The Global Grid
Highlights
► A globally interconnected electricity transmission network as a future alternative. ► Technologically and economically feasible as an option for a 100% renewables future. ► Present new opportunities and discuss possible investment and operation schemes. ► Envision a Global Electricity Market, Global Regulator and Global System Operator. ► Working groups to examine in detail such an option should be formed.
Introduction
Increased environmental awareness has led to concrete actions in the energy sector in recent years. Examples are the European Commission's target of 20% participation of renewable energy sources (RES) in the EU energy mix by 2020 [1] and California's decision to increase renewable energy in the state's electricity mix to 33% of retail sales, again by 2020 [2]. At the same time, several studies have been carried out investigating the possibilities of a higher share of renewables in the energy supply system of the future. For instance, the German Energy Agency (DENA) assumes 39% RES participation by 2020 [3], while a detailed study from the National Renewable Energy Laboratory suggests that meeting the US electricity demand in 2050 with 80% RES supply is a feasible option [4]. In Refs. [5], [6], a 100% renewable energy supply system in Europe with interconnections in North Africa and West Asia is discussed. A similar study on a global scale was carried out by WWF and Ecofys in Ref. [7]. The study concluded that a 100% renewable energy supply by 2050, although an ambitious goal, is both cost-effective and technically feasible. More recently Ref. [8], investigated “the feasibility of providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight”. The authors made a detailed analysis and proposed a plan for implementation. They found that the barriers to the deployment of this plan are not technological or economic, but rather social and political.
All these studies suggest that for an efficient integration of more renewable sources in the current system, a reinforcement of the transmission system is necessary in order to reliably satisfy the energy demand. In Ref. [3], the need for constructing 1700–3600 km additional transmission lines in Germany and the neighboring regions is emphasized, in order to avoid non-transmissible power from a 39% RES penetration in the German electricity system. Towards the same end, the “Tres Amigas” project has been initiated in the US in order to interconnect the three US transmission systems and facilitate increased RES integration (www.tresamigasllc.com). Benefits from interconnection are also pointed out in Ref. [9]. The authors studied the interconnection of 19 dispersed wind generation sites and found that, on average, 33% of the yearly averaged wind power can be used with the same reliability as a conventional power plant.
At the same time, long transmission lines are being considered for harvesting renewable energy from remote locations and delivering it to major load centers. Paris et al. seem to have presented the first feasibility analysis of this kind [10]. Later, a study about the construction of a large hydro power plant at the Congo River (Inga Dam) in Central Africa and the transmission of the produced power to Italy was also reported [11]. The conclusion was that such a solution was both feasible and economically competitive. Similarly, in Ref. [12], the profitability of producing electricity from geothermal and hydro power plants in Iceland in order to transmit it and sell it to the UK was demonstrated. Currently, almost 20 years later, the two governments are discussing ways to realize this project [13]. In Ref. [6], it was also suggested that interconnecting Europe to power plants in regions with higher RES potential such as North Africa, Russia, and West Asia3 could have a cost comparable to the current system. Ref. [14] focused on the Russian RES potential and argued that “an EU–Russian cooperation in the renewable energy field would present a win–win situation”. Russian renewable energy could help to achieve the EU environmental targets, while, at the same time, “Russia could begin to develop a national renewable energy industry without risking potential price increases for domestic consumers”. Significant network reinforcements, in the form of a Russian–EU Supergrid, would be necessary in such a case.
Concrete actions have been taken to exploit the benefits of interconnections. EU guidelines already encourage transmission projects such as the Baltic Ring [14]. Projects such as Desertec (www.desertec.org), Medgrid (www.medgrid-psm.com), and Offshore Grid (www.offshoregrid.eu) have been launched, in order to interconnect Mediterranean states with Europe and transfer renewable energy from the African deserts or North Sea to the major load centers. At the same time, initiatives such as Gobitec (www.gobitec.org) in Asia and Atlantic Wind Connection (www.atlanticwindconnection.com) in the USA aim to interconnect the Asian power grids or transmit off-shore wind energy to the US East Coast.
However, many of these ideas have still remained regional or inter-regional in nature, concentrating in Europe and its neighboring regions, North America, or Asia. Comparing the electricity network with networks of similar magnitude, such as the transportation or the telecommunications network, one realizes that several of them have already managed to span the globe. It seems that the only network of similar size which does not form interconnections over the world is the electric power grid.
This paper suggests the next logical step for the electricity network: the Global Grid. The energy needs of the Earth's population will continue to grow [15]. In the search for green electricity, new sites will be exploited, even further from the load centers and the current power grids. A point will be reached, where a RES power plant will be in equal distance from two power systems on different continents. A wind farm in Greenland, for instance, would be a realistic example of such a situation. Our analysis in Section 2.3 shows that connecting such a wind farm to both Europe and North America is a profitable solution. From there, an interconnected global power grid can start to form.
Searching the literature for similar concepts, in Refs. [16], [17] intercontinental interconnections between Russia and North America or Europe and Africa have been discussed, which would eventually lead to a globally interconnected grid. The authors describe the benefits that would arise from tapping unused renewable potential from remote locations, by supplying the consumers with “cheap” energy, while they briefly mention opportunities stemming from the time zone and seasonal diversity. They further qualitatively investigate the feasibility of such interconnections and the benefits to society due to the reduced carbon footprint. Similarly, the GENESIS project is described in Ref. [18], projecting a world where electricity will be generated from an abundant number of solar photovoltaics, and global interconnections will transmit the power to regions where there is night. Assuming a global electricity grid, the authors in Ref. [19] model the global solar and wind patterns based on realistic data and present simulation results. Their focus is on the optimal generation mix for a 100% sustainable electricity supply. Along with these studies, an initiative launched by the Global Energy Network Institute was developed to support such concepts, demonstrating the benefits of global interconnections and compiling related material (www.geni.org).
This paper introduces the concept from a more technological point of view, focusing on the transmission grid, while it also refers to transmission investments and network operation schemes. After an illustration of the concept as we envision it in Section 2, Section 3 will highlight the emerging opportunities for the Global Grid from a power engineering perspective. Section 4 will discuss transmission investments in a Global Grid environment, while Section 5 speculates about possible operational schemes based on the new market structures. After a brief discussion in Section 6, the paper concludes with Section 7.
Section snippets
The Global Grid: an illustration
Before continuing our analysis, the current section is devoted to a brief description of the Global Grid as we envision it. This will hopefully produce a better understanding of the proposed concept. Towards this end, a realistic example leading to intercontinental interconnections is also included. Fig. 1 illustrates a possible Global Grid. Issues pertaining to the power generation and transmission of the Global Grid are described below.
Opportunities
The main driving force behind the Global Grid will be the harvesting of remote renewable sources. However, going global allows multiple new opportunities to emerge, providing a significant incentive for the successful implementation of this concept. A brief analysis of some of them follows.
Investments
Probably one of the concerns when one envisions a Global Grid is its cost. The necessary infrastructure for the realization of the Global Grid involves investments in the range of billions of dollars for each interconnection. This is, however, comparable to current investments in the energy sector. Projections estimate the creation of a European offshore grid, connecting a large number of wind farms in the North Sea, at about €70–90 billion (€1 billion = 109 €) [36]. The fourth generation
Operation
Besides competition, both within the region and between the lines, interconnectors could facilitate the establishment of market couplings, eventually leading to a common global market environment. For instance, NorNed and BritNed in the European region, along with the existing interconnections, led to the coupling of the Nordic and the UK electricity market to Central Europe, forming and expanding the Central West European electricity market (CWE, see www.casc.eu). The NordBalt interconnection
Discussion
Alternatives of the Global Grid for the global energy supply of the future can also be envisioned.
A reasonable assumption would be to continue with the “business as usual”, where fossil fuels and nuclear energy will account for the majority of the energy supply. Nevertheless, increasing environmental awareness, the approaching decline of world oil production (peak oil), increasing prices, and the concerns for oil and gas security of supply are changing the current paradigm and will probably
Conclusions
The Global Grid advocates the connection of all regional power systems into one electricity transmission system spanning the whole globe. Power systems currently are forming larger and larger interconnections, while ongoing projects plan to supply, e.g., Europe with “green power” from the North Sea or the African desert. Environmental awareness and increased electricity consumption will lead more investments towards renewable energy sources, abundant in remote locations (off-shore or in
Acknowledgments
This paper was not funded by any interest group, company, or government agency. The authors would like to thank Prof. Louis Wehenkel, Dr. Thilo Krause, and the reviewers for their helpful comments.
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