Investment Payback Time Research Articles

Energetic and economic advantages of energy communities: a case study referred to a southern Italian town

Energy Districts and Communities are at the heart of EU programs. Nevertheless, several challenges are encountered when bringing into fruition. Their convenience is not fully understood on a small scale, due to the complexity of the start-up practices, which make them more suitable for commercial or industrial companies.In this scenario the present study arises, aimed at pointing out to small communities, at condominium scale, the economic benefits, in terms of Net Present Value (NPV), deriving from the adoption of the new community plant configurations. Such indicator gives a glance of the total cost, both investment and functioning ones, to be sustained during the plant life, together with the enjoyed benefits. Particularly the investment cost is presently a big obstacle to the spread of renewable energy systems whereas the high operative cost of conventional plants is less adequately considered.In this frame, through the paper the satisfaction of the electricity needs of the users of a building, sited in Reggio Calabria (Italy), when their plant configurations turn from single grid-connected into community is analyzed using 2024 tariffs. From the study the economic advantages of the community result, pointing out an NPV increase (€ 3,798), with a consequent reduction of the investment pay-back time for most users. The benefit increases (€ 24,918) when an energy intensive user joins the community. The study also considers a plant configuration equipped with storage, pointing out the reduced grid exchanges: a lower injection of 5.6 MWh and a lower withdrawal of 6.9 MWh. Concerning NPV, despite the batteries cost and their replacement every 10 years, only low reductions are observed, thanks to the great saving obtained by stored energy, that make the investment convenient. In the future the study will be enriched with the analysis of plant configurations that consider aggregation among adjacent buildings.

ROGER: A method for determining the geothermal potential in urban areas

Shallow geothermal energy is increasingly adopted for heating and cooling purposes because of the short pay-back time of initial installation investments. As a result, a relevant concentration of Ground Heat Exchangers is being experienced in urban areas. Planning issues thus arise to manage interferences and optimize the use of underground heat resources without depletion, harm to the environment nor efficiency losses on heat pumps or plant oversizing. This study provides a rational approach to optimise geothermal resources based on the use of Geographic Information Systems and transient 3D Thermo-Hydro numerical models. An optimised semi-analytical formula for the assessment of Borehole Heat Exchangers geothermal potential in hydrodynamic conditions is developed through a parametric numerical study. The long-term performances of BHE subjected to groundwater velocity in the range of 0 to 1 m/day were analysed with multiple aquifer thermal parameters. This analytical expression allows a fast and accurate assessment of the potential even in large areas without leading to excessively conservative evaluations. This may serve designers in the preliminary sizing of installations and city planners in the development of appropriate policies for the promotion and management of shallow geothermal resources. An example of the application to the central district of the city of Turin (Italy) is also shown.

Analysis of the Economic Soundness and Viability of Migrating from Net Billing to Net Metering Using Energy Cooperatives

In the European Union, increasing attention is already being paid not only to the development of renewable energy sources, but also to the establishment of solutions to achieve local energy self-sufficiency while increasing the role of citizens in managing the energy they generate. This approach is expected both to have a positive impact on the environment and the reduction of greenhouse gas emissions, and to enhance energy security—both in economic and civic terms by, i.a., combating energy poverty. The development of local energy communities promoted in the EU is supported i.a. by energy cooperatives. These contribute to the efficient harnessing of renewable energy potential in rural and urban-rural areas, and have been developing in Poland for several years now. In their previous studies, the authors of this research paper attempted to verify the generation (number, type and capacity of installed sources) and consumption (energy demand) configurations in which an energy cooperative would be a viable solution for prosumers who might establish it. However, over the past few years, the conditions for prosumers and the method of their accounting with the electricity seller have changed radically in Poland (shift from net metering to net billing). This situation has opened up space for further research and encouraged the authors to revisit the problem of analyzing the viability of establishing energy cooperatives in relation to the rules of operation of individual prosumers. This research was carried out for three scenarios, and the horizon of the analyses conducted and described extends to 2045. The comparative analysis included energy consumers without their own generation sources, prosumers with a photovoltaic generation installation covered by the net billing model, as well as a scenario involving prosumers’ cooperation within an energy cooperative, which by law is settled in the net metering model. Conclusions from the research and simulations made it possible to confirm the claim that, despite changes in the rules of prosumer billing, developing energy independence in the energy community formula results in a significant reduction in the cost of purchasing electricity (even several times lower purchase costs in the timeframe analyzed) and can lead to a reduction in the payback time of investments in generation sources even by a factor of two. The results presented in this research paper open up space for further research. The outcomes allow us to assume that energy cooperatives—in the organizational and institutional model in Poland—are a good tool for reducing the phenomenon of energy poverty on a local scale.

Economic analysis of hybrid solar-wind power system for application in Heipang community

Economic feasibility is one of the major criteria for selecting energy options for application in any location. One of the main drawbacks of renewable energy technology is its initial cost of investment which results in high energy tariffs making it unaffordable for low-income earners. The cost of renewable energy depends on many factors such as the potential of the renewable resources of the site and government policies on renewable energy technology. This paper aimed to determine the annualized cost of a designed hybrid solar-wind power system for the Heipang community to meet a load demand of 158.3kW and the sensitivity analysis of bank loan interest rate, inflation rate, day of autonomy, depth of battery discharge, and wind turbine rated velocity on the investment payback time. The cost of the components of the designed system was obtained from vendors and a techno-economic analysis was done using MATLAB software. Results show that the annualized cost of the hybrid solar-wind power system is ₦ 52,268,266.97, with battery, solar, and wind power systems taking 85%, 8%, and 7% of the total annualized cost respectively, and Levelized cost of energy ₦ 154.53/kWh. The analysis further shows that for ₦ 185.00, N 160.00, and ₦ 127.00 per kWh cost of energy at a 19% inflation rate and 20% bank interest rate, the investment payback times are 8.3, 9.5 and 11.9 years respectively, and 9.8, 11.4 and 14.3 years respectively. Information from this work may help policy-makers and would-be investors make informed decisions on renewable energy technology investment.

Experimental and techno-economic analysis of solar-assisted heat pump drying of biomass

Drying enhances the attributes of biomass, such as storability and heating value. In regions with low solar radiation, solar drying has demonstrated limited economic viability. Hybrid systems, combining solar drying with a stable heat source such as a heat pump, present an opportunity to improve drying performance and achieve cost savings, especially with time-variable electricity pricing. To quantify this potential, we constructed an experimental drying system in Finland, incorporating an air-source heat pump and solar thermal collectors for drying woody biomass. Experimental work, consisting of 316 h of operation in varied conditions, evaluated the performance of the hybrid drying system. Subsequently, we developed data-driven models to estimate drying rates and power consumption in both hybrid and solar operation modes. Finally, these models were integrated into a techno-economic optimization model to assess the economic feasibility of the concept through hourly simulations. Hybrid drying experiments resulted in a significantly improved average drying rate (33.0 kg/h ± 5.4 kg/h) compared to solar drying (9.0 kg/h ± 3.2 kg/h) with a 45% increase in specific electricity consumption. The experimental work also revealed limited operating flexibility in colder temperatures due to an exponentially increasing preheating time (up to 4.2 h at 0 °C). With techno-economic modelling, the simulations yielded a simple payback time of 7.5 years for a commercial-scale drying system without investment subsidies. Applying an optimized operating strategy, system operation shifted on average from hybrid mode (96–33%) to solar mode (3–36%) and inactive state (1–31%) with an increased electricity price level, highlighting the need for advanced operation planning. Commercial deployment should prioritize use cases with high value increase through drying or obtaining compensation from avoided biogenic CO2 emissions through drying, as these two parameters were shown to have the greatest impact on the investment payback time.

Life cycle energy, economic, and environmental analysis for the direct-expansion photovoltaic-thermal heat pump system in China

The photovoltaic-thermal heat pump system, which integrates multiple energy technologies, can meet the building's diverse energy needs. This study evaluates the energy, economic, and environmental performance of a direct-expansion photovoltaic-thermal heat pump system for domestic hot water supply through a life cycle approach. The annual thermal and electrical outputs are estimated. On this basis, economic analysis is conducted with indicators of life cycle cost, levelized cost of heat, and investment payback time. Moreover, a detailed life cycle assessment is performed to evaluate the environmental impact, following three methods: cumulative energy demand, IPCC 2021 global warming potential, and ReCiPe 2016 Endpoint. Results show that the proposed system is highly effective, with a 9.67% increase in annual electricity output over traditional photovoltaic systems and a self-sufficient rate of 88.21%. The system also has a significantly lower environmental impact than conventional heating systems, with a life cycle environmental impact of only 3–5% compared to electric boilers. The environmental payback time ranges from 0.33 to 5.18 years, according to the three methods used in the study, which is shorter than the investment payback time of 2.49–5.21 years, suggesting the need for cost reduction for future promotion. Moreover, electricity consumption during the operation stage accounts for 32–52% of the total environmental impacts. Thus, decarbonization of the power grid and improvements in system efficiency can significantly reduce the system's environmental footprint. Overall, the photovoltaic-thermal heat pump system is an intriguing strategy for building energy conservation, offering high energy efficiency, acceptable costs, and low environmental impact.

Quantifying impacts and benefits of advanced remote monitoring solutions for the operation of mini grids in sub-Saharan Africa

As of 2022, 675 million people do not have access to electricity globally. The large majority of this underserved population lives in Sub-Saharan Africa. Mini grids systems play a central role to close this energy access gap. The adoption of latest technologies such as remote monitoring solutions can contribute to strengthen mini grids business case by improving their operation, maintenance and performance. In this study we present the latest trends, opportunities and challenges of remote monitoring solutions for mini grids and we illustrate the potential of this technology in optimizing mini grids operations, making the case for wider adoption in the sector. The analysis is developed assessing primary data collected from seven mini grids developers, covering 49 photovoltaic autonomous hybrid rural mini-grids across seven sub-Saharan Africa countries. To better understand the advantages of remote monitoring solutions we present a classification based on their related benefits compared to manual/local monitoring options. Orientation toward the adoption of remote monitoring solutions by mini grids developers highlights the advantages from a market and from the operational and maintenance perspectives. Through a cost-benefit analysis of remote monitoring solutions, we show that can have a positive impact on mini grids operations, leading to an overall operational expenditures reductions of up to 17 %, with an investment payback time as short as 1 year. Finally, we provide an estimation of operational costs savings at country level by using remote monitoring solutions in future rural electrification efforts.

Assessment of the wind energy potential and economic viability of selected sites along Nigeria’s coastal and offshore locations

Wind energy is a promising sector in the power generation industry because it is renewable and globally available. In this research work, the wind energy potential and the economic viability of using wind turbines to generate electricity in some selected sites along Nigeria’s coastline and offshore locations were evaluated. Using the statistical two-parameter Weibull probability density function method, wind speed data retrieved from an indigenous oceanography company and global information system (GIS) were analyzed for wind energy harvest. The energy output, unit cost of electricity generated by three commercially available wind turbine models (3 MW, 4 MW, and 6 MW), net present value (NPV), and payback period were evaluated. Levelized cost of electricity (LCOE) sensitivity to the discount rate, foundation cost, and turbine lifespan were also examined. The findings from the study showed that the offshore sites have four times greater wind power potential than the coastal sites. The offshore sites can be categorized as “class IIIb” wind sites, making the locations suitable for wind energy harvest. The techno-economic analysis showed that the net gains from investing in a 60-MW wind farm in the region can be as high as $62,000,000.00, while the project payback time can be as low as 5.74 years. Two of the offshore sites are recommended for the development of an offshore wind farm in the country because of their relatively low LCOE (0.04 $/kWh), higher NPV, and lower investment payback time. The Vesta-117 model wind turbine is the most suitable wind turbine system and recommended for use in the region because of its low cut-in speed (3 m/s). Sensitivity analysis showed that the LCOE of offshore-01 was reduced by 31% when the lifespan of the V117 turbine was increased from 20 to 25 years. The results also showed that reductions in the discount rate and foundation cost positively affect the LCOE.

Production of Trichoderma harzianum K179 bioagent for maize diseases control: complete laboratory stage bioprocess development.

In order to be competitive on the market, the production of biopreparations needs to be optimized, modeled and assessed in the early stages of its development. The aim of this paper was to optimize medium for the production of Trichoderma harzianum K179 biocontrol agent, to analyze its kinetics at enlarged laboratory scale and finally economic analysis of the production of this high-value product through simulation modelling. The results showed that the bioprocess of T. harzianum K179 bioagent production in a laboratory bioreactor on the medium with optimal composition (dextrose 10 g l-1, soy flour 6.87 g l-1, K2HPO4 1.51 g l-1, KCl 0.5 g l-1 and MgSO4 x 7H2O 0.5 g l-1), at stirring speed of 1.75 x g and aeration intensity of 1.5 vvm, can be shortened from 96 h to 36 h. The results of bioprocess economic analysis showed that with a 25-year project lifetime and investment payback time of 7.58 years, this project represents an economically viable system. Complete analysis of the bioprocess of Trichoderma harzianum K179 biocontrol agent production showed that the biologically produced preparation can be competitive on the market with synthetic preparations.

On Net Energy Metering X: Optimal Prosumer Decisions, Social Welfare, and Cross-Subsidies

We introduce NEM X, an inclusive retail tariff model that captures features of existing net energy metering (NEM) policies. It is shown that the optimal prosumer decision under NEM X obeys by a two-threshold policy. The threshold policy yields three household consumption modes: (a) the net-consuming mode where the prosumer consumes more than its behind-the-meter distributed energy resource (DER) production when the DER production is below a predetermined lower threshold, (b) the net-producing mode where the prosumer consumes less than its DER production when the DER production is above a predetermined upper threshold, and (c) the net-zero energy mode where the prosumer’s consumption matches its DER generation when its DER production is between the lower and upper thresholds. Both the thresholds are obtained in closed-form and computed apriori. Next, we analyze the regulator’s rate-setting process that determines NEM X parameters such as retail/sell rates, fixed charges, and price differentials in time-of-use tariffs’ on and off-peak periods. A stochastic Ramsey pricing program that maximizes social welfare subject to the revenue break-even constraint for the regulated utility is formulated. Performance of several NEM X policies is evaluated using real and synthetic data to illuminate impacts of NEM policy designs on social welfare, cross-subsidies of prosumers by consumers, and payback time of DER investments that affect long-run DER adoptions.

Innovative Data-Driven Energy Services and Business Models in the Domestic Building Sector

The market of energy services for the residential sector in Europe is very limited at present. Various reasons can be argued such as the high transaction costs in a highly fragmented market and the low energy consumption per dwelling. The rather long payback time for investments render Energy Services Companies’ (ESCOs) services financially unattractive for many ESCOs and building residents, thus hindering a large potential of energy savings in a sector that is responsible of almost half of Europe’s energy consumption. If the ambitious 2030 and 2050’s decarbonisation targets are to be met, the EU’s residential sector must be part of the solution. This paper offers insights about novel ESCO business models based on intensive data-driven Artificial Intelligence algorithms and analytics that enable the deployment of smart energy services in the domestic sector under a Pay-for-Performance (P4P) approach. The combination of different sources of energy efficiency services and the optimal participation of domestic consumers in aggregated demand response (DR) schemes open the door to new revenue streams for energy service providers and building residents and reduce the hitherto long payback periods of ESCOs services in the sector. Innovative business models for ESCOs and demand flexibility Aggregators are thoroughly described. Especially customised Performance Measurement and Verification protocols enable fair and transparent P4P ESCO contracts. The new human-centric energy and non-energy services increase the energy consumption awareness of building users and deploy behavioural and automated responses to both environmental and market signals to maximise the economic benefit for both energy service providers and consumers, always respecting data protection rules and the consumers’ comfort preferences. The new hybrid business models of P4P energy services make traditional EPC more attractive to energy service providers, with low cost data collection and treatment systems to bring payback periods below 10 years in the residential building sector.

Analysis of the Impact of the Level of Self-Consumption of Electricity from a Prosumer Photovoltaic Installation on Its Profitability under Different Energy Billing Scenarios in Poland

Renewable Energy Sources (RES) have been gaining popularity on a continuous basis and the current global political situation is only accelerating energy transformation in many countries. Objectives related to environmental protection and use of RES set by different countries all over the world as well as the European Union (EU) are becoming priorities. In Poland, after years of a boom in photovoltaic (PV) installations, the Renewable Energy Sources Act has been amended, resulting in a change to the billing system for electricity produced by individual prosumers. The change in the billing method, also in pursuance to the provisions of EU laws, has contributed to the inhibition of the PV installation market for fear of energy prices and investment payback time. In this paper, by using the Net Present Value (NPV) method, three mechanisms of billing of electricity from prosumer micro-installations—based on the net-metering principle and net-billing principle (using monthly and hourly prices)—have been analysed. Particular attention has also been paid to the aspects of electricity self-consumption and energy storages, which play a significant role in the economy of PV installations in the net-billing system.

Drivers to energy efficiency measures in recycled paper and pulp industry in India: An interpretive structural modelling-based framework

Energy efficiency can contribute significantly to the competitiveness of Paper and pulp industry on account of it being energy intensive. Certain drivers that support implementation of energy efficiency measures are of interest to the decision makers. The present work studies these drivers to energy efficiency in the recycled fibre-based Paper and Pulp industry in India. It pinpoints the drivers that are relevant and important, using interpretive structural modelling. The hierarchical model brings out presence of a dedicated energy manager, skills and motivation of employees and investment costs and payback time to be the most important drivers. The drivers have been classified based on their driving power and dependence power using “cross impact matrix multiplication applied to a classification” (MICMAC) analysis. Top management commitment and investment costs and payback time emerge as independent drivers having strong driving power but weak dependence power. Utilizing these drivers appropriately could help organizational efforts towards energy efficiency significantly.

Multivariant Analysis of Photovoltaic Performance with Consideration of Self-Consumption

The presented work contains the comparison of a different photovoltaic system approach, in terms of monthly energy production profiles, with detailed user needs profiles. Two types of investors were taken into account—a company where the yearly energy consumption exceeded 50 MWh and a standard household where the yearly energy consumption was around 6 MWh. Moreover, two different scenarios were considered; the first one was focused on the maximization of the energy production during a year by choosing optimal azimuth and tilt angles, whereas the second PV system was based on the East–West azimuth angles, which usually enables one to have better energy self-consumption, which leads to sustainable energy usage. Energy production profiles, along with users’ energy needs profiles, were analyzed in terms of sustainability, investment payback time, and energy loss in the face of the new Polish Renewable Energy Law. Recent changes in the Renewable Energy Law in Poland, which came into force on the 1 April 2022, have changed the way many investors are thinking about investing in photovoltaic systems. The main difference is how the Energy Distributor is obliged to trade the photovoltaic electrical energy injected into the grid by Prosumers. The so-called “net metering”, which is kind of a barter deal, was changed to “net billing”—selling energy at a wholesale price. Net billing is believed to be less profitable than net metering due to a significant price difference between the bought and sold energy.

Collaborative optimization of thermal and economic performances of a tower solar aided coal-fired power generation system

• New operation strategy of solar aided coal-fired power generation unit is proposed. • The system annual performances in different solar irradiation levels are studied. • Collaborative optimization of the proposed system configurations is carried out. • Multi-time scale thermal performance analyses of the proposed system are conducted. • The sensitivity analyses of the economic parameters of solar field are explored. This paper studies a novel tower solar aided coal-fired power generation (TSACPG) system with thermal energy storage (TES) system to realize the high-grade solar energy cascade utilization and puts forward an improved annual operation strategy of the system. The variations of annual electricity output from solar, annual solar to electricity efficiency and solar field levelized cost of electricity (LCOE) of the proposed TSACPG system under different solar multiples and thermal energy storage hours are explored in different level direct normal irradiation (DNI) sites. Collaborative optimizations of the TSACPG system configurations are performed by the non-dominated sorting genetic algorithm-II. The results demonstrate that the annual electricity output from solar is positively correlated with yearly DNI level and ascends with the increases of both TES hour and solar multiple. The annual solar to electricity efficiency descends with an increasing solar multiple and ascends with an increasing TES hour. The solar field LCOE will initially descend with the increase of solar multiple to the minimum and then ascend, and it will also ascend with an increasing TES hour. The improved operation strategy proposed is superior to the simple operation strategy in terms of both thermodynamic and economic performances. The pareto fronts in different level DNI sites are obtained with the simultaneous optimization of the annual electricity output from solar and the solar field LCOE. The best compromise solutions are obtained. The optimal TES hours and solar multiple values in high, medium and low level DNI sites are 14.14 h/2.64, 14.22 h/2.61 and 12.15 h/2.52, respectively. The multi-time scale analyses of the TSACPG system in different level DNI sites are conducted. The results suggest that the electricity output from solar is relatively high and the solar to electricity efficiency is comparatively low in high level DNI sites. The daily performance result implies that the system has a better performance in high level DNI site, which provides an important reference for the actual design of the system. Economic analysis reveals that the tower solar system investment payback time shows the superiority in high level DNI site and the investment payback time exhibits a trend towards shortening with an increasing coal price. Meanwhile, the sensitivity results of economic performance indexes show that the TSACPG system economic performance is closely related to the price of system components, which exhibits the impact of market changes on economic benefits for decision makers.

Multi-objective optimization of series system for heat recovery: Technical and economic tradeoff

The refrigeration system on fishing vessels consumes a lot of fuel and increases carbon emissions. The absorption system for ice-making driven with the waste heat of the internal combustion engine is a feasible method to achieve "Nearly Zero Energy" freeze preservation. In this paper, firstly, the ammonia absorption cycle driven by the waste heat of the fishing boat was thermodynamically modeled, and it is found that the absorption chiller's performance is affected by the engine power, cooling water temperature. Secondly, by establishing a thermo-economic model, taking the capital, operation cost into consideration, the thermal economy of the system is analyzed; finally, through the multi-objective of the genetic algorithm, Pareto optimal frontiers of the system were presented. Different clusters of the optimal results show that the investment payback time can reach 2.50 years and 2.58 years; with exergy efficiency 37.81% and 37.86%, respectively.

Energy consumption reduction of a center-pivot with the use of a variable-frequency drive

Pressure demand of a center-pivot can be controlled by variable frequency drives during irrigation system operations, leading to a rational use of electrical energy. However, numerous studies encountered problems due to the lack of field data to perform the simulations. The objective of this study was to simulate the reduction of the average value of the active electrical power required to drive the pumping unit of a center-pivot irrigation system by controlling the rotational speed through a frequency inverter. The simulation was conducted considering a complete rotation of the lateral line of a central pivot, installed in an area of 70-ha, in the municipality of Formiga-MG. The simulation demonstrated the possibility of reducing the active electrical power required for the pivot pump by 18%, from an average of 131 to 107 kW. For 1300 pumping hours per year, the investment's payback time would be two and four years for the highest (R$ 0.48 kWh-1) and lowest energy cost (R$ 0.32 kWh-1), respectively. Results suggest that irrigated areas by center-pivot with variations of topographic altitude require technical-economic evaluations for using frequency inverters.

Simultaneous Production of Solar Thermal Heat and Power for Industrial Applications

Currently most of the energy production is supported by fossil fuels, however, renewable sources contribution on worldwide demand of energy has been in constantly growth. One of the main challenges in the use of solar thermal energy in industrial processes is their cost, especially when is compared to energy generation by fossil fuels. This cost delimits the investment payback time for a thermo-solar installation to be feasible. This fact makes crucial the development of methodologies for the integration of solar energy for large-scale industrial applications. This work deals with the thermo-economic evaluation of the heat and power production through a low-temperature flat-plate solar collector system. Also, strategies were developed to increase energy efficiency by evaluating different process integration scenarios. The proposed strategies for energy efficiency combined with renewable energy were applied to an integrated solar thermal energy system into a 1G and 2G (first and second generation) bioethanol process from sugarcane. It was found that to replace the fully process heat and power with low-temperature solar thermal energy, a heat recovery network ? ?? ?????? of 5 °C, a heat duty of 131 kW and a supply temperature of 105 °C are required. All these results lead to a cost of 0.2112 USD/kWh of the integrated system. The power system operates independently by mean an Organic Rankine Cycle and the heating system is supplied by a solar collector network with a cost of 0.0477 USD/kWhele.

LCA evaluation and Energy performance of a housing building in different technological scenarios

Reaching nearly Zero Energy Building (nZEB) standards through retrofit can be achieved by adopting controlled procedures and assessment tools. The main issue of operational energy consumption before and after refurbishment should be calculated with reliable predictive models to support investment payback time evaluations. For that purpose, dynamic simulation can reduce the performance gap between simulated and actual performance, however, multiple issues are involved. In the EU Directives, the nZEB framework addresses the operational consumption, which traditionally was the main portion in the building life cycle. However, where nZEB is concerned, the running energy is strongly reduced and embedded energy and disposal assume a higher contribution to the energy life cycle cost. It is worthy to note that LC-ZEBs (Life Cycle Zero Energy Buildings) have been conceptualized more than 10 years ago and the LCA (Life Cycle Assessment) approach is now integrated into the most advanced CVEs (Calculation Virtual Environments) to enable a broader evaluation of building energy during the lifespan. The paper presents LCA scenarios for a housing case study located in Italy and Norway where energy saving is regulated and suitable solutions are strongly connected to materials and energy supply contexts.

Integration of spent coffee grounds valorization for co-production of biodiesel and activated carbon: An energy and techno-economic case assessment in China

Over 10 million tons of coffee were consumed globally every year, resulting in an enormous amount of spent coffee grounds (SCG) waste to be processed. However, in many parts of the world, the SCG is treated as general waste and usually ends up in landfill or incineration. This practice is a waste of resource and also can cause environmental pollution. SCG has a fine cellulosic fiber structure and contains a considerable amount of lipid. It can be considered as a promising feedstock for bioenergy and biomaterials production. Before building a processing plant, it is essential to evaluate the feedstock characteristics and thermal conversion routes to fully understand the process's technical feasibility and economic viability. This work developed a comprehensive process model for the integrated SCG valorization process to evaluate the energy flow, production efficiencies, and costs for co-production of biodiesel (BD) and activated carbon (AC) in Changsha, China. The results showed that the SCG valorization system can co-produce BD, AC and glycerol with product yields of 13.41%, 14.06% and 2.24% (wet feed basis), respectively. The overall production efficiency was calculated to be 30.5%. The fuel gas produced from the pyrolysis process can meet part of the process heat demand, but additional natural gas is required to provide sufficient heat for the conversion process. Significant energy consumption occurs in hexane recovery, char activation, and SCG carbonization subsystems, accounting for 39.4%, 21.0%, and 18.4% of the total energy consumption, respectively. The minimum selling prices of the BD and AC are calculated to be CNY 1.83/kg and CNY 4.42/kg, respectively, which are well below their current market prices. The base case scenario can make the plant profitable, but the investment return and payback time may not be attractive enough to the investors. Process developers should identify optimum plant locations and endeavor to improve the market values of the products in order to enhance the economic viability.