Impacts of demand response from buildings and centralized thermal energy storage on district heating systems

\ua9 2020 The Author(s) Energy use for space heating is a substantial part of total energy end use and heating systems can offer some flexibility in time of use, which should be important in future energy systems to maintain balance between supply and demand. This work applies a techno-economic, integrated, demand-supply optimization model to investigate the combined effect of using demand-side flexibility from buildings, by allowing for indoor temperature deviations (both up- and downward from the set-point), and supply-side flexibility, by applying thermal energy storage (TES), on the operation of district heating (DH) systems. The results indicate that the potential for increased indoor temperature, i.e., demand response (DR), is concentrated to multi-family and non-residential buildings (heavy buildings with high time-constants), while the potential for downregulation of the temperature, i.e., operational energy savings, is utilized to a greater extent by single-family buildings (light buildings). It is also evident that the value of DR diminishes in the presence of a supply-side TES. We show that applying both the demand-side flexibility and a centralized TES is complementary from the heating system perspective in that it results in the lowest total space heating load of the buildings and the lowest running cost for the DH system

Impact of electricity market feedback on investments in solar photovoltaic and battery systems in Swedish single-family dwellings

The profitability of investments in photovoltaics (PVs) and batteries in private households depends on the market price of electricity, which in turn is affected by the investments made in and the usage of PVs and batteries. This creates a feedback mechanism between the centralised electricity generation system, and household investments in PVs and batteries. To investigate this feedback effect, we connect a local optimisation model for household investments with a European power generation dispatch model. The local optimisation is based on the consumption profiles measured for 2104 Swedish households. The modelling compares three different scenarios for the centralised electricity supply system in Year 2032, as well as several sensitivity cases. Our results show total investment levels of 5–20 GWp of PV and 0.01–10 GWh of battery storage capacity in Swedish households in the investigated cases. These levels are up to 33% lower than before market feedback is taken into account. The profitability of PV investments is affected most by the price of electricity and the assumptions made regarding grid tariffs and taxes. The value of investments in batteries depends on both the benefits of increased self-consumption of PV electricity and market arbitrage

Generating low-voltage grid proxies in order to estimate grid capacity for residential end-use technologies: The case of residential solar PV

Due to data restrictions and power system complexity issues, it is difficult to estimate grid capacity for solar PV on regional or national scales. We here present a novel method for estimating low-voltage grid capacity for residential solar PV using publicly available data. High-resolution GIS data on demographics and dwelling dynamics is used to generate theoretical low-voltage grids. Simplified power system calculations are performed on the generated low-voltage grids to estimate residential solar PV capacity with a high temporal resolution. The method utilizes previous developments in reference network modelling and solar PV hosting capacity assessments. The method is demonstrated using datasets from Sweden, UK and Germany. Even though the method is designed to estimate residential solar PV grid capacity, the first block of the method can be utilized to estimate grid capacity or impacts from other residential end-use technologies, such as electric heating or electric vehicle charging. This method presents: • A method for estimating peak demand based on population density and dwelling type. • Generation of low-voltage grids based on peak demand. • Sizing of transformers and cables based on national low-voltage regulations and standards

A Geospatial Comparison of Distributed Solar Heat and Power in Europe and the US

The global trends for the rapid growth of distributed solar heat and power in the last decade will likely continue as the levelized cost of production for these technologies continues to decline. To be able to compare the economic potential of solar technologies one must first quantify the types and amount of solar resource that each technology can utilize; second, estimate the technological performance potential based on that resource; and third, compare the costs of each technology across regions. In this analysis, we have performed the first two steps in this process. We use physical and empirically validated models of a total of 8 representative solar system types: non-tracking photovoltaics, 2d-tracking photovoltaics, high concentration photovoltaics, flat-plate thermal, evacuated tube thermal, concentrating trough thermal, concentrating solar combined heat and power, and hybrid concentrating photovoltaic/thermal. These models are integrated into a simulation that uses typical meteorological year weather data to create a yearly time series of heat and electricity production for each system over 12,846 locations in Europe and 1,020 locations in the United States. Through this simulation, systems composed of various permutations of collector-types and technologies can be compared geospatially and temporally in terms of their typical production in each location. For example, we see that silicon solar cells show a significant advantage in yearly electricity production over thin-film cells in the colder climatic regions, but that advantage is lessened in regions that have high average irradiance. In general, the results lead to the conclusion that comparing solar technologies across technology classes simply on cost per peak watt, as is usually done, misses these often significant regional differences in annual performance. These results have implications for both solar power development and energy systems modeling of future pathways of the electricity system

Estimating national and local low-voltage grid capacity for residential solar photovoltaic in Sweden, UK and Germany

The electric grid\u27s available capacity to accommodate solar photovoltaic on national scales is currently uncertain. This makes decisions about grid capacity expansion, which can be very costly for local grid operators, difficult to make. Yet, knowledge of national solar photovoltaic grid capacity is central in order to formulate realistic solar PV targets and strategies. We present a methodology based on publicly available data to estimate the grid\u27s hosting capacity of residential solar photovoltaic at both the national and local scale. The model is applied to Sweden, Germany and the UK and shows that low-voltage grid capacity for residential solar photovoltaic is very large, 33 (+5/-7) GW (Sweden), 248 (+5/-24) GW (Germany) and 63 (+1/-14) GW UK, and similar to current total generation capacity. Based on our estimations, we find that with the capacity of the present grid Sweden can supply 24%, Germany 60% and UK 21% of their current annual net electricity consumption from residential solar photovoltaic. In addition, we find that the grid-supported individual solar PV system sizes increase as population density decreases. Finally, our work highlights the importance of implementing sizing incentives for customers when installing their solar PV systems

Balancing investments in building energy conservation measures with investments in district heating – A Swedish case study

We investigate the cost-optimal mix of reduction in the space heating (SH) demand in buildings, achieved through investments in energy conservation measures (ECMs), and investments in the local district heating (DH) system. The work includes three modeling scenarios, which differ with respect to SH demand reduction targets (no supply side targets) for buildings: without a target (only fuel price drives demand reduction); with a total demand reduction (for the building stock); and with a specific demand reduction (to reach a specific kWh/(m2∙y) value for individual buildings). Special emphasis is placed on the choice of ECMs in buildings. For the scenario without a target for SH demand reduction, the least-cost option is a combination of investments in ECMs, heat generation and in storage technologies, yielding a SH demand reduction of 24% already by Year 2030, and thereafter a decrease of 28% up to Year 2050. The reductions are achieved mainly through investments in ventilation heat recovery systems and insulation of roofs. The scenarios that include SH demand reduction targets give similar demand reductions of about 60% by 2050, as compared to 2020. However, the investment cost for fulfilling the specific target scenario is higher than that for the total target scenario

Vilka aspekter finns det att beakta kring gödselseparering och dess transporter?

I dagens jordbruk finns det en ojämn fördelning utav näringsämnena från den animaliska gödseln. De flesta djurgårdarna är belägna i skogs och mellanbygd där det oftast inte finns tillräckligt med spridningsareal. Ute på slättmarkerna finns mer areal att tillgå men djurtätheten här blir ofta allt glesare och tillgången på stallgödsel minskar. Idag har oftast rena växtodlingsgårdar en negativ fosforbalans på ca – 4 kg p/ha (Wikström, 2020). Att transportera gödsel kostar pengar och kräver oftast att stora volymer transporteras. Tanken är att med modern teknik kunna öka koncentrationen av växtnäringsämnen i gödseln genom att man separerar ut en flytande och en fast fraktion som erhåller olika halter av näringsämnena. Då skulle det bli mer intressant att transportera den separerade gödseln längre sträckor efter som det skulle krävas färre transporter för att uppnå samma fosforgiva. Arbetet har utvärderat om det är mer lönsamt att flytta den separerade gödseln för fosforns skull i en mer koncentrerad vara för att få upp fosforvärden och mull på gårdar som inte annars har tillgång på separerad gödsel samt även undersökt påverkan som transporterna har för miljön. Sammanställningen av all data har bearbetats i ett Excel dokument. Det fanns en tydligt skillnaden mellan separerad gödsel och flytgödsel, främst för miljön men även för ekonomiska aspekter. Vi har sedan valt att visa resultatet i rapporten med linjediagram för att enkelt följa upp skillnaden när det blir lönsamt med att separera gödseln, där har vi tagit hänsyn till en rad olika faktorer, ex kostnad för separering, transport och spridningskostnad och växtnäringsinnehållet mm. Utifrån arbetet har följande slutsatser dragits: • Den fasta fraktionen från separerad svinflytgödsel är lönsamt att transportera från 18 km och uppåt. Den fasta fraktionen från separerad nötflytgödsel är först lönsamt att transportera när sträckan överstiger 45 km. Detta jämfört med att transportera flytgödsel för båda djurslagen. • På gårdsnivå är skruvpress det vanligaste. Det finns mer avancerade och effektivare tekniker men de blir oftast för dyra och komplexa eftersom de andra teknikerna har ler moment och kräver emellanåt kemikaliska insatser. Ekonomiska fördelar finns för att transportera separerad gödsel istället för flytgödsel. Miljömässiga fördelar finns i större utsträckning än ekonomiska fördelar.In today's agriculture, there is an uneven distribution of nutrients from animal manure. Most animal farms are located in forests and intermediate areas where there is usually not enough spreading area. On the plains there is more area available for spreading, however, the number of animals here is often becoming increasingly low and the availability of manure is diminishing. Today, pure crop production farms usually have a negative phosphorus balance of about - 4 kg P / ha (Wikström, 2020). Transporting manure costs money and usually requires large volumes to be transported. The idea is to use modern technology to increase the concentration of nutrients in the manure by separating a liquid and a fiber fraction which obtain different levels of the nutrients. Then it would be more profitable to transport the fiber fraktion of the manure longer distances as less manure has to be transported to achieve the same phosphorus yield. The work will evaluate whether it is more profitable to move the fiber fraction of the manure. For the sake of phosphorus in a more concentrated product to obtain higher phosphorus values and organic matter content on farmland that do not otherwise have access to manure and will also touch on the impact that the transport has on CO2 emission. There was a clear difference between separated manure and floating manure in terms of. We have then chosen to show the result in the line diagram report to easily follow up the difference when it becomes profitable to separate the manure. The following conclusions have been drawn from the work: • The fiberfraction of separated pig manure is profitable to transport 18 km or longer. The fiberfraktion of separated cattle manure is only profitable to transport when the distance exceeds 45 km. This compared with transporting slurry from both species. • At farm level, screw press is the most common. There are more advanced and more efficient techniques, but they are usually too expensive and complex and often require chemical action. • Economic benefits exist for transporting separated manure instead of floating manure. Environmental benefits were greater than economic benefits as there is a more significant difference, when environmental benefits become direct while the economic ones become more profitable at a longer distance

Self-consumption and self-sufficiency for household solar producers when introducing an electric vehicle

The aim of this study was to analyse how electric vehicles (EVs) affect the levels of electricity self-consumption and self-sufficiency in households that have in-house electricity generation from solar photovoltaics (PV). A model of the household electricity system was developed, in which real-time measurements of household electricity consumption and vehicle driving, together with modelled PV generation were used as inputs. The results show that using an EV for storage of in-house-generated PV electricity has the potential to achieve the same levels of self-consumption and self-sufficiency for households as could be obtained using a stationary battery. As an example, the level of self-sufficiency (21.4%) obtained for the households, with a median installed PV capacity of 8.7 kWp, was the same with an EV as with a stationary battery with a median capacity of 2.9 kWh. However, substantial variations (up to 50% points) were noted between households, primarily reflecting driving profiles

Solar photovoltaic-battery systems in Swedish households - Self-consumption and self-sufficiency

This work investigates the extent to which domestic energy storage, in the form of batteries, can increase the self-consumption of electricity generated by a photovoltaic (PV) installation. The work uses real world household energy consumption data (measurements) as the input to a household energy consumption model. The model maximizes household self-sufficiency, by minimizing the amount of electricity purchased from the grid, and thereby also maximizing the level of self-consumption of PV electricity, i.e., the amount of PV-generated electricity that is consumed in-house. This is done for different combinations of PV installation sizes (measured in array-to-load ratio; ALR: ratio of the PV capacity to the average annual electric load of a household) and battery capacities for different categories of single-family dwellings in Sweden (i.e., northern latitudes). The modeling includes approximately 2000 households (buildings). The results show that the use of batteries with capacities within the investigated range, i.e., 0.15-100 kW h, can increase the level of self-consumption by a practical maximum of 20-50 percentage points (depending on the load profile of the household) compared to not using a battery. As an example, for a household with an annual electricity consumption of 20 MW h and a PV installation of 7 kW,,, this range in increased self-consumption of PV-generated electricity requires battery capacities in the range of 1524 kW h (actual usable capacity), depending on the load profile of the specific household. The practical maximum range is determined by the seasonality of PV generation at Swedish latitudes, i.e., higher levels of increased self-consumption are possible, however, it would require substantially larger batteries than the up to 100 kW h investigated in this work. Thus, any additional marginal increment in battery capacity beyond the range investigated results in a low level of utilization and poor additional value. Furthermore, our results reveal that when a battery is used to store PV-generated electricity in-house, self-sufficiency increases (as compared to not using a battery) by 12.5-30 percentage points for the upper range of the investigated PV capacities (ALR. of 6). (C) 2016 Elsevier Ltd. All rights reserved

Demand response potential of electrical space heating in Swedish single-family dwellings

This paper investigates the potential and economics of electrical space heating in Swedish single-family dwellings (SFDs) to provide Demand Response (DR) for the electricity load in Sweden.A dynamic and detailed building-stock model, is used to calculate the net energy demand by end-use of a set of sample buildings taken as representative of all Swedish SFDs with electrical heating. A new sub-model optimizes the dispatch of heating systems on an hourly basis, for each representative building, minimizing the cost of electricity purchased from the hourly spot market.The analysis of the Swedish SFD buildings indicates a technical DR capacity potential of 7.3 GW, which is considerable and can be used for the management of intermittent electricity generation. This potential could also prove to be valuable in the operating reserve market. However, this requires that the DR, rather than being governed by a single hourly electricity price signal, would instead be subject to a more centralized control. The modeling shows that DR can be expected to result in up to 5.5 GW of decreased load and 4.4 GW of increased load, if applying current Swedish electricity prices. The modeling shows that DR shifts up to 1.46 TWh of electric heating, corresponding to 1% of total Swedish electricity demand. The potential savings from DR for individual SFDs is found to be low, 0.9–330 €/year, given current Swedish electricity prices