- freely available
Energies 2019, 12(12), 2307; https://doi.org/10.3390/en12122307
1.1. Shifting to 100% Renewable Energy
- Resources: fuels, electricity (source);
- Conversion/exchange and storage technologies (system);
- Final demand: user behavior end-uses (Service).
- 100% renewable heat and electricity and fossil free transport and industry;
- Sustainable biomass;
- Isolated energy system;
- System balances itself;
- Technically feasible technologies.
1.2. Aim of this Article
- The 100% renewable city energy system configuration and role of the technologies within the national 100% renewable energy system;
- The implications for Sønderborg for bioenergy, wind, and solar resources within the context of the national energy system and key sustainability factors.
- City energy system diagnosis today: Define boundary conditions for the city and gather energy dataset for the city for a recent year;
- National long-term energy study and per capita data: Locate a national study that has both an energy system scenario for a recent year and that looks at 100% renewable energy in the long-term, i.e., 2050. The scenarios should meet specific characteristics, which are described in more detail below;
- Per capita energy data for the city in the future: Quantify per capita energy data for city energy system based on the national long term 100% renewable system (2050);
- Analyze and balance the city energy system: Using the per capita data for the city in 2050 and an energy system analysis tool, assess the city energy system in 2050 with regards to the sustainability factors.
2.1. Step One: City Energy System Diagnosis Today
2.2. Step Two: National Long-Term Energy Study and Per Capita Data
2.3. Step Three: Per Capita Data for the City in the Future
2.4. Step Four: Analyze and Balance the City Energy System
- The local energy system that exists today, e.g., district heating network (Step 1);
- The energy system of the country in 2050 and the technologies that can be used locally (Step 2 and 3);
- The sustainability factors are met, for example all energy sectors are included and energy demands are met, resource consumption is low and energy is efficiently used, i.e., district heat is not being overproduced (Step 4)
2.4.2. Balancing the National Energy System with Power Plants
2.4.3. Using the Simulation Tool
3. Applying the Methodology in Sønderborg
3.1. Step One: City Energy System Diagnosis Today
3.2. Step Two: National Long-Term Energy Study and Per Capita Data
3.2.1. Danish Changes to 2050
- Heat demand in buildings was reduced by 40%, which was based on the cost of renovations against the cost of supplying heat.
- Household electricity savings were reduced by 25%, which was based on three factors:
- The future increase of equipment of 10%;
- Technical savings of 15%;
- Behavioral savings of 20%.
- Industry and service sectors, including agriculture and construction, assumed business as the usual growth of 40%. This energy demand was reduced via savings for fuel and electricity and a coordinated implementation of district heating and cooling, electric heat pumps, and replacement of fossil fuels with electricity, biomass, and upgraded hydrogen (methanated biogas).
3.2.2. Comparing the Per Capita Energy Data of Denmark and Sønderborg
3.3. Step Three: Per Capita Energy Data for the City in the Future
4. Results: Step Four—Analyze and Balance the City Energy System
4.1. Data Type 1—Resource Inputs
4.2. Data Types 2 and 3—Conversion Technologies (Production) and Storages and Exchange
4.2.1. Electricity Production
4.2.2. District Heating and Private Heating
4.3. Data types 4, 5, and 6—Final Energy Demands, End-Use Demands and Total Energy Sector Demands
4.4. Potential Investments Towards 2050
5. Discussion and Conclusions
Conflicts of Interest
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|Smart Energy System Sustainability Factors ||Explanation |
|Includes all energy sectors||Decarbonize all energy sectors. Synergies are maximized and resource consumption is minimized|
|Technically feasible design and analysis||Energy imbalances are minimized and unit capacity factors are sufficient|
|Feasible socio-economic costs||Equal to today, sufficient balance of payments, macro-economic fiscal effects|
|Feasible energy security||Energy demands are supplied throughout the year|
|Better efficiency||Resource consumption is minimized|
|Better resource use||Ecosystem services are maintained|
|Better environment||Reduction in climate change, health improvements, jobs created|
|Resource Inputs (1)||Conversion Technologies, Capacities and Efficiencies (2)||Exchange and Storage, Capacities and Efficiencies (3)||End-User Demands (4)||Final Energy Demands (5)||Total Energy Sector Demands (6)||Temporal Demands and Energy Inputs (7)|
Imported electricity; Renewable energy.
Combined heat and power plant (CHP);
Electricity exchange and distribution (+ losses);
District heating distribution (+ losses).
Light duty vehicles;
Heavy duty vehicles.
|Electrical energy demand;|
Thermal energy demand;
Cooling energy demand;
Transport energy demand.
|Hour by hour|
|Conversion Technologies (2)||Electricity Production (GWh)||Thermal Production (GWh)||Final Energy Demands (5)|
|Wind (onshore)||33 (100%)||-||Electrical & thermal energy|
|Solar PV||16 (100%)||-|
|CHP (decentralized)||5 (37%)||6 (49%)|
|CHP (waste)||28 (13%)||159 (75%)|
|CHP (industry)||16 (38%)||19 (46%)|
|DH boilers||-||271 (~102%)||Thermal energy demand|
|DH boiler (electric)||-||8 (96%)|
|DH solar thermal||-||20 (96%)|
|DH geothermal||-||5 (100%)|
|Industry boilers||-||253 (90%)|
|Private boilers||-||324 (~75%)|
|Solar thermal (private)||-||2 (100%)|
|Heat pumps (private)||-||7 (300%)|
|Electric heating (private)||-||15 (~100%)|
|Private cooling||No data||No data||Cooling energy demand|
|Motors/engines||1.9 (85%)||211 (~25%)||Transport energy demand|
|Resource inputs (1)||Biomass + waste||40||65|
|Solar + geothermal||1||16|
|Conversion technologies (2)||Data available but not presented|
|Storages and exchange (3)||Electricity import||0||0.8|
|Final energy demands (5)||Data available but not presented|
|Total energy sector demand (6) (excluding conversion and distribution losses)||Electricity||31||67|
|Transport (Total energy sector demands excluding conversion and distribution losses were not provided for transport so they were estimated based on efficiencies of vehicles today. Efficiencies were 25% light vehicles, 33% for heavy vehicles, 33% for aviation and shipping, and 85% for electric vehicles.)||16||13|
|Final Energy Demands (5)||Sønderborg 2016 (GWh)||Sønderborg Based on IDA2015 (GWh)||Sønderborg Difference|
|Transport energy||Light vehicles||109||112||−7%|
|Heavy vehicles (including rail)||26||35||−19%|
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