Is It Possible to Obtain More Energy from Solar DH Field? Interpretation of Solar DH System Data

Europe has a course to zero emissions by 2050, with a strong emphasis on energy sector. Due to climatic conditions in Latvia, district heating (DH) plays an important role in the energy sector. One of the solutions to achieve the set goals in DH is to introduce emission-free technology. Therefore, the popularity of installation of large-scale solar collector plants continues to increase in DH in Europe. The first large-scale solar collector field in the Baltic States was installed in 2019. Solar collector active area is 21 672 m2 with heat storage water tank 8000 m3. The article shows the first operation results of this system and evaluates influencing factors. The results of the analysis show that system productivity is mainly demanded by solar radiation, and the strongest correlation between these parameters were established in May. The highest correlation between ambient air temperature and produced thermal energy is reached when ambient air temperature is between 7 °C to 15 °C and production process has not been externally regulated. The temperature difference between flow and return temperatures of the heat carrier affect solar collector performance minimally and strong correlation was not observed.

Industrial Wastewaters of the Feed Industry: use of Sodium Ferrate in the Phenol Purification Process

The article presents the results of studies of the possibility of using sodium ferrate in the treatment of wastewater from organic substances on the example of phenol in the production of combined feed. This research has shown the technology of obtaining encapsulated ferrate using hexane, ethylcellulose and paraffin; it has also established the stability of encapsulated sodium ferrate in air and in an alkaline solution. Furthermore, the evaluation of the efficiency of using encapsulated sodium ferrate in the purification of the simulated solution from phenol in the technology of combined feed production.

Electronic Waste Generation Prediction in Bandung City, Indonesia

Nowadays waste electrical and electronic equipment (WEEE) generation is increasing due to the increase in the number of users and the development of electronic products. In Indonesia, there are no specific regulations about WEEE even though it is identified as hazardous and toxic waste. This study aims to predict the WEEE generation from the most used and replaced electronic products by citizens of Bandung City. The data is collected by surveying 400 families in Bandung City. Based on the survey results, there are three types of electronic products that are most used and replaced by citizens of Bandung City, which are mobile phones, laptops and televisions. The Delay Model is modified by replacing the lifespan variable with end-of-life to project the mobile phones, laptops and televisions waste generation in Bandung City. The purpose of this modification is to adjust the pattern of electronic products used in developing countries. The projection results state that Bandung City will generate 0.61 tons/day of mobile phones, 8.66 tons/day of laptops and 3.16 tons/day of televisions at the end of 2020. Based on the results of the projection, WEEE management and recycling is important which can reduce WEEE disposal and increase the economic value of WEEE.

How to Assess Policy Impact in National Energy and Climate Plans

It is the responsibility of each member state of the European Union, to prepare a national energy and climate plan and set achievable climate targets and meaningful measures and policies to achieve the targets set. Annex 4 of the Latvian National Energy and Climate Plan for 2030 (hereinafter – NECP) provides an overview of policies and measures to achieve the climate targets. The NECP does not provide information on the impact of the policies or which measures are more important and which are less crucial Similarly, the measures in Annex 4 of the NECP were not determined by industry experts but by ministry officials, therefore, it is not clear whether the proposed measures will achieve the set climate targets, a point also made by European Commission in its evaluation report on NECP. The aim of the study is to develop a tool for the early assessment of the impact of energy and climate policy measures. The study developed a methodology to pre-assess the impacts of the policies identified in the NECP, impacts were described by measures effectiveness and stage of development. With this methodology, it is possible to assess the impact of energy policies using indicators to characterize the effectiveness of the policy and the level of development. The study confirmed that both the multi-criteria analysis and composite index method can be used as methods. The results showed that high impact measures were related to the promotion of energy efficiency in buildings, but low impact measures were comprehensive horizontal measures such as measures related principle ‘energy efficiency first’ and review of energy efficiency obligation schemes. The indicators with the highest impact on sustainability rate were possible side effects and transparency of policies.

Complete Circularity in Cross-Laminated Timber Production

Many authors have discussed the paradigm shift in economy from linear to circular. Population growth and climate change caused resource scarcity are the main driving forces of shifting to circularity approach. Although consumers have been slower regarding transitioning to more sustainable economy, production companies are the ones who have felt the scarcity of resources first. In this paper we are exploring cross-laminated timber (CLT) production residue utilization possibilities for new product production and using multi-criteria analysis calculating the most promising recycling alternative from the perspective of companies working with wood as raw material. Data matrix for multi-criteria analysis was constructed from literature analysis gathering data on five criteria: (1) production costs; (2) energy consumption; (3) CO2 emissions; (4) product market price and (5) final product to wood residues ratio. Multi-criteria analysis showed that production of mycelium insulation material is the most promising alternative for CLT production residue recycling.

Investigation on Relative Heat Losses and Gains of Heating and Cooling Networks

The integration of district heating (DH) and cooling (DC) in the sustainable energy system of the future requires a significant reduction in operating temperatures. Supply temperatures below 70 °C are required for new 4th Generation DH. Main benefits are the use of low exergy heat sources and the reduction of heat losses. The reduction of heat losses is achieved by reducing the driving temperature difference between the medium pipe and the ground. The decrease of the return temperature level is limited by the consumer behaviour and the ground temperature level. As a consequence, the reduction of the supply temperature is accompanied by a reduction of the maximum transmittable heat flow. For energy efficiency and economic reasons, the relative heat losses are therefore an important design value for DH networks. The study proposes an approach to estimate the relative heat losses by using steady-state heat loss models and analyses the values for different DH generations. In particular, due to the rising of the near-surface soil temperature, the relative cold losses are also studied.

Industrial Energy Efficiency Towards Green Deal Transition. Case of Latvia.

Energy efficiency policy has been one of the European Union top priorities for decades and will continue to play a vital role in the next 10 years with the introduction of The Clean energy for all Europeans. Likewise, in Latvia energy efficiency has been given high priority; however, the energy efficiency targets for industry has lacked ambitions. This research focuses on evaluating the Latvian industrial energy efficiency policy using top-down approach and benchmarking energy intensity of Latvian industry to the average of the European Union’s. Results confirm that on average Latvian industry consumes 2.6 times more energy to produce the same amount of value added compared to the average in the European Union; however, every saved energy unit in Latvia would save twice less CO2 emissions considering already largely decarbonized energy mix. In the spotlights of the Green Deal proposed by the European Commission, much higher contribution in terms of CO2 reduction and energy efficiency will be expected from the industry. Nevertheless, energy efficiency targets for Latvian industry should be sector-specific, separately addressing CO2 intensive sectors, and non-intensive CO2 sectors with low added value.

Effect of Polysorbates on the Growth of Rhodotorula Glutinis in Oil Rich Medium

The present study has investigated the effect of oil rich medium supplementation with polysorbates Tween 20, 40 and 80, for the cultivation of red oleaginous yeast Rhodotorula glutinis. R. glutinis has been cultivated in yeast extract peptone glucose modified broth (mYPG) supplemented with 2 % of waste cooking rapeseed oil and three polysorbate types with 0.5 %, 1 %, 2%, 3 %, 4 %, 5 %, 6 %, 7 %, 8 %, 9 % and 10 % concentration each. Yeast biomass was measured by the thermogravimetric method at 105 °C each day during 7-day experiment. The oil rich medium supplementation with Tween 20, 40 and 80 at concentrations ranging from 2 % to 10 % significantly increased the biomass of R. glutinis. All three types of the studied polysorbates with 0.5 % and 1 % concentration, did not affect yeast growth and the dry biomass – results were similar to the control sample without polysorbate addition. Between the three types of polysorbates, Tween 20 was selected as the preferable for R. glutinis cultivation with an optimal concentration of 2 %. Cultivation of R. glutinis in oil rich medium with polysorbates Tween 20, 40 and 80, supplementation up to 10 % concentration did not have had an inhibitory effect on the biomass growth.

Life Cycle Carbon Footprint Assessments, Case Study of Malaysian Housing Sector

The ever-increasing concentration of Carbon footprint into the environment has drastically changed the climatic conditions. Among many anthropogenic activities, the housing sector remains one of the major contributors. However, a complete assessment of these environmental impacts throughout the life cycle still remains an area of concern. Most of the study does not assess the impacts by each phase of lifecycle. The current work presents a complete approach for carbon footprint assessment including planning, construction, operational, maintenance and dismantling & dispose-off phase. Life Cycle Assessment (LCA) with boundary limitations of ‘cradle to grave’ was adopted. Thirteen housing units were selected as case study. These included detached, semi-detached and terraced types of construction. Selected units were developed in a virtual environment using Building Information Modeling (BIM). The study observed the average contribution range from 1.48 tons-CO2/yr to 2.85 tons-CO2/yr. On individual basis, the execution phase dominated the five phases with almost 43 %. The operational phase shared 39 % followed by maintenance (15 %), dismantling & dispose-off (1.8 %) and planning at the last (1.5 %). The categorization of environmental impact into embodied and operational carbon footprint observed the embodied part in dominance. A strong positive relationship between the area of housing units and resulting carbon impact was also observed. The work presents one of few environmental studies for a tropical housing sector assessing complete life cycle. The study provides a vital guideline to the designers for ensuring a sustainable environment by assessing and opting less carbon intensive options at early stage of planning and design.

Ni Underlayer Effect for the Structure Development and Visible Light Photocatalytic Efficiency of Carbon-Doped TiO2 Film

Photocatalytic treatment of contaminated aqueous solutions makes use of the specific interaction between photocatalysts and ultra-violet or visible light irradiation. This method belongs to the wider class of Advanced Oxidation Processes that generates reactive oxygen species (peroxides, superoxide, hydroxyl radical, singlet oxygen, etc.) and uses them for the non-selective oxidation of various organic and inorganic compounds. In THE current study magnetron sputtering technique was used to deposit carbon-doped TiO2 films which are known to have significant photocatalytic activity in the visible light spectra and can be used for the neutralisation of contaminated solutions. Structural properties of the as-deposited films were analysed by XRD, XPS and AFM techniques, whereas their visible light photocatalytic activity was estimated by analysing Rhodamine B solution bleaching kinetics. When carbon-doped TiO2 photocatalysts were formed on borosilicate glass XRD analysis showed that they consisted of mixed phase (rutile-anatase) TiO2 where both phases contributed by similar parts. However, when the same deposition procedure was used to deposit carbon-doped TiO2 films on glass covered by Ni layer, formation of metastable anatase phase was enhanced. Estimation of visible light photocatalytic activity of the films revealed that Ni underlayer had positive effect for the efficiency of Rhodamine B solution bleaching and it could be beneficial for the practical wastewater treatment systems. It was suggested that observed improvement was mainly achieved due to the structural changes of TiO2 crystal phase, but other mechanisms like prevention of impurity diffusion from the glass substrate to the carbon-doped TiO2 film, or positive Ni doping effect could not be excluded completely.