# Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System

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## Abstract

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## 1. Introduction

## 2. Methods

## 3. Results

#### 3.1. Total System Costs

#### 3.2. Defossilisation of Sectors

#### 3.3. Metrics for VRE Integration

## 4. Limitations of this Study

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## Abbreviations

a | annum (year) |

BEV | Battery Electric Vehicle |

CCS | Carbon Capture and Sequestration |

CHP | Combined Heat and Power plant |

CO${}_{2}$ | Carbon dioxide |

ETS | Emissions Trading System |

EU | European Union |

FOM | Fixed Operation and Maintenance |

GHG | Greenhouse Gas |

H2 | Hydrogen gas |

HP | Heat Pump |

HVDC | High Voltage Direct Current |

INDC | Intended Nationally Determined Contribution for the Paris Agreement [32] |

KKT | Karush-Kuhn-Tucker |

MV | Market Value |

OCGT | Open Cycle Gas Turbine |

PV | Photovoltaic |

PyPSA | Python for Power System Analysis |

PyPSA-Eur-Sec-30 | 30-node sector-coupled PyPSA model for Europe |

VRE | Variable Renewable Energy |

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**Figure 1.**Costs by country with zero CO${}_{2}$ emissions and optimal transmission. The colour assignments follow Figure 3.

**Figure 2.**Energy flow at a single node. In this model, a node represents a whole European country. Within each node, there is a bus (thick horizontal line) for each energy carrier (electric, transport, heat, hydrogen, and methane), to which different loads (triangles), energy sources (circles), storage units (rectangles), and converters (lines connecting buses) are attached. The lines with arrows show the direction of energy transfer (Source: [29]).

**Figure 3.**System costs for electricity, land transport, and space and water heating in Europe with a changing CO${}_{2}$ limit, assuming the 2030 cost projections from Table 1. Left is the case with cost-optimal transmission, right is with no transmission. Estimated costs for today’s system are marked with a red dashed line.

**Figure 4.**CO${}_{2}$ shadow price in the model as CO${}_{2}$ emissions are restricted in the case of cost-optimal cross-border transmission.

**Figure 11.**Zero CO${}_{2}$ scenario: Methane dispatch (positive when synthetic methane is consumed, negative when produced by methanation) versus average electricity prices.

**Table 1.**Technology assumptions projected for 2030 (FOM is Fixed Operation and Maintenance costs, given as a percentage of the overnight cost).

Quantity | Overnight Cost [${\u20ac}_{2010}$] | Unit | FOM [%/a] | Lifetime [a] |
---|---|---|---|---|

Wind onshore | 1182 | kW${}_{\mathrm{el}}$ | 3 | 25 |

Wind offshore | 2506 | kW${}_{\mathrm{el}}$ | 3 | 25 |

Solar PV rooftop | 725 | kW${}_{\mathrm{el}}$ | 3 | 25 |

Solar PV utility | 425 | kW${}_{\mathrm{el}}$ | 3 | 25 |

Battery power | 310 | kW${}_{\mathrm{el}}$ | 3 | 20 |

Battery energy | 144.6 | kWh | 0 | 15 |

H${}_{2}$ electrolysis | 350 | kW${}_{\mathrm{el}}$ | 4 | 18 |

H${}_{2}$ fuel cell | 339 | kW${}_{\mathrm{el}}$ | 3 | 20 |

H${}_{2}$ steel tank storage | 8.4 | kWh${}_{{\mathrm{H}}_{2}}$ | 0 | 20 |

Methanation | 1000 | kW${}_{{\mathrm{H}}_{2}}$ | 2.5 | 25 |

Ground-sourced HP | 1400 | kW${}_{\mathrm{th}}$ | 3.5 | 20 |

Air-sourced HP | 1050 | kW${}_{\mathrm{th}}$ | 3.5 | 20 |

Large CHP | 600 | kW${}_{\mathrm{th}}$ | 3 | 25 |

Large hot water tank | 30 | m${}^{3}$ | 1 | 40 |

Transmission line | 400 | MWkm | 2 | 40 |

HVDC converter pair | 150 | kW | 2 | 40 |

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**MDPI and ACS Style**

Brown, T.; Schäfer, M.; Greiner, M. Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System. *Energies* **2019**, *12*, 1032.
https://doi.org/10.3390/en12061032

**AMA Style**

Brown T, Schäfer M, Greiner M. Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System. *Energies*. 2019; 12(6):1032.
https://doi.org/10.3390/en12061032

**Chicago/Turabian Style**

Brown, Tom, Mirko Schäfer, and Martin Greiner. 2019. "Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System" *Energies* 12, no. 6: 1032.
https://doi.org/10.3390/en12061032