battery energy storage and future potential is examined.   A global commitment to increase the share of renewable energy sources using battery energy storage system in the global energy system is identified. Furthermore, battery energy storage systems are shown to have great potential in limiting the negative impact of intermittent energy sources on the electrical grid. This potential is currently being limited by existing political control means and the design of the electricity market such that small producers are benefitted by directly supplying the grid with excess electricity instead of using energy storage. With a growing share of intermittent power generation these limitations are expected to ease and battery energy storage systems in connection with power production becoming more profitable.​