thinking big: towards a global power grid

Center for Electric Power and EnergyDepartment of Electrical Engineering

Thinking Big: Towards a Global Power Grid

Spyros ChatzivasileiadisAssistant ProfessorTechnical University of Denmark (DTU)

Climate Parliament RoundtableNew Delhi – December 5, 2017

DTU Electrical Engineering, Technical University of Denmark

DTU Center of Electric Power and Energy

• Part of the Department of Electrical Engineering

• Among the strongest university centers in Europe with ~100 employees

• Direct support from Siemens, Danfoss, and other big Danish companies

• Denmark has the highest proportion of wind power in the world

• DTU ranks in the top 10 universities in the world in Energy Science and Engineering (2015, 2016)

5 December 20172 Spyros Chatzivasileiadis

Denmark


Towards a 100% Renewable Energy Future

Paris agreement on climate change:

• Targets to reduce emissions by 194 states

• Signed by USA, China, India, and the EU à represent ~60% of global CO2 emissions

Studies for a 100% RES energy production

5 December 20173*RES: Renewable Energy Sources

Spyros Chatzivasileiadis


In power generation we are reacting:• Renewables are already the dominant

investment choice– Decreasing costs– Led first by Europe, now by China,

India, USA

Not a scarcity problem:• RES are abundant; enough to cover

the world’s energy needs

But the path from installed capacity to electricity generation is still long:• Massive amounts of RES are usually

far from largest consumer centers

Strong and flexible transmission is a key enabler:• Interconnections at regional level are

taking place


RES potential in the world

Location of the demand


Interconnections increase reliability and decrease the need for balancing power

• Fully renewable European system

• Interconnector capacities 5.7x larger

• 32 GW less balancing power (~32 nuclear power plants)

5 December 20175

We define the Unconstrained layout as that in which all linkshave capacities equal to the maximum recorded exchange, so thatpower can flow unconstrained along the interconnectors. By con-struction, these give rise to the full benefit of cooperation, as theyallow the interactions between countries to be identical to one inwhich they are all aggregated. The sum of the transmissioncapacities

TC ¼XL

l¼1max

n!!!f"l!!!;!!!fþl

!!!o

(26)

over the larger NTC value of each interconnector in the presentlayout adds up to around 73 GW. With 840 GW the Unconstrained

layout capacities are 11.5 times larger. These unconstrained ca-pacities are determined by single, 1-h events over eight years ofdata. Therefore, we consider the 1% and 99% quantiles of the flowdistributions to define a reduced, directed capacity layout, whichwe call the 99% Quantile layout; see again Fig. 4. This means thatpower will flow unobstructed for 98% of the time. The remaining 2%corresponds to around one week per year. The 99% Quantile layoutcomes with 395 GW in total and is roughly half as large as theUnconstrained layout, but still 5.7 times larger than today’s inter-connector capacities. See Table 3.

3.3. Constrained power flow

To determine what fraction of the benefit of transmission isobtained with a non-ideal, limited transmission capacity, we dealwith constrained power flows as defined in (21). This allows thedetermination of a compromise between the reduction inbalancing energy and the increase in total transmission capacity.

As can be seen in Table 2, the 99% quantile capacities provide,with b ¼ 97.6%, most of the benefit of the Unconstrained layoutwith less than half of the total installed capacity. The layout definedby these 99% quantiles can be seen in Fig. 3(c). It is also noteworthythat today’s capacities already provide 35.5% of the benefit oftransmission, if applied to this scenario. In order to find out how thebenefit scales with increasing transmission capacities, ways ofinterpolating between today’s system and the larger layouts arenow defined.

Interpolation A is an upscaling of present capacities with a linearfactor a. That is, for a directed link l, the limits are defined by

f Al ¼ minnaf todayl ; f 99%Ql

o; (27)

where f todayl represents the NTC of the link as of 2012 and f 99%Qlthose of the 99% Quantile layout.

Interpolation B involves a linear reduction of the 99% quantilecapacities with factor b, that is

f Bl ¼ bf 99%Ql : (28)

Interpolation C defines the capacity layout

f Cl ¼ f cQl ; (29)

which allows unconstrained flow for a percentage c of time, asshown by the different quantiles in Fig. 4. Here, more capacity isallocated to more transited links than to less used ones.

Fig. 3. Transmission network topology and link capacity, with the links as of 2012[24e26]. (a) Present layout capacities. (b) Intermediate layout, with a total capacity 2.3times larger. (c) 99% Quantile layout, with 5.7 times the total capacity of (a). All threelayouts are described in detail in Table 3. Line thickness represents the larger NTC ofthe interconnector.

Fig. 4. Distribution of unconstrained, non-zero power flows between France andSpain, normalized to the mean load in France (see Table 1). Several low- and high-quantiles are marked for illustration. The dashed red lines represent current capac-ities. The solid red lines show capacities as defined by the Intermediate layout. Zero-flow events occur around 46% of the time, and are not shown. (For interpretation ofthe references to colour in this figure legend, the reader is referred to the web versionof this article.)

R.A. Rodríguez et al. / Renewable Energy 63 (2014) 467e476472

Becker et al (2014)


DTU Electrical Engineering, Technical University of Denmark 5 December 20176

European North-Sea Grid

Cheap RES production over long transmission lines and Supergrids

EuroAsiainterconnector

China interconnections

“Energy Island“:

up to 100 GW Wind



The Global Grid

5 December 20177

Spyros Chatzivasileiadis, Damien Ernst, Göran Andersson,The Global Grid, Renewable Energy, vol.57, p. 372-383, 2013



Smoothing out electricity supply and demand

Load

Load

Wind



Benefits of interconnections•Less need to invest in storage

•Lower volatility of electricity prices

•Enhance security of supply, by increasing the diversification of energy sources

•Boost developing economies and reduce their GHG emissions


Our analysis of individual global interconnections has shown a profit increase of up to 42%


Sharing the Vision

• Zhenya Liu, CEO of the State Grid Corporation of China

– covers 88% of the Chinese national territory

• Book on “Global Energy Interconnection”, Elsevier 2015

5 December 201710

• IEEE Spectrum, August 2015– Flagship magazine of the largest

technical professional organization in the world

• “Let’s build a globe-spanning Supergrid”

188 CHAPTER 5 BUILDING GLOBAL ENERGY INTERCONNECTION

realization of grid interconnection and clean energy allocation at the global level to form a globally interconnected robust smart grid system.

1.2 GLOBAL ENERGY INTERCONNECTIONGlobal energy interconnection refers to the development of a globally interconnected, ubiquitous robust smart grid, supported by backbone UHV grids (channels), and dedicated primarily to the transmission of clean energy (Fig. 5.4). Comprising of transnational and transcontinental backbone grids and ubiquitous smart power grids in different countries covering the transmission/distribution of power at different voltage grades, the globally interconnected energy network is connected to large energy bases in the Arctic and equatorial regions, as well as different continents and countries. It can adapt to the need for grid access for distributed power sources with the capability to deliver wind, solar, ocean, and other renewables to different types of end users. Generally speaking, a global energy interconnection is in effect a combination of “UHV grids plus ubiquitous smart grids plus clean en-ergy,” forming a green, low-carbon platform for global allocation of energy with extensive coverage, strong allocation capability, and a high level of security and reliability. It can link up the grids on dif-ferent continents divided by time zones and seasons to remove resource bottlenecks, environmental constraints and spatio-temporal limitations, realizing mutual support and backup between wind and solar generation and across different regions. This will result in greater energy security, improved eco-nomic benefits and reduced environmental losses to effectively resolve issues of energy safety, clean development, efficiency improvement and sustainability. This development will turn the world into a

FIGURE 5.4 Illustration of Global Energy InterconnectionSpyros Chatzivasileiadis


CIGRE C1.35 Working Group: Feasibility Analysis of Global Grid

• Goal: carry out a detailed feasibility analysis based on actual electricity demand and weather data from all over the world for a global electricity network

• Final report: September 2018


• CIGRE: – one of the most respected global organizations among power

system professionals– over 3’500 experts from around the world

• Working Group: – 26 experts from Europe, Asia, Africa, USA, and Australia


Challenges

Political and Regulatory

• Security of supply– Similar problems for gas and oil– But: electricity cannot be stored

• For importing country: no long-term reserves• For exporting country: RES not exported = economic

loss

• Cost of electricity differs due to differing environmental policies

Technical• Power Systems Protection against blackouts (DC grids)

– Some solutions exist, but at an early stage



Recommendations1. Set ambitious targets and a vision

a. e.g. all energy shall be provided by 100% renewables

2. Need for strong political support to carry out detailed analysesa. Study should span several countries à inter-country

coordination of policy makers and technical expertsb. Shall consider the locations with the best potential for

renewables, e.g. off-shore, in deserts, in different countries, etc. --> lowest costs

3. Need for international coordinating body with financial resourcesa. In Europe, if such interconnections have benefits for a whole

region, they become a “Project of Common Interest”b. ”Projects of Common Interest” receive EU fundingc. Example: Interconnection “Greece-Cyprus-Israel”



Conclusions• Long international interconnections and a Global Electricity Grid

are technically feasible and can be economically competitive

• Several opportunities emerge:– Reduction of balancing power to more than 50%– Electricity as a global commodity

• Several challenges still exist

• Alternatives:– Global Power-to-Gas network– Microgrids

• Strong political support necessary to identify and realize projects of common interest



Thank you!

[email protected]

www.chatziva.com

5 December 201715

Spyros Chatzivasileiadis, Damien Ernst, Göran Andersson,The Global Grid, Renewable Energy, vol.57, p. 372-383, 2013

TEDx Talk by Prof. Damien Ernst


thinking big: towards a global power grid

Documents