Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Energy flexibility from the consumer: Integrating local electricity and heat supplies in a building
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. Mälardalen University, Västerås, Sweden.
Show others and affiliations
2018 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 223, p. 430-442Article in journal (Refereed) Published
Abstract [en]

The increasing penetration level of renewable energy requires more flexibility measures to be implemented in future energy systems. Integrating an energy consumer's local energy supplies connects multiple energy networks (i.e., the electrical grid, the district heating network, and gas network) in a decentralized way. Such integration enhances the flexibility of energy systems. In this work, a Swedish office building is investigated as a case study. Different components, including heat pump, electrical heater, battery and hot water storage tank are integrated into the electricity and heat supply system of the building. Special focus is placed on the flexibility that the studied building can provide to the electrical grid (i.e., the building modulates the electricity consumption in response to the grid operator's requirements). The flexibility is described by two metrics including the flexibility hours and the flexibility energy. Optimization of the component capacities and the operation profiles is carried out by using Mixed Integer Linear Programming (MILP). The results show that the system fully relies on electricity for the heat demand when not considering the flexibility requirements of the electrical grid. This suggests that district heating is economically unfavorable compared with using electricity for the heat demand in the studied case. However, when flexibility requirements are added, the system turns to the district heating network for part of the heat demand. The system provides great flexibility to the electrical grid through such integration. The flexibility hours can be over 5200 h in a year, and the flexibility energy reaches more than 15.7 MWh (36% of the yearly electricity consumption). The yearly operation cost of the system slightly increases from 62,273 to 65,178 SEK when the flexibility hours increase from 304 to 5209 h. The results revealed that flexibility can be provided from the district heating network to the electrical grid via the building.

Place, publisher, year, edition, pages
Elsevier, 2018. Vol. 223, p. 430-442
Keywords [en]
District heating, Electrical grid, Flexibility, Optimization, Supply integration
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-228712DOI: 10.1016/j.apenergy.2018.04.041ISI: 000433649900030Scopus ID: 2-s2.0-85046664444OAI: oai:DiVA.org:kth-228712DiVA, id: diva2:1211086
Funder
EU, Horizon 2020, 646529 and No. 774309
Note

QC 20180530

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2019-05-04Bibliographically approved
In thesis
1. Integration of Distributed Renewable Energy and Energy Storages in Buildings
Open this publication in new window or tab >>Integration of Distributed Renewable Energy and Energy Storages in Buildings
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Photovoltaic (PV) is a distributed renewable energy technology that is suitable for integration in buildings. PV reduces the electricity demands as well as the greenhouse gas emissions of buildings. However, the surplus electricity from PV is exported to the electricity grid, which not only lowers the economic performance of the PV but also creates operational problems in the grid. Efficient approaches should be identified to improve PV’s economic and environmental performance.

Buildings differ by their connections to energy networks. In buildings that are only connected to the electricity grid, electrical energy storages— including battery and hydrogen storage—can mitigate the mismatch between production and consumption. When a grid-connected PV system follows the conventional operation strategy, its economic performance worsens with storage. Two new operation strategies are developed. With a developed optimization framework, operation strategies and storage capacities are optimized simultaneously. Optimization results indicate that both net present value and self-sufficiency ratio are increased by storages. A comparison between battery storages and hydrogen storages shows that the hydrogen storage can compete with the battery counterpart under an optimistic hydrogen storage cost scenario. In addition, the hydrogen storage can better decrease the exported electricity.

In buildings that are connected to the electricity grid and the district heating network, additional energy conversion and storage equipment— including heat pumps, electrical heaters, and hot water tanks—can be installed to form an integrated energy system (IES). After optimal system sizing, the IES decreases the net present cost by 22%, and the self-consumption ratio increases from 43% to 61%. Moreover, the IES serves as a new flexibility measure, and the provided flexibility energy is over 36% of its electricity consumption. During system planning, the system configuration and operation cost are obtained without considering forecast errors. Through the year-round simulation of system operation that considers forecast errors, a corrected operation cost is obtained. The yearly operation cost difference between system operation and system planning is less than 4% and 6% under the high and low forecast accuracy scenarios.

Abstract [sv]

Solcellen (PV) är en distribuerad förnybar energiteknik som är lämplig att integreras i byggnader. PV minskar elförbrukning och växthusgasutsläpp från byggnader. Överskottet från PV exporteras till elnätet. Detta försämrar inte bara PV:ns ekonomiska prestanda, men skapar också operativa problem i nätet. Effektiva metoder bör därför identifieras för att förbättra PV:ns ekonomiska och miljömässiga prestanda.

Byggnader skiljer sig i hur de är anslutna till energinätet. I byggnader som endast är anslutna till elnätet, kan el-lager, inklusive batteri och vätgaslager, utjämna skillnader mellan produktion och konsumtion. Om det nätanslutna PV-systemet följer den konventionella operationsstrategin, försämras den ekonomiska prestandan med el-lager. I denna avhandling har två nya driftsstrategier utvecklats. Tillsammans med ett utvecklat ramverk för optimering, kan driftsstrategier och lagringskapaciteter optimeras samtidigt. Optimeringsresultaten indikerar att både nuvärdet (NPV) och självförsörjningsgraden (SSR) ökar när el-lager används. Jämförelsen mellan batteri och vätgaslager visar att vätgaslager kan konkurrera med batteri under ett optimistiskt kostnadsscenario för vätgaslagring. Dessutom kan vätgaslagring minska exporterad el-mängd bättre.

I byggnader som är anslutna till elnätet och fjärrvärmenätet kan flera energiomvandlings- och lagringstekniker användas, inklusive värmepumpar, direktverkande el och varmvattentankar. Dessa kan installeras för att bilda ett integrerat energisystem (IES). Genom optimering, kan IES minska kostnaden med 22% och självförbrukningsgraden ökar från 43% till 61%. Dessutom fungerar IES som en ny flexibilitetsåtgärd. Den tillhandahållna flexibilitetsenergin överstiger 36% av elförbrukningen. Under systemplanering erhålls systemkonfiguration och driftskostnad utan övervägande av prognosfel. Genom simulering av systemdrift som inkluderar prognosfel erhålls en korrigerad driftskostnad. Kostnadsskillnaden mellan drift av systemet och systemplanering är mindre än 4% och 6% vid hög och låg prognosprecision.

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH Royal Institute of Technology, 2019. p. 56
Series
TRITA-CBH-FOU ; 27
Keywords
Building, PV, Energy Storage, Operation, Optimization, Flexibility
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-250233 (URN)978-91-7873-193-0 (ISBN)
Public defence
2019-06-04, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 2019-05-08

Available from: 2019-05-08 Created: 2019-05-04 Last updated: 2019-05-08Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Zhang, YangCampana, Pietro EliaYan, Jinyue
By organisation
Energy Processes
In the same journal
Applied Energy
Energy Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 201 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf