Lunar ISRU Energy Storage and Electricity Generation

The survival of the astronauts and their equipment is the priority for any long-term exploration mission to the Moon. The provision of energy during the long lunar nights is a critical part of these missions. Several approaches have recently been considered to store and provide energy on the Moon by means of ISRU (In-Situ Resource Utilisation). We present a review of the energy requirements for a long mission scenario, and a trade-off analysis of the potentially suitable technologies for an ISRU-based system able to store heat and generate electricity. The most promising combinations of technologies are presented.Peer ReviewedPostprint (published version

The Role of Innovation in Industry Product Deployment: Developing Thermal Energy Storage for Concentrated Solar Power

Industries with fast‐developing technologies and knowledge‐intensive business services rely on the development of scientific knowledge for their growth. This is also true in the renewable energy industry such as in concentrating solar power (CSP) plants, which have undergone intense development and expansion in the last two decades. Yet knowledge generation is not sufficient; its dissemination and internalization by the industry is indispensable for new product development. This paper contributes to providing empirical evidence on the known link between knowledge development and firm growth. In 10 years the cost of electricity produced through CSP has decreased five‐fold. This decrease has only been possible due to innovation projects developed through a complex network of research and development (R&D) collaborations and intense investment, both public and (to a greater extent) private. The development and construction of pilot plants and demonstration facilities are shown to be key in maturing innovations for commercialization. This is an example of how the private sector is contributing to the decarbonisation of our energy system, contributing to the objectives of climate change mitigation.Funding: The work was partially funded by the by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018‐093849‐B‐C31‐ MCIU/AEI/FEDER, UE) and by the Ministerio de Ciencia, Innovación y Universidades ‐ Agencia Estatal de Investigación (AEI) (RED2018‐102431‐T). Abengoa thanks the Spanish Ministry of Science and Innovation that has allowed us to finance R&D in CSP: CDTI (IDI‐20090402, ITC‐ 20111050, ConSOLida CENIT 2008‐1005, CDTI IDI‐20090393, ITC‐20131017); and European Commission: H2020 programme (H2020‐LCE‐2015 Sun‐to Liquid, H2020‐LCE‐2015 Solpart). We thank the partners of the consortium who have allowed these developments and thank all members of the Abengoa CSP department Acknowledgments: Dr. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group GREiA (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme. We would like to thank the partners of the consortium who have allowed these developments and thank all members of the Abengoa CSP department

Advanced Concrete Steam Accumulation Tanks for Energy Storage for Solar Thermal Electricity

Steam accumulation is one of the most effective ways of thermal energy storage (TES) for the solar thermal energy (STE) industry. However, the steam accumulator concept is penalized by a bad relationship between the volume and the energy stored; moreover, its discharge process shows a decline in pressure, failing to reach nominal conditions in the turbine. From the economic point of view, between 60% and 70% of the cost of a steam accumulator TES is that of the pressure vessel tanks (defined as US$/kWhth). Since the current trend is based on increasing hours of storage in order to improve dispatchability levels in solar plants, the possibility of cost reduction is directly related to the cost of the material of pressure vessels, which is a market price. Therefore, in the present paper, a new design for steam accumulation is presented, focusing on innovative materials developed specifically for this purpose: two special concretes that compose the accumulation tank wall. Study of dosages, selection of materials and, finally, scale up on-field tests for their proper integration, fabrication and construction in prototype are the pillars of this new steam accumulation tank. Establishing clear and precise requirements and instructions for successful tank construction is necessary due to the highly sensitive and variable nature of those new concrete formulations.The research leading to these results has received funding from CDTI in the project Innterconecta Thesto (ITC-20111050). The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31—MCIU/AEI/FEDER, UE) and by the Ministerio de Ciencia, Innovación y Universidades—Agencia Estatal de Investigación (AEI) (RED2018-102431-T). This work is partially supported by ICREA under the ICREA Academia programme. Acknowledgments The authors would like to thank all the Chirivo Construcciones, Hormigones Aznalcóllar, Elabora, Azcatec, Next Force Engineering, Universidad de Granada, Aidico, Centro Andaluz de Metrología, AICIA and Abengoa teams involved in Solúcar Platform during prototype construction and start-up. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group GREiA (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia

Preparation of binary nanofluid with heat transfer additives by particle surface functionalisation

Current binary nanofluid synthesis methods with heat transfer additives lack an understanding of the chemistry of the nanoparticle-additive-base fluid interaction, which plays a significant role in the adsorption of the surfactant on the nanoparticle surface. Consequently, this leads to the formation of aggregates within the nanofluid after a couple of days, affecting the stability of the colloidal suspension. Here, a lithium bromide-alumina salt-based nanofluid is proposed following a newly developed synthesis method including particle surface functionalisation. The new procedure developed allows the initial preparation of the nanoparticles with the surfactant as the first step (surface functionalisation) and then the preparation of the base fluid with a dispersion stabilising agent (Gum Arabic) separately. This is then followed by the dispersion of the prepared alumina nanoparticles into the base fluid, by stirring and ultrasonication to produce the final nanofluid, lithium bromide-water (LiBr-H2O)-alumina nanofluid. Until now, proper procedures have not been reported for the nanofluid synthesis combining surfactant and dispersant and the chemistry of nanoparticles-surfactant-base fluid interaction, which was thoroughly investigated in the new approach. The fluid prepared by both the conventional and new procedures was characterised and analysed simultaneously. A thermal conductivity enhancement of 3% was achieved by using the surface functionalisation method, with greater particle concentration distribution (number of particles in suspension) of 22.7% over the conventional procedure. It also achieved a 5% decrease in dynamic viscosity. On the other hand, a Mouromtseff number value between 0.7 and 1.8 was obtained for the fluid at 293 K and 373 K temperature range, indicating a strong heat transfer capability. It was apparent from the particle size and concentration distribution analysis conducted that this procedure produced a more stable nanofluid with a high distribution of nanoparticles within the fluid. This allows high improvement of thermal properties of the fluid

The effects of ejector adiabatic absorber on heat and mass transfer of binary nanofluid with heat transfer additives

This paper presents experimental results on the study of the effects of ejector adiabatic absorber on heat and mass transfer of binary nanofluid with heat transfer additives (2-ethyl-1-hexanol and gum Arabic). In this case, H2O/lithium bromide-alumina nanofluid was suggested due to a growing interest in absorption heat transfer working fluid for solar energy application. An experimental setup — ejector test rig — was designed to study the absorption, heat, and mass transfer rate as a result of refrigerant vapour mass flow entrained by the ejector adiabatic absorber. The study was carried out at different solution mass flowrate (0.051 to 0.17 kg/s) with three prepared sample solutions, which include pure LiBr solution, LiBr-Alumina nanofluid without heat transfer additives, and LiBr-Alumina nanofluid with heat transfer additives. The absorption rate, mass transfer coefficient, heat transfer rate, and heat transfer coefficient for the three samples were reported. On the other hand, the percentage enhancements for all the parameters — at a suitable flow rate of 0.085 kg/s — due to the addition of alumina without and with heat transfer additives were recorded. The absorption rate enhancements were 25% and 96%, the enhancement rates of mass transfer coefficient recorded were 20% and 82%, the heat transfer rate enhancements were 85% and 183%, and the heat transfer coefficient enhancements obtained were 72% and 156% with addition of alumina nanoparticles only and alumina nanoparticles with heat transfer additives respectively. Material mass balance analysis suggests that mass inflow in the ejector equals to the mass outflow from the ejector, indicating a complete absorption of the entrained refrigerant vapour beyond which falling film absorption can occur due to concentration. This article also presents experimental evidence of the capability of ejector as strong adiabatic absorber, heat, and mass transfer component, which were earlier reported using numerical model

Mass flux at ignition in reduced pressure environments

Ignition of solid combustible materials can occur at atmospheric pressures lower than standard either in high altitude environments or inside pressurized vehicles such as aircraft and spacecraft. NASA’s latest space exploration vehicles have a cabin atmosphere of reduced pressure and increased oxygen concentration. Recent piloted ignition experiments indicate that ignition times are reduced under these environmental conditions compared to normal atmospheric conditions, suggesting that the critical mass flux at ignition may also be reduced. Both effects may result in an increased fire risk of combustible solid materials in reduced pressure environments that warrant further investigation. As a result, a series of experiments are conducted to explicitly measure fuel mass flux at ignition and ignition delay time as a function of ambient pressure for the piloted ignition of PMMA under external radiant heating. Experimental findings reveal that ignition time and the fuel mass flux at ignition decrease when ambient pressure is lowered, proving with the latter what earlier authors had inferred. It is concluded that the reduced pressure environment results in smaller convective heat losses from the heated material to the surroundings, allowing for the material to heat more rapidly and pyrolyze faster. It is also proposed that a lower mass flux of volatiles is required to reach the lean flammability limit of the gases near the pilot at reduced pressures, due mainly to a reduced oxygen concentration, an enlarged boundary layer, and a thicker fuel species profile

Lunar ISRU energy storage and electricity generation

Fifty years after the first human step on the Moon, many challenges for its exploration have yet to be overcome. Among them, the survival of the crew and/or lunar assets during the lunar night is mandatory for long duration missions. The environmental conditions of the lunar surface and its day-night cycle, with long periods of darkness, make the provision of energy a critical challenge. Several approaches have recently been considered to store and provide energy in the surface of the Moon by means of ISRU (In-Situ Resource Utilisation)Postprint (updated version