• Energy Research

Abstract The effects of disasters on communities is a critical issue to be considered in terms of growing exposure of infrastructures to natural hazards. The significant role of the infrastructure systems – and thus their interconnections – is a key for the current urbanization development expected to increase within the next years. Thus, the role of infrastructures should guarantee the support of urban life standards to guarantee public welfare. This aim can only be designed with an enhanced level of infrastructural resilience within the field of crisis management. The concept of infrastructure resilience is normally linked with the ability to cope with severe disruptions, guaranteeing a minimal level of a specific function of infrastructure itself. This framework provides a useful tool to enable stakeholders to effectively assess resilience strategies that are a key factor for building a resilient infrastructures. Considering this, the aim of this research is to present a resilience evaluation tool addressed to evaluate potential scenarios for enhancing the resilience of a specific infrastructure network and to further identify the most sensitivite assets of that critical infrastructure network. The case of a real system was examined by the application of probabilistic methods applied to infrastructure network to generate statistical data for the calculation of the district heating (DH) pipeline network resilience of a municipality in Latvia. The study clarifies how resilient the district heating system is to a specific hazard and what could be the effect of specific investment scenarios aimed to enhance resilience. It will also identifies the most resilient assets of the DH network system and thus determine the main features of a DH systems that are important to ensure overall infrastructure resilience.

Abstract New seaweed cultivation laboratory was developed and primary laboratory bench was tested if the conditions are relevant for seaweed cultivation. Simple experiment was carried out using Ulva intestinalis as test organism. Different nutrient levels were provided to see, which amount of nutrient is the best for cultivation of U. intestinalis. Experiment results showed that best growth rate for Ulva intestinalis was on concentration 2 ml L –1 where growth rate reached on average 7.13 ± 3.44% per day. Higher nutrient amounts slow down algae growth.

Abstract Life cycle costs of co-digestion plant of cattle farm manure and locally available freshwater macrophyte C. demersum, marine brown algae F. vesiculosus, and marine green algae U. intestinalis; ratio 5:1) are analysed based on Latvian climatic and economic conditions. Biomass collection from nature and pre-treatment of biomass, biogas production, biogas treatment and utilization in combined heat and power plant are included in the boundaries. The weak points of scenarios are large capital investments, electricity sale price (and the application of feed-in tariff). As naturally grown algae and macrophytes are used, they are also sensitive to weather conditions each year as available amounts of biomass might change and decrease. Net Present Value is positive only for C. demersum with Internal Rate of Return of –14 % and Discounted Payback Period of 11 years.

AbstractThe 2005 UN Hyogo Declaration introduced the concept of resilience in the field of disaster risk reduction (DRR) unifying environmental sustainability and civil protection concepts. Crucial in this new approach is the development of a new quantitative adaptive strategy, which starting from the risk analysis of a territory, aims at strengthening a symbiotic and adaptive relationship between human communities and their surrounds. This paradigmatic shift needs new analytical and measuring tools in order to describe, evaluate and develop sustainable DRR strategies. Traditional cartographic tools, such as hazard, vulnerability, or risk maps, cannot appropriately represent the overall resilience of a territory (inclusive of its social and environmental dimensions). This article proposes a methodological approach to map such community resilience by assessing energy and resource consumption to maintain the stability of the social-ecological system. Starting from the identification of the complex relations between socioeconomic processes and disasters, this method computes a resilience score or index, integrating hazard and vulnerability factors with emergency management actions (e.g. community planning, mitigation and disaster response capabilities). Such index will enable, inter-alia, the drawing of maps of resilience, necessary to planners and policy makers to assess the effects and sustainability of different DRR strategies and policies.

Urban growth needs large cities, and the current emphasis on landscape preservation makes using underground spaces both an opportunity and a significant necessity. However, underground construction techniques significantly impact the sustainability of the built environment, including infrastructure systems and their entire supply chains. Nowadays, there is a shortage of quantitative methodologies to assess and measure the sustainability of underground building processes that effectively integrate the three pillars of sustainability (environmental, social, and economic). Thus, this study aims to solve the abovementioned issues by explaining how to incorporate sustainability goals into geotechnical projects to address measure-driven strategies and eco-design-based solutions appropriately. This study illustrates a novel methodology based on the Life Cycle Thinking approach, with a particular emphasis on geotechnical ground improvement techniques. Specifically, the suggested method incorporates the concept of the EU Taxonomy, following the EU Green Deal, with the Envision framework to guide decision-makers toward a more sustainable, resilient, and equitable infrastructure design. In addition, incorporating a cradleto-grave Life Cycle Assessment (LCA) into the suggested methodological approach will improve the quantitative estimation of the performance of construction processes. The definition of the proposed method will provide the guidelines to systematically assess the sustainability of geotechnical infrastructures to allow further the selection of an optimal solution to reduce their impact from an environmental, social, and economic point of view.

Abstract Microalgae cultivation at biogas plants creates joint benefits for using liquid digestate and exhaust gas from the CHP unit as nutrient and carbon sources for microalgae growing. This circular approach increases biogas production’s sustainability towards a bioeconomy and zero-waste perspective. This study aims to evaluate the potential environmental impacts in connection to a novel microalgae growing technology named Stacked Modular Open Raceway Pond (SMORP) as a side-stream process coupled with centrate and exhaust gases from a biogas plant. A comparative LCA according to ISO 14044 is performed between the innovative SMORP concept at the pilot level and a hypothetical scaled-up system. Primary data for the inventory are directly gathered from the microalgae growing test performed at the biosystems laboratory of the Institute of Energy Systems and Environment of the Riga Technical University. Secondary data are collected from literature mostly in terms of mass and energy balances considering the SMORP pilot project design. The results of the LCA include the main findings both at mid and endpoint categories according to the IMPACT 2002+ method. In addition, a sensitivity analysis for several different parameters has been investigated. Results show the feasibility of the coupled system and the possibility of having benefits once the system is scaled up. Nevertheless, the results show a critical dependency of the environmental performance on the local conditions, potentially affecting too high cultivation costs.

AbstractThis study presents a comprehensive analysis of costs and benefits of technologies based on cold plasma for the removal of sulfur and nitrogen oxides of flue gases. Assessment is based on welfare economics and seeks to include all relevant costs and benefits to evaluate the net social benefit of a project. A plasma unit installed in a CHP plant was used as the case study for this study. Results obtained from the study showed that the use of plasma technology is not financially viable unless all economic, social and environmental costs and benefits for all parties affected by the project are included. Compared to alternative flue gas treatment technologies, plasma proved to be more economically attractive if capital expenditures and operating costs were taken into account.

AbstractSeaweed biomass is washed ashore on beaches causing recreational problems for local inhabitants and tourists. The management of marine waste in Latvia is not well developed. Brown algae Fucus vesiculosus is one of the most abundant seaweeds in Latvia. The chemical composition of brown algae Fucus vesiculosus, collected from the Gulf of Riga, was evaluated. Algae contain higher amounts of both macroelements (490 – 21500ppm; P, K, Ca, Mg, Na, Fe, Mn) and trace elements (0.11 – 930ppm; Zn, Cu, Cr, Pb, Sr, As, Cd, Se) than terrestrial plants. The obtained composition was used to describe the potential uses of seaweed. Food, pharmacy and bioenergy were considered as potentially the best sectors for macroalgae use. Due to high levels of heavy metals in seaweed, it is not recommended to use F. vesiculosus from Gulf of Riga as a food. The best potential use is found to be using it as biomass feed to obtain biogas.