The challenge of managing the present and projected electricity energy needs along with targets of mitigating CO2 emissions leads to the need for energy systems to reduce reliance on fossil fuels and rely on more energy from renewable sources. The integration of more renewable energy technologies to meet present and future electricity demand leads to more challenges in matching the trade-o between economic, resilient, reliable and environmentally friendly solutions. Energy storage technologies can provide temporal resilience to energy systems by solving these challenges. Energy storage systems can improve the reliability of energy systems by reducing the mismatch between supply and demand due to the intermittency of renewable energy sources. This thesis presents a comprehensive analysis of various energy storage systems, analyzing their speci c characteristics including capital cost, e ciency, lifetime and their usefulness in di erent applications. Di erent hybrid energy systems are designed to analyze the impacts of renewable and non-renewable energy sources and energy storage systems in residential on-grid and o -grid buildings and districts. An optimization analysis is performed to determine which technology combinations provide the most economic solution to meet electric energy demands. The optimization analysis is solved using the "energy hub" model formulation which optimizes energy system operation and capacity of di erent technologies. Di erent energy systems can be optimized by using energy hub model, including multiple input energy carriers that are converted to multiple energy outputs. The analysis in this thesis employs a building simulation tool to model residential building, and real data sets to explore the di erent electricity pro le e ects on the results. The environmental e ect of hybrid energy systems comparing with base cases of conventional energy systems or grid connection are also analyzed. Results show that the feasibility of energy storage systems is a factor of di erent variables including capital cost of energy converters and energy storage systems, cost of input streams (grid electricity in on-grid systems and diesel fuel in o -grid systems, energy demand pro les and availability of renewable energy sources. The on-grid single and district buildings do not select storage technologies at current costs due to cheap grid electricity. Reduction in the cost of renewable energy technologies and/or energy storage systems (e.g. Li-ion batteries) results in more energy storage installations. In o -grid systems (single buildings and districts), Li-ion battery and pumped hydro are the main storage systems that can balance the daily and seasonal energy demands. / Graduate / 2021-03-13

Sustainable energy management becomes more important due to the ever more actual problems of environmental pollution and limited natural resources. The fuel cell technology is one of the most attractive solutions in this sense. During the past decades fuel cells have been investigated and demonstrated for several applications. One of the most attractive applications is using fuel cell system for stationary energy cogeneration (CHP), since they are capable of producing thermal energy and power with higher efficiencies and in a more environmentally friendly way than most of the conventional commercial techniques. The purpose of this work is to investigate the feasibility of integrating a PEMFC system with a commercial greenhouse and to assess the mutual benefits deriving from this integration. The main task of this connection is to recover the low temperature wasted heat delivered by the PEMFC system and by the fuel reforming process in order to meet the thermal energy demand of a commercial greenhouse. In this study an energy analysis was performed in order to evaluate the energetic performance of the system. To achieve this aim, first, a model of the whole system was developed in TRNSYS environment. In addition to the aforesaid, a sensitivity analysis was also carried out varying the main influencing operating parameters in order to evaluate an optimal configuration of the system. Considering a commercial greenhouse’s usual thermal and electrical demand, the results shows that by integrating a 3 KW fuel cell system, able to cover approximately the 25% of the electricity requested during the year, and taking into account both heat recovery from the fuel cell system and the ones from the fuel reforming, roughly 30% of the heating demand of a 1000 m2 commercial greenhouse can be supplied.

Residences require electricity for lights, appliances, and space cooling and thermal energy for space and domestic water heating. Total energy systems (TES) which provide both electricity and thermal energy can meet these needs more effectively than conventional systems because thermal energy rejected during the on-site production of electricity can be recovered to meet the heating loads. TESs based on fuel cell systems are particularly attractive because of their high efficiencies, quiet operation, and small size. This research evaluates a TES consisting of a fuel cell sub-system (FCS), an electric heat pump (HP), and a thermal storage tank (TS). A model of a grid-independent, electric load following TES is developed to determine the energy required to meet the hourly average electric and thermal loads of the residence. The TES uses a heat pump to provide space cooling. Electricity for air conditioning, lights, and appliances is provided by the FCS. Space heating and water heating of the residence are provided by the thermal energy available from the FCS. The TES is designed so that, heating requirements that exceed the heat available from the FCS can be satisfied by the HP and an electric water heater. A thermal storage tank is used to store and transfer thermal energy from the FCS to the residence. The results of the research include a comparison of the energy use by the TES to the energy use by conventional residential energy systems; an evaluation of the effects of climatic conditions on system performance and energy use; and a comparison of the life-cycle cost of the TES and conventional residential energy systems. The results indicate that total energy systems can reduce primary energy use by as much as 40 percent, but that to be economically attractive, the FCS cost must be reduced to approximately $500/kWe. / Master of Science

A decomposition methodology based on the concept of "thermoeconomic isolation" applied to the synthesis/design and operational optimization of a stationary cogeneration proton exchange membrane fuel cell (PEMFC) based total energy system (TES) for residential/commercial applications is the focus of this work. A number of different configurations for the fuel cell based TES were considered. The most promising set based on an energy integration analysis of candidate configurations was developed and detailed thermodynamic, kinetic, geometric, and economic models at both design and off-design were formulated and implemented. A decomposition strategy called Iterative Local-Global Optimization (ILGO) developed by Muñoz and von Spakovsky was then applied to the synthesis/design and operational optimization of the fuel cell based TES. This decomposition strategy is the first to successfully closely approach the theoretical condition of "thermoeconomic isolation" when applied to highly complex, non-linear systems. This contrasts with past attempts to approach this condition, all of which were applied to very simple systems under very special and restricted conditions such as those requiring linearity in the models and strictly local decision variables. This is a major advance in decomposition and has now been successfully applied to a number of highly complex and dynamic transportation and stationary systems. This thesis work presents the detailed results from one such application. / Master of Science

Urban areas house most of the global population and are also responsible for large shares of global greenhouse gas emissions. Cities and municipalities thus play a significant role in modern society to achieve an energy transition to renewable energy sources and to adapt to climate change. Achieving such a transition is a difficult process due to the high energy density and complexity of urban multi-energy systems. This is further exacerbated by the adverse effect future climate hazards will likely have on urban infrastructure. Despite this, energy development and climate adaptation plans are often researched and drafted in a disjointed manner. In many instances, future energy strategies do not consider climate impacts, whereas climate adaptation tactics disregard energy production. This study proposed that such mutually exclusive analysis and decision-making increases the vulnerability of planned and optimised future urban energy systems. Investigating the Swedish municipality Malmö, the study focused on achieving a future energy transition in its electricity network and then considering potential climate change impacts. Current urban energy plans and capacity were used to forecast the renewable energy potential for 2030 in Malmö’s geographical area. This formed the basis for modelling an optimised hybrid renewable energy system for the municipality using HOMER Grid. Based on future climate data and Malmö’s climate adaptation plans, this system was then evaluated in terms of impacts from climate hazards. The results indicated that Malmö’s current energy plans would expose a large share of their energy infrastructure to risk of damage from climate hazards. Thus, the vulnerability of the optimised energy system is indeed heightened when disregarding climate change impacts in the planning phase. If climate change and energy transition strategies are developed conjointly, urban energy system resilience could likely be increased significantly.

Historic buildings, buildings built before 1945, represent a third of the total building stock in Sweden. While implementing energy efficiency measures (EEMs) on historic buildings it is important to consider heritage values. This thesis aims to investigate impacts on primary energy use and CO2 emissions while using life cycle cost (LCC) optimization on historic buildings in three studied cases: reference case with no implemented EEMs (case 1), lowest possible LCC (case 2) and a decrease by 50% in energy use (case 3). As a case study 920 historic buildings divided into twelve typical buildings (6 wood buildings, 1w-6w, and 6 stone buildings, 1s-6s) in the downtown area of Visby, Sweden, are used. Within the scope of the thesis, how to achieve the most profitable EEMs and how the profitability of energy renovation varies between the typical buildings in the studied cases will be analyzed also. An interdisciplinary method is applied in the thesis that considers both heritage values and energy savings. However, the keystone of the thesis is the use of the program Optimal Energy Retrofit Advisory-Mixed Integer Linear Programming (OPERA-MILP), which is a part of the interdisciplinary method. With the use of OPERA-MILP, the cost-optimal energy renovation strategy is obtained for a building. The program takes into account all energy-related investment costs, as well as the investment and operation costs for the heating system, during a set time period. The results show unique packages of EEMs for each of the twelve typical buildings with a potential to lower the total LCC by between 4-11% in the building stock and simultaneously decrease the energy use by more than 50%. The thesis also shows a possible decrease in primary energy use from 24%-57%. The CO2 emissions vary significantly depending on what assumptions are made related to electricity production and biomass use; the results show increases up to 224% in CO2 emissions but also decreases up to 85%. All typical buildings are economically viable to energy renovate. The LCC savings are between 1.4-11.8 SEK with a life cycle set to 50 years for every annually saved kWh, except for case 3 where cost is incurred for every annually saved kWh, 10.0-17.2 SEK, for a number of the typical buildings. / Historiska byggnader, byggnader uppförda före 1945, utgör en tredjedel av det totala byggnadsbeståndet i Sverige. Historiska byggnader har ofta kulturhistoriska värden som måste beaktas vid energieffektiviseringar. Detta examensarbete syftar till att undersöka påverkan på primärenergianvändning och CO2-utsläpp genom optimering av livscykelkostnaderna (LCC) för historiska byggnader. Som fallstudie används 920 historiska byggnader i Visbys innerstad, indelade i tolv olika typbyggnader (6 träbyggnader, 1w-6w, och 6 stenbyggnader, 1s-6s). Tre fall undersöks: referensfall utan implementerade energieffektiviseringsåtgärder (fall 1), lägsta möjliga LCC (fall 2) och en minskning av energianvändningen med 50 % (fall 3). Inom examensarbetets kommer även de mest lönsamma energieffektiviseringsåtgärderna tas fram. Examensarbetet kommer också att visa hur lönsamheten för energirenovering varierar mellan de olika typbyggnaderna. Vid utförandet av examensarbetet tillämpas en tvärvetenskaplig metod som beaktar både kulturhistoriska värden och energibesparing. Tyngdpunkten ligger dock på användningen av programmet Optimal Energy Retrofit Advisory-Mixed Integer Linear Programming (OPERA-MILP), som är en del av den tvärvetenskapliga metoden. Med användningen av OPERA-MILP erhålls den kostnadsoptimala energieffektiviseringsstrategin för en byggnad. Programmet beaktar alla energirelaterade investeringskostnader, samt investering- och driftkostnader för värmetillförselsystem, under en bestämd tidsperiod. Resultaten visar unika energieffektiviseringspaket för de olika typbyggnaderna med en potential att sänka totala LCC för byggnadsbeståndet med 4-11 % och samtidigt minska energianvändningen med mer än 50 %. Examensarbetet visar också en möjlig minskning i primärenergianvändning med 24-57 %. CO2-utsläppen varierar mycket beroende på vilka antaganden görs relaterat till elektricitetsproduktion och användning av biomassa; resultaten visar ökningar upp till 224 % i CO2-utsläpp men också minskningar ned till 85 %. Samtliga typbyggnader är ekonomiskt lönsamma att energirenovera med LCC-besparingar på 1,4-11,8 SEK med en livscykel satt till 50 år för varje årligen sparad kWh, förutom i fall 3 då kostnader uppstår för varje årligen sparad kWh med 10,0-17,2 SEK, för ett antal av typbyggnaderna. / Potential and Policies for Energy Efficiency in Swedish Buildings Built Before 1945 (Stage II) - Energy Systems Analysis

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Space heating and cooling, as required for chicken poultry farming, is an energy intensive operation. Due to the continuous rise in the prices of fossil fuel, water and electricity, there is a need to develop renewable and sustainable energy systems that minimise the use of fuel or electricity, for heating, and water, for cooling of air. The HYDROSOL (HYDro ROck SOLar) system, developed at Stellenbosch University, is such a renewable energy system that potentially provides a low cost solution. Instead of using conventional gas and electricity heaters for the heating of air during winter, the HYDROSOL system collects solar heat, stores it in a packed bed of rocks and dispatches the heat as required. During hot summer days, when cooling is needed, the rocks are cooled during the night when the ambient temperatures are low and/ or by evaporative cooling by spraying water onto them. During the day, hot air is then cooled when it passes through the colder rocks with minimal water consumption compared to current systems. In this thesis, a prototype of the HYDROSOL system is presented, designed and built for experimental testing. A transient 2-D thermo flow model is developed and presented for the analytical and experimental performance evaluation of this system for solar heating and night air cooling operation. This model is used to conduct a parametric study on HYDROSOL to gain a better understanding of the operation and control of the system. The HYDROSOL concept is intended to be used for heating and cooling of residential buildings, office suites, warehouses, shopping centres, food processing industries e.g. drying of foods, and various agricultural industries e.g. greenhouses. In this thesis, a HYDROSOL system is developed mainly for poultry broiler houses in South Africa focussing on convective dry cooling, charging the rock bed with night-time ambient air, and convective heating, harvesting solar heat during the day, with different modes of operation available. / AFRIKAANSE OPSOMMING: Ruimte verhitting en verkoeling, soos benodig vir hoender pluimvee boerdery, is ‘n energie intensiewe bedryf. As gevolg van die voortdurende styging in fossiel brandstof-, water- en elektrisiteitpryse, het ‘n behoefte ontstaan om hernubare en volhoubare energie-stelsels te ontwikkel wat minder brandstof of elektrisiteit, vir verhitting, en water, vir verkoeling van lug, gebruik. Die HYDROSOL (HYDro ROck SOLar) stelsel, wat ontwikkel is by die Universiteit van Stellenbosch, is ‘n hernubare energie-stelsel wat ‘n potensiële lae koste oplossing bied. In plaas daarvan om konvensionele gas en elektrisiteit verwarmers vir verhitting van lug gedurende die winter te gebruik, maak HYDROSOL gebruik van son warmte, stoor dit in `n gepakte bed van klip en onttrek die warmte soos benodig. Gedurende die warm somer dae wanneer verkoeling benodig word, word die klippe gedurende die nag, met kouer omgewings lug en/of met verdampingsverkoeling, deur water op die klippe te spuit, afgekoel. Gedurende die dag word warm lug afgekoel deur die lug oor die koue klippe te forseer met minimale waterverbruik in vergelyking met huidige stelsels. ‘n Prototipe van die HYDROSOL word voorgestel, ontwerp en gebou vir eksperimentele doeleindes. ‘n 2-D tyd afhanklike termo- vloei model word voorgestel vir die analitiese en eksperimentele verrigting evaluering vir son verhitting en nag lug verkoeling. Hierdie model word gebruik om ‘n parametriese studie te doen om die werking en beheer van HYDROSOL beter te verstaan. Die HYDROSOL stelsel is bedoel om die verwarming en verkoeling vereistes van residensiële geboue, kantoor areas, pakhuise, winkelsentrums, voedsel verwerking nywerhede, soos bv. die droging van voedsel, en verskeie landboubedrywe, soos bv. kweekhuise, te bevredig. In hierdie tesis word ‘n HYDROSOL stelsel, hoofsaaklik vir pluimvee kuikenhuise in Suid- Afrika, ondersoek en fokus op die droë verkoeling, deur die rotsbed te laai gedurende die nag, asook droë- verhitting, wat gebruik maak van son energie gedurende die dag en kan beheer word op verskillende maniere.

Wind power is a rapidly growing industry worldwide, both on- andoffshore. Most of the good locations onshore in continental Europeare in use today, which has prompted a move offshore in recentyears. Europe has by far the most offshore wind turbinesinstalled, mostly located in the North sea.The low hanging fruits are locations with relatively shallowwaters (up to 45-50 meters), a high and steady wind speed and isclose to grid connections onshore. Big parts of the North Sea aresuitable for this, but many places with good wind conditionsworldwide are too deep. The next step for the industry is to moveto these deeper waters, with the help of floating wind turbines.The first prototype floating turbines have been running for acouple of years, with even larger, albeit still pretty small, windfarms in the planning stage.This thesis looks on the possibility of building large floatingwind farms in the future, specifically in the eastern most part ofthe North Sea - Skagerrak. Several different factors andstakeholders have been mapped out and important factors such aswater depth, wind speed and seabed conditions considered to createfour different future scenarios. Each scenario has been evaluatedtechnically and Levelized Cost of Energy (LCOE) has beencalculated to be able to compare the different locations.Since the technology is very new and under development, theinitial costs are high. This gives the lower LCOE of 149 €/MWh.Many new developments are however expected in the years to come,which would lower the investment cost considerably, by up to 40%according to some sources. This would lower the LCOE to under 100€/MWh.It is however also found that these investments carry many otherpositive effects, such as developing a new carbon neutraltechnology in Scandinavia which could become a big exportworldwide. The social acceptance of bottom fixed foundationoffshore (close to shore) and onshore wind power is also falling,and this would also be a big plus for floating offshore wind as itcan be built so far offshore it can't be seen from land. BothSweden and Denmark have big power plants closing in the comingdecades, nuclear power in Sweden and coal fired power plants inDenmark. These need to be replaced either by import or by newcarbon neutral power production.

This PhD thesis proposes a bottom-up approach that accurately addresses the operational flexibility embedded in each part of a multi-energy system (MES). Several models which cover the simulations from replicating domestic electrified demands to power system scheduling are proposed. More specifically, a domes-tic multi-energy consumption model is firstly developed to simulate one minute resolution energy profiles of individual dwellings with the installation of prospec-tive technologies (i.e., electric heat pumps (EHPs), electric vehicles (EVs)). After-wards, a fast linear programming (LP) unit commitment (UC) model is devel-oped with the consideration of characteristics of generators and a full set of ancil-lary services (i.e., frequency response and reserves). More importantly, the fre-quency response requirements in low inertia systems are assessed with the con-sideration of three grid frequency regulations (i.e., rate of change of frequency, Nadir and quasi-steady state). Furthermore, the UC model has integrated vari-ous flexibility contributors in MES to provide ancillary and flexibility services, which include pumped hydro storages (PHSs), interconnectors, batteries and demand side resources (i.e., individual EHPs, heat networks, electrolysers). More importantly, the fast frequency response (FFR) provision from nonsynchronous resources is implemented and the demand response application of electrolysers is taken as an example to provide FFR in the UC model. By using the integrated UC model with the consideration of flexibility services provided by resources in the MES, the advantages of multi-energy operation can be clearly identified which can be used to inform system operators and policy makers to design and operate energy systems in a more economic and environment-friendly way.

O objetivo do trabalho foi investigar o efeito da suplementação isolada de cafeína e bicarbonato de sódio sobre a contribuição dos sistemas energéticos, desempenho e reativação parassimpática após simulação de luta de taekwondo. Para tanto, a presente tese foi dividida em estudo 1, com a suplementação de cafeína e estudo 2, com a suplementação de bicarbonato de sódio. Portanto, no estudo 1, o objetivo foi investigar o efeito da suplementação de cafeína sobre a contribuição dos sistemas energéticos, desempenho e reativação parassimpática em simulação de luta de taekwondo. 10 atletas de taekwondo foram submetidos a duas sessões experimentais separadas por no mínimo de 48 horas entre elas. Nas duas visitas os atletas consumiram uma cápsula contendo cafeína (5 mg.kg-1 de massa corporal) ou placebo (celulose) uma hora antes da simulação da luta de taekwondo, composta por 3 rounds de 2 minutos com 1 minuto de intervalo entre os rounds. A ordem das sessões experimentais foi randomizada, duplo-cego e cruzada. Todas as simulações de luta foram filmadas para quantificar as ações técnico-táticas durante os rounds. Foram mensuradas a concentração de lactato, a percepção subjetiva de esforço (PSE) antes e após cada round,e a frequência cardíaca (FC) e a contribuição dos sistemas energéticos foi estimada durante a simulação de luta. Além disso, foram mensurados alguns índices da reativação parassimpática após o terceiro round. A concentração de lactato, a PSE, a FC e a contribuição dos sistemas energéticos foram comparados usando análise de variância de dois fatores (condição e tempo). Adicionalmente, os índices da reativação parassimpática foram comparados utilizando o teste t de Student entre as condições cafeína e placebo. Os principais resultados indicam que: a suplementação de cafeína aumentou a contribuição do sistema glicolítico em relação ao placebo. Porém, a cafeína não melhorou o desempenho ou alterou a PSE, a FC ou a contribuição dos sistemas oxidativo e ATP-CP quando comparados ao placebo. Adicionalmente, nenhum índice da reativação parassimpática foi afetado pela suplementação de cafeína. No estudo 2, o objetivo do estudo foi investigar o efeito da suplementação de bicarbonato de sódio sobre a contribuição dos sistemas energéticos durante a simulação de luta de taekwondo. Para tanto, foram avaliados 9 atletas de taekwondo, os quais foram submetidos a duas condições experimentais, separadas por um mínimo de 48 horas entre elas. Nas duas visitas os atletas ingeriram uma cápsula contendo 0,03 g.kg-1 da massa corporal de NaHCO3- ou placebo (carbonato de cálcio), 90 minutos antes da simulação de luta de taekwondo, composta por 3 rounds de 2 minutos com 1 minutos de intervalo entre os rounds. A ordem das sessões experimentais foi randomizada, duplo-cego e cruzada. Todas as simulações de luta foram filmadas para quantificar as ações técnico-táticas durante os rounds. Foram mensuradas a concentração de lactato, a percepção subjetiva de esforço antes e após cada round, a frequência cardíaca e a contribuição dos sistemas energéticos foram estimadas durante a simulação de luta. Além disso, foram mensurados alguns índices da reativação parassimpática após o terceiro round. A concentração de lactato, a PSE, a FC e a contribuição dos sistemas energéticos foram comparadas usando análise de variância de dois fatores (condição e tempo). Além disso, os índices da reativação parassimpática foram comparados utilizando o teste t de Student entre as condições NaHCO3 e placebo. Os principais resultados demonstraram que a suplementação de NaHCO3 aumentou a contribuição do sistema glicolítico e o tempo total de ataque em relação ao placebo. Porém, o NaHCO3 não alterou a FC, a PSE ou a contribuição dos sistemas oxidativo e ATP-CP durante a simulação de luta quando comparados ao placebo. Além disso, nenhum índice da reativação parassimpática foi afetado pela suplementação de NaHCO3 ou placebo / The aim of this study was to investigate the isolated effect of caffeine and sodium bicarbonate ingestion on performance, estimated energy system contribution and on post-exercise parasympathetic reactivation during a simulated taekwondo combat. Therefore, this thesis was divided in two studies: study 1 investigated the effect of caffeine, while study 2 investigated the effect of sodium bicarbonate. Thus, in study 1, the aim was to investigate the effect of caffeine supplementation on performance, estimated energy system contribution and on post-exercise parasympathetic reactivation during a taekwondo combat. Ten taekwondo athletes completed two experimental sessions separated by at least 48 hours. Athletes consumed a capsule containing either 5 mg?kg-1 body mass of caffeine or placebo (cellulose) one hour before the combat simulation (3 rounds of 2 min separated by 1-min passive recovery), in a double blinded, randomized, repeated-measures crossover design. All simulated combat was video recorded to quantify the time spend fighting in each round. Lactate concentration and rate of perceived exertion were measured before and after each round, while heart rate and the estimated contribution of oxidative, ATP-PCr and glycolytic systems were calculated during the combat simulation. Furthermore, parasympathetic reactivation after the combat simulation was evaluated. Lactate concentration, rate of perceived of exertion, heart rate, estimated system contributions and indices of time-motion were compared by two-way ANOVA (condition x time). All indices of parasympathetic reactivation were compared using a Student\'s t-test in both caffeine and placebo conditions. The main results showed that caffeine ingestion increased the estimated glycolytic system when compared to placebo condition. However, caffeine ingestion did not alter the rate of perceived exertion, heart rate, estimated oxidative and ATP-PCr contribution or improve the performance in relation to placebo condition. Furthermore, caffeine ingestion did not influence post-exercise parasympathetic reactivation following a taekwondo simulation when compared to placebo condition. In study 2, the main aim of the study was to investigate the effect of sodium bicarbonate ingestion on performance, estimated energy system contribution and on post-exercise parasympathetic reactivation during simulated taekwondo combat. Nine taekwondo athletes completed two experimental sessions separated by at least 48 hours. Athletes consumed 300 mg?kg-1 body mass of sodium bicarbonate or calcium bicarbonate (placebo) 90 minutes before the combat simulation (3 rounds of 2 min separated by 1-min passive recovery), in a double blinded, randomized, repeated-measures crossover design. All simulated combat was video recorded to quantify the time spent fighting in each round. Lactate concentration and rate of perceived exertion were measured before and after each round, while heart rate, estimated contribution of oxidative, ATP-PCr and glycolytic systems were calculated during the combat simulation. Furthermore, parasympathetic reactivation after the combat simulation was calculated. Lactate concentration, rate of perceived exertion, heart rate, estimated system contributions and indices of time-motion were compared by two-way ANOVA (condition x time). All indices of parasympathetic reactivation were compared using a Student\'s t-test. The main results showed that sodium bicarbonate ingestion increased the lactate concentration, estimated glycolytic contribution and total attack time when compared with placebo condition. However, sodium bicarbonate ingestion did not influence heart rate, rate of perceived exertion, estimated oxidative and ATP-PCr contribution during combat simulation compared to placebo. Furthermore, no indices of parasympathetic reactivation were different between sodium bicarbonate and placebo conditions