publications | nworbmot:tombrown

I was a co-author on the following publications (titles link where possible to pre/post-prints, which are free to download, since otherwise subscriptions may be required).

Selected publications

(A full list of publications follows below)

T. Brown, D. Schlachtberger, A. Kies, S. Schramm, M. Greiner, Synergies of sector coupling and transmission reinforcement in a cost-optimised, highly renewable European energy system, Energy, 2018, postprint arXiv:1801.05290, all input data, code and output data on Zenodo, doi:10.1016/j.energy.2018.06.222

Many energy system models focus on single regions, neglecting interactions over transmission grids, while models that include transmission tend to neglect energy sectors beyond electricity. In this paper we brought these two worlds together in highly-renewable scenarios for the European energy system that include transmission between countries and coupling between electricity, land transport and space and water heating. We showed that flexibility from battery electric vehicles (BEV), power-to-gas units (P2G) and long-term thermal energy storage (LTES) make a significant contribution to the smoothing of variability from wind and solar and to the reduction of total system costs. The cost-minimising integration of BEV pairs well with the daily variations of solar power, while P2G and LTES balance the synoptic and seasonal variations of demand and renewables. In all scenarios, an expansion of cross-border transmission reduces system costs, but the more tightly the energy sectors are coupled, the weaker the benefit of transmission reinforcement becomes.
T. Brown, T. Bischof-Niemz, K. Blok, C. Breyer, H. Lund, B.V. Mathiesen, Response to 'Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems', Renewable and Sustainable Energy Reviews, May 2018, open access, postprint arXiv:1709.05716, doi:10.1016/j.rser.2018.04.113

Several myths surround 100% renewable energy systems purporting that they are not feasible, too complicated or too expensive. In this paper we demonstrated how 100% renewable systems are not just feasible, but economically viable too. We provided a comprehensive review of the wide literature on the topic and addressed each of the points critics have directed at highly-renewable energy modelling, including topics such as demand projections, temporal resolution, extreme events, ancillary services, grid reinforcement, fuel sources and technological readiness.
T. Brown, J. Hörsch, D. Schlachtberger, PyPSA: Python for Power System Analysis, Journal of Open Research Software, 6(1), 2018, open access, postprint arXiv:1707.09913, doi:10.5334/jors.188

Python for Power System Analysis (PyPSA) is a widely-used free software toolbox that we developed to simulate and optimise modern energy systems over multiple periods. PyPSA includes models for conventional generators with unit commitment, variable wind and solar generation, storage units, coupling to other energy sectors, and mixed alternating and direct current networks. It can perform load flow calculations, linear optimal power flow and total energy system least-cost multi-period optimisation of investment and operation. It is designed to be easily extensible and to scale well with large networks and long time series.
J. Hörsch, T. Brown, The role of spatial scale in joint optimisations of generation and transmission for European highly renewable scenarios, 14th International Conference on the European Energy Market - EEM 2017, 2017, preprint arXiv:1705.07617, doi:10.1109/EEM.2017.7982024

Different modellers use different levels of spatial resolution in their models, with some using only one node per country for Europe, while others use the full transmission network with thousands of nodes. This can lead to significantly different results. In this paper the effects of the spatial resolution on the results of the optimisation of transmission and generation capacity in Europe are quantified under a 95% CO2 reduction compared to 1990 levels, interpolating between one-node-per-country solutions and many-nodes-per-country using a variant of k-means clustering. The trade-offs that come with higher spatial detail between better exposure of transmission bottlenecks, exploitation of sites with good renewable resources (particularly wind power) and computational limitations are discussed. It is shown that solutions with no grid expansion beyond today's capacities are only around 20% more expensive than with cost-optimal grid expansion.
D. Schlachtberger, T. Brown, S. Schramm, M. Greiner, The Benefits of Cooperation in a Highly Renewable European Electricity Network, Energy, 134, 469-481, 2017, postprint arXiv:1704.05492, all input data, code and output data on Zenodo, doi:10.1016/j.energy.2017.06.004

In this paper we interpolate between two concepts for balancing the variability of wind and solar resources: balancing at continental scales using the transmission grid and balancing locally with storage. This interpolation is done by systematically restricting transmission capacities from the optimum level to zero. We run techno-economic cost optimizations for the capacity investment and dispatch of wind, solar, hydroelectricity, natural gas power generation and transmission, as well as storage options such as pumped-hydro, battery, and hydrogen storage. The simulations assume a 95% CO2 emission reduction compared to 1990, and are run over a full historical year of weather and electricity demand for 30 European countries. In the cost-optimal system with high levels of transmission expansion, energy generation is dominated by wind (68%) and hydro (15%), with average system costs comparable to today's system. Restricting transmission shifts the balance in favour of solar and storage, driving up costs by a third. As the restriction is relaxed, 85% of the cost benefits of the optimal grid expansion can be captured already with only 40% of the transmission volume.

All publications

M. Victoria, K. Zhu, T. Brown, G.B. Andresen, M. Greiner, Early decarbonisation of the European energy system pays off, preprint arXiv:2004.11009
F. Neumann, T. Brown, Transmission Expansion Planning Using Cycle Flows, preprint arXiv:2004.08702
T. Brown, L. Reichenberg, Decreasing market value of variable renewables is a result of policy, not variability, preprint arXiv:2002.05209
T. Brown, D. Schlachtberger, A. Kies, S. Schramm, M. Greiner, Synergies of sector coupling and transmission reinforcement in a cost-optimised, highly renewable European energy system, Energy, 2018, postprint arXiv:1801.05290, all input data, code and output data on Zenodo, doi:10.1016/j.energy.2018.06.222
T. Brown, T. Bischof-Niemz, K. Blok, C. Breyer, H. Lund, B.V. Mathiesen, Response to 'Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems', Renewable and Sustainable Energy Reviews, May 2018, open access, postprint arXiv:1709.05716, doi:10.1016/j.rser.2018.04.113
A. Orths, C.L. Anderson, T. Brown, J. Mulhern, D. Pudjianto, B. Ernst, M. O'Malley, J. McCalley, G. Strbac, Flexibility From Energy Systems Integration: Supporting Synergies Among Sectors, IEEE Power & Energy Magazine, November 2019, doi:10.1109/MPE.2019.2931054
M. Victoria, K. Zhu, T. Brown, G.B. Andresen, M. Greiner, The role of photovoltaics in a sustainable European energy system under variable CO2 emissions targets, transmission capacities, and costs assumptions, Progress in Photovoltaics, 2019, postprint arXiv:1911.06629, doi:10.1002/pip.3198
F. Neumann, T. Brown The Near-Optimal Feasible Space of a Renewable Power System Model, preprint arXiv:1910.01891
M. Victoria, K. Zhu, T. Brown, G.B. Andresen, M. Greiner, The role of storage technologies throughout the decarbonisation of the sector-coupled European energy system, Energy Conversion and Management, 2019, postprint arXiv:1906.06936 doi:10.1016/j.enconman.2019.111977
T. Brown, M. Schäfer, M. Greiner, Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System, Energies, 2019, doi:10.3390/en12061032
F. Neumann, T. Brown, Heuristics for Transmission Expansion Planning in Low-Carbon Energy System Models, accepted to the 16th International Conference on the European Energy Market, 2019, preprint arXiv:1907.10548, doi:10.1109/EEM.2019.8916411
H. Liu, G.B. Andresen, T. Brown, M. Greiner, A high-resolution hydro power time-series model for energy systems analysis: Validated with Chinese hydro reservoirs, MethodsX, 2019, doi:10.1016/j.mex.2019.05.024
H. Liu, G.B. Andresen, T. Brown, M. Greiner, The role of hydro power, storage and transmission in the decarbonization of the Chinese power system, Applied Energy, 2019, postprint arxiv:1810.10347 doi:10.1016/j.apenergy.2019.02.009
K. Zhu, M. Victoria, T. Brown, G.B. Andresen, M. Greiner, Impact of CO2 prices on the design of a highly decarbonised coupled electricity and heating system in Europe, Applied Energy, 2018, postprint arXiv:1809.10369, doi:10.1016/j.apenergy.2018.12.016
D. Schlachtberger, T. Brown, M. Schäfer, S. Schramm, M. Greiner, Cost optimal scenarios of a future highly renewable European electricity system: Exploring the influence of weather data, cost parameters and policy constraints, Energy, 2018, postprint arXiv:1803.09711, doi:10.1016/j.energy.2018.08.070
J. Hörsch, F. Hofmann, D. Schlachtberger and T. Brown, PyPSA-Eur: An Open Optimisation Model of the European Transmission System, Energy Strategy Reviews, 2018, preprint arXiv:1806.01613, doi:10.1016/j.esr.2018.08.012
M. Schlott, A. Kies, T. Brown, S. Schramm, M. Greiner, The Impact of Climate Change on a Cost-Optimal Highly Renewable European Electricity Network, Applied Energy, 2018, postprint arXiv:1805.11673, doi:10.1016/j.apenergy.2018.09.084
F. Hofmann, M. Schäfer, T. Brown, J. Hörsch, M. Greiner, S. Schramm, Principal flow patterns across renewable electricity networks, Europhysics Letters, 2018, postprint arXiv:1807.07771, doi:10.1209/0295-5075/124/18005
J. Weber, H. Heinrichs, B. Gillessen, T. Brown, J. Hörsch, D. Maybe, D. Witthaut, Counter-intuitive behaviour of energy system models under CO2 caps and prices, Energy, 2018, preprint arxiv:1809.03157, doi:10.1016/j.energy.2018.12.052
B. Tranberg, M. Schäfer, T. Brown, J. Hörsch, M. Greiner, Flow-based analysis of storage usage in a low-carbon European electricity scenario, 15th International Conference on the European Energy Market - EEM 2018, 2018, preprint arXiv:1806.02549
T. Brown, J. Hörsch, D. Schlachtberger, PyPSA: Python for Power System Analysis, Journal of Open Research Software, 6(1), 2018, open access, postprint arXiv:1707.09913, doi:10.5334/jors.188
S. Pfenninger, L. Hirth, I. Schlecht, E. Schmid, F. Wiese, T. Brown, C. Davis, B. Fais, M. Gidden, H.Heinrichs, C. Heuberger, S. Hilpert, U. Krien, C. Matke, A. Nebel, R. Morrison, B. Müller, G. Pleßmann, M. Reeg, J. C. Richstein, A. Shivakumar, I. Staffell, T. Tröndle, C. Wingenbach, Opening the black box of energy modelling: strategies and lessons learned, Energy Strategy Reviews, 2017, open access, postprint arXiv:1707.08164, doi:10.1016/j.esr.2017.12.002
J. Hörsch, T. Brown, The role of spatial scale in joint optimisations of generation and transmission for European highly renewable scenarios, 14th International Conference on the European Energy Market - EEM 2017, 2017, preprint arXiv:1705.07617, doi:10.1109/EEM.2017.7982024
D. Schlachtberger, T. Brown, S. Schramm, M. Greiner, The Benefits of Cooperation in a Highly Renewable European Electricity Network, Energy, 134, 469-481, 2017, postprint arXiv:1704.05492, all input data, code and output data on Zenodo, doi:10.1016/j.energy.2017.06.004
J. Hörsch, H. Ronellenfitsch, D. Witthaut, T. Brown, Linear Optimal Power Flow Using Cycle Flows, Electric Power Systems Research, volume 158, pages 126-135, 2017, preprint arXiv:1704.01881, doi:10.1016/j.epsr.2017.12.034
E.H. Eriksen, L.J. Schwenk-Nebbe, B. Tranberg, T. Brown, M. Greiner, Optimal heterogeneity in a simplified highly renewable European electricity system, Energy, 133, 913-928, 2017, postprint arXiv:1706.00463, doi:10.1016/j.energy.2017.05.170
J. Bertsch, T. Brown, S. Hagspiel, L. Just, The relevance of grid expansion under zonal markets, The Energy Journal, Volume 38, Number 5, 2017, EWI Working Paper 15/07, doi:10.5547/01956574.38.5.jber
H. Ronellenfitsch, D. Manik, J. Hörsch, T. Brown, D. Witthaut, Dual theory of transmission line outages, IEEE Transactions on Power Systems, 2017, postprint arXiv:1606.07276, doi:10.1109/TPWRS.2017.2658022
Scaling Up Variable Renewable Power: The Role of Grid Codes, 2016, International Renewable Energy Agency
T. Brown, P. Schierhorn, E. Tröster, T. Ackermann, Optimising the European transmission system for 77% renewable electricity by 2030, IET Renewable Power Generation, Volume 10, Issue 1, 2015, postprint version, doi:10.1049/iet-rpg.2015.0135
T. Brown, T. Ackermann, N. Martensen, Solar Power Integration on the Seychelles Islands, Field Actions Science Reports Special Issue 15: Decentralized Electrification and Development, 2016
L. Jiang, C. Wang, Y. Huang, Z. Pei, S. Xin, W. Wang, S. Ma, T. Brown, Growth in Wind and Sun: Integrating Variable Generation in China, IEEE Power and Energy Magazine, Volume 13, Issue 6, 2015, doi:10.1109/MPE.2015.2458754
Integrating Renewables in Jiangsu Province, China (PDF, 1.2 MB) presented at the 14th International Workshop on Integration of Wind Power into Power Systems in Brussels, 2015
Greenpeace powE[R] 2020 Integration of Renewables in Jiangsu, China (in Chinese), published July 2015, Beijing, English press release
T. Brown, Transmission Network Loading in Europe with High Shares of Renewables, IET Renewable Power Generation, Volume 9, Issue 1, 2015, postprint version, https://doi.org/10.1049/iet-rpg.2014.0114
S. Hagspiel, C. Jägemann, D. Lindenberger, T. Brown, S. Cherevatskiy, E. Tröster, Cost-Optimal Power System Extension under Flow-Based Market Coupling (subscription required, part of the Smooth PV project) in Energy, 66, pp. 654-666, 2014, free to download: EWI Working Paper 13/09, preprint version, doi:10.1016/j.energy.2014.01.025
Optimising the European Transmission System for 77% Renewables by 2030 (PDF, 1.8 MB) presented at the 13th International Workshop on Integration of Wind Power into Power Systems in Berlin, 2014
Cycling Requirements for Conventional Power Plants at High Shares of Renewable Energy (PDF, 0.6 MB) presented at the 13th International Workshop on Integration of Wind Power into Power Systems in Berlin, 2014
The Solar Power Absorption Capacity of the Seychelles Island Systems (PDF, 0.9 MB) presented at the 4th International Workshop on Integration of Solar Power into Power Systems in Berlin, 2014
Wind Power in a 100% Renewables Scenario for Rhineland-Palatinate (PDF, 1.5 MB) presented at the 13th International Workshop on Integration of Wind Power into Power Systems in Berlin, 2014
Solar Power in a 100% Renewables Scenario for Rhineland-Palatinate (PDF, 0.6 MB) presented at the 4th International Workshop on Integration of Solar Power into Power Systems, Berlin, 2014
A Multi-Objective Control Strategy for Distribution Networks with Renewables (PDF, 0.8 MB) presented at the 4th International Workshop on Integration of Solar Power into Power Systems, Berlin, 2014
Greenpeace powE[R] 2030 European report (PDF, 13 MB) for the grid extensions necessary to accommodate 77% renewable electricity in Europe by 2030, 2014
Entwicklung und Durchführung einer Impactanalyse für den Klimaschutzplan Nordrhein-Westfalen (PDF, 2.5 MB), Düsseldorf, 2014
Kurzgutachten zur Eigenstromerzeugung in Rheinland-Pfalz, Darmstadt, March 2014
Distribution network study for Rhineland-Palatinate (PDF, 13 MB, in German) to reach 100% renewable electricity in the German federal state of Rhineland-Palatinate by 2030, summary in English, 2014
UMEME 24/7: Analysis of the Stability of the Kenyan Power System (PDF, 5.5 MB), Darmstadt, 2014
Transmission Network Loading in Europe with High Shares of Renewables (PDF, 1.2 MB), presented at the 3rd International Workshop on Integration of Solar Power into Power Systems in London, 2013
Smooth PV - Smart Modelling of Optimal Integration of High Penetration of Photovoltaics Final Report, 2013
Transporting Renewables: Systematic Planning for Long-Distance HVDC Lines (PDF, 4 MB, part of the Smooth PV project) presented at EWEA 2013 in Vienna
Cost-optimal Power System Extension Under Flow-based Market Coupling and High Shares of Photovoltaics (PDF, 0.3 MB), part of the Smooth PV project) presented at the 2nd International Workshop on Integration of Solar Power into Power Systems in Lisbon, 2012
T. Brown, Complex matrix model duality in Phys. Rev. D 83 085002 (2011) (1009.0674 [hep-th])
T. Brown, Cut-and-join operators and N=4 super Yang-Mills in JHEP 1005 058 (1002.2099 [hep-th]; code and examples of U(N) to S_N reduction)
PhD thesis Gauge/Gravity Duality Beyond the Planar Limit, August 2009
T. Brown, P.J. Heslop and S. Ramgoolam, Diagonal free field matrix correlators, global symmetries and giant gravitons with Paul Heslop and Sanjaye Ramgoolam in JHEP 0904 089 (0806.1911 [hep-th])
T. Brown, Permutations and the Loop in JHEP 0806 (2008) 008 (0801.2094 [hep-th])
T. Brown, P.J. Heslop and S. Ramgoolam, Diagonal multi-matrix correlators and BPS operators in N=4 SYM with Paul Heslop and Sanjaye Ramgoolam in JHEP 0802 (2008) 030 (0711.0176 [hep-th])
T. Brown, Half-BPS SU(N) Correlators in N=4 SYM in JHEP 0807 (2008) 044 (hep-th/0703202)
T. Brown, R. de Mello Koch, S. Ramgoolam and N. Toumbas, Correlators, probabilities and topologies in N=4 SYM with Robert de Mello Koch, Sanjaye Ramgoolam and Nick Toumbas in JHEP 0703 (2007) 072 (hep-th/0611290)
T. Brown, R.F. Griffin, Spectroscopic binary orbits from photoelectric radial velocities, Paper 156: HD 187003 with Roger Griffin in The Observatory, Vol. 121, p. 55-60 (2001)