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One main obstacle to the implementation of low-temperature district heating is the existing infrastructure along with consumer heating devices that were usually designed for higher operating temperatures. If a DHN is installed for a new urban area, these obstacles can be avoided. This study presents an analysis of alternative heat supply scenarios for the newly developing city subdistrict of Kopli (Tallinn, Estonia). The following scenarios were analysed from economic and environmental aspects: scenario A-connection to the existing DHN (supply/return temperatures 95 °C/55 °C, gas-fired boiler house); scenario B-small local DHN (80 °C/40 °C, small gas-fired boiler house); scenario C-small local LTDHN (60 °C/35 °C, small gas-fired boiler house, integrated large-scale heat pump using seawater as heat source). The results of the study have shown that the primary energy consumption per 1 MWh of heat consumed is 1.33 MWh for scenario A, 1.15 MWh for scenario B, and 0.71 MWh for scenario C. To achieve IRR = 7%, a 4 year discounted payback period was calculated for scenario B, with the NPV of 1.000.000 EUR after the period of 10 years. For scenario C, the payback period is more than 5 years, and the NPV is 2.600.000 EUR after 10 years.

Ground source heat pump (GSHP) system is an efficient solution to mitigate energy consumption and environmental emissions in the building sector. Although the GSHP system is categorized among renewable energy technologies, considering the fact that the system's power demand is usually provided by fossil fuel resources, it may not fully meet this classification. One way to offset the GSHP's electricity consumption in a renewable approach is the use of photovoltaic (PV) panels. This paper aims to study the feasibility of a hybrid PV-GSHP system for a residential building in Tehran, Iran. To that end, a numerical model is developed to explore the GSHP system's performance over a 20-year design life, taking several borehole lengths into account. Moreover, the PV modules are simulated by EnergyPlus software. A life cycle cost analysis is also performed to assess the economic viability and optimal design of the PV-GSHP system. The results illustrate that using four PV modules can best cover the system's electricity consumption and the discounted payback period is less than four years. Furthermore, an environmental evaluation reveals that the PV-GSHP system can save 29.2 t of carbon dioxide emissions over the 20-year period compared to the GSHP system.

This paper aims to evaluate the energy-saving potential, affordability and thermal comfort performance of various passive building retrofit measures for a historical building (late nineteenth-century Victorian house) renovation. Three types of interior passive retrofit measures (i.e. internal wall insulation, glazing upgrade and airtightness improvement), classified as traditional and advanced measures, are further grouped into 63 retrofit combinations. In order to evaluate the performance of these defined retrofit combinations, five assessment indicators are proposed, including energy reduction rate, specific initial cost, discounted payback period, space volume reduction rate, and indoor thermal comfort. Under three internal space reduction scenarios with a space reduction rate of 5.2%, 2.6% and 1.3%, these combinations are evaluated and compared, and the most favourable combinations are determined to achieve multiple objectives (maximum energy saving, most cost-effective and most energy-efficient). The influence of the most favourable retrofit combinations on the internal thermal comfort level improvement is also dynamically evaluated using the EnergyPlus simulation tool. The final recommended passive retrofit combination consists of vacuum insulation windows, gypsum air infiltration reduction, and 2 cm thickness of Polyisocyanurate (PIR) panels, with 51.8% of primary energy reduction, a specific initial investment of £144.71/m2 and a discounted payback period of 18 years.

City gate stations receive high pressure natural gas and decrease the pressure by throttle valves. Concurrent with the natural gas pressure reduction, the temperature also drops. Thus, to prevent blocking of the downstream pipeline by the liquid and solid particles, natural gas must be preheated before pressure reduction. Heaters utilized for preheating task, have a low thermal efficiency and consume a large amount of fuel. In addition to the high fuel consumption, they release a huge amount of CO2 into the atmosphere. Therefore, the present study proposes a new system for in-situ fuel consumption elimination at these stations. It utilizes vertical ground-coupled heat pump system as a renewable source of energy to preheat natural gas stream. The system performance was studied at two different climatic conditions of Iran which have also two different natural gas compositions. Results show that the system is completely capable to eliminate in-situ fuel consumption of city gate stations; however, by considering indirect fuel consumption of electrical heat pumps, the system fuel consumption reduction potential was calculated over 65%. It is also able to reduce CO2 emission up to 79%. The discounted payback period is computed around two years, which proves the suitability of offered system.

Nowadays, the production of craft beer in microbreweries has become very popular all over the world. However, recent studies have demonstrated that the craft beer production process in microbreweries can be considered as energy intensive due to the fact that more to 8% of the production cost is allocated to thermal processes such as heating and cooling. Therefore, most microbreweries have been applying some Energy Efficiency actions to their production processes to decrease the amount of energy consumed and maximize the profits. In cases where the amount of energy consumed cannot be reduced using Energy Efficiency actions, Demand Response measures are implemented to reduce the cost of energy needed to supply the different processes involved. From the available literature, most of the studies based on Demand Response in the microbrewery sector have focused on the use of heating resources for the onsite energy generation to directly support the thermal processes. Very few published studies looked at the onsite “electricity” generation with small scale renewable energy sources and onsite energy storage to assist with energy cost reduction strategies. Therefore, this paper develops an optimal energy management model to minimize the energy cost of a microbrewery, under demand response, supplied with a grid-connected photovoltaic system with battery storage system. As a case study, a microbrewery in South Africa has been selected for simulation purposes. The detailed brewing process’s load profile, the solar resource, the system components’ specifications as well as the Time of Use energy cost structure has been used as input to the developed model with the aim of assessing and analyzing the technical and economic performance of the proposed system under the given operation conditions and constraints. The simulation results have shown that, as compared to supplying the microbrewery exclusively by the grid, the break-even point of the proposed supply option happens after 9.5 years of operation, corresponding to ZAR 398583.18 (USD 22592,09) cumulatively spent. For the considered 20 years’ operation lifetime, the projected savings on the lifecycle cost is ZAR 603490.49 (USD 34206,44) or 40.8%. The result of the discounted payback period analysis indicated that the total investment cost may be recovered in 13.8 years. The microbrewery is selected as a case study just to highlight the fact that some processes are critical and cannot be shifted without compromising the quality of the final product. Therefore, the proposed hybrid system, the developed model and the optimization methodology can be applied to any load in different demand sectors (residential, commercial and industrial) implementing demand response measures in order to reduce their operation energy costs.

The main purpose of this study is to evaluate the economic feasibility of the BIPV system as a building envelope material for the whole building skins. The paper is dealing with the lifecycle cost analysis (LCCA) of BIPV system in the capitals of all the European Union member states (EU) as well as the capitals of Norway and Switzerland. The results revealed that by a discount rate of zero, BIPV system could refund all the investment even on the north facades while in terms of traditional building envelope materials as an alternative option for building skins, there would be rarely added benefits after investment. Furthermore, the societal and environmental benefits of a BIPV system in Europe have its greatest impact on the south facade. Moreover, for all the studied directions of building skins with a discount rate of five present in Europe except the north facade, just the quantified amount of societal and environmental advantages of BIPV systems could almost reimburse all the invested money. The results illustrated that the BIPV system as a building envelope material for the whole building skins could reimburse not only all the investment costs but also become a source of income for the building.

The present paper describes the integration of oxygen membranes in cement plants both from an energy, exergy and economic point of view. Different configurations for oxygen enrichment of the tertiary air for combustion in the pre-calciner and full oxy-fuel combustion in both pre-calciner and kiln are examined. The economic figures of merit are compared with those from a standard cryogenic plant. Both oxygen enriched air and full oxy-fuel cases allow for an increase in clinker production, use of alternative fuels as well as on-site electricity production. In addition, the full oxy-fuel cases generate a concentrated CO2 source that can be used for enhanced oil recovery, in combination with biomass gasification and electrolysis for synthesis gas production, or possibly sequestered. The cases with oxygen enriched air provide very promising economic figures of merit with discounted payback periods slightly higher than one year. The full oxy-fuel cases have a discounted payback period of approximately 2.3 years assuming a CO2 selling price of 35 US$/ton. The sensitivity analysis of full oxy-fuel cases clearly shows that for the discounted payback period, the most sensitive parameters are the CO2 price and the clinker selling price.

This paper compares the thermal performance characteristics of LFL and SFL (linear and spot Fresnel lens, respectively) solar collectors for heating identical greenhouses in Chuncheon, South Korea. LFL and SFL collectors with similar storage capacities and Fresnel lens surface areas were tested under the same weather and operating conditions. Both systems were equipped with a dual-axis solar tracker for tracking the sun position and a circulating pump for forced convective heat transfer. Economic analyses of the solar collectors were performed by considering the current interest rate, inflation rate, and electricity prices in South Korea. The available energy per unit area and thermal efficiency were higher for the SFL than for the LFL collector. The discounted payback period decreased and electricity savings increased when the storage capacity was increased with either collector. All results indicate that SFL collector performance was about 7–12% higher than that of LFL collector. It is also noticed that changing the inlet flow rate of the greenhouse heat exchanger may be a good solution for obtaining the seed germination temperatures needed for different crops.

This paper presents the results of a study that estimated the DSM energy saving and load management potential in commercial and government/institutional sectors in Oman (central grid area) and evaluated its impact on generation capacity and energy savings. The end-use (lighting and air-conditioning) energy consumption data have been collected in two major segments of the commercial sector for simplicity and to save time and money. Another unique aspect of the study is the inclusion of the energy savings, in transmission and distribution (T&D) losses that are estimated by using generation expansion planning approach. The study has found that DSM is financially beneficial from customers’ point of view as the discounted payback period of investment in efficient lighting and air-conditioning is between 4 and 12 years of the surveyed sample. From the utility point of view the capacity saving at the horizon year is between 372 and 596 MW and the overall energy saving for the whole planning horizon is about 29–44 TWh. The total avoided cost in generation and capacity saving is somewhere between 416 and 597 million dollars.