Global Renewable Energy Grid Project: Integrating Renewables via HVDC and Centralized Storage Dr. Mohammed Safiuddin, Research Professor Emeritus, [email protected]
President, STS International, [email protected]
Robert Finton, Ph.D. candidate, [email protected]
State University of New York at Buffalo
Abstract Scientific consensus confirms the feasibility of a world powered by wind, water and solar energies. But in a non-fossil energy infrastructure, there exists a pressing need to share renewable resources across international borders. Regional electric grids must be combined into a vast global network. Ultimately we must create a worldwide system that applies careful monitoring of supply and demand through Smart Grid for dispatch of electrical power over a Global Renewable Energy Grid [GREG]. A high voltage direct current (HVDC) transmission system needs to be built to serve as the principal electrical power transport medium. Centralized “send and receive” storage facilities employing pumped hydro, bidirectional fuel cell and battery technologies, can be strategically placed within GREG as needed.
And perhaps most importantly, the set of socio-political overseeing
institutions from each of the nations will be networked together as a whole – to build and operate just as seamlessly as the physical grid.
Introduction The transition to a worldwide wind, water and solar energy infrastructure is necessary for human safety and health. The obstacles to such a major global shift can be categorized as technical, economic and socio-political, with the socio-political challenges being the largest. Researchers have shown that adequate renewable energy resources exist to power the planet, but a detailed and comprehensive proposal for a global energy network has yet to take shape: regional planners need to combine their efforts before this can be achieved. Likewise, complete and clear rules on how to pay for a global energy grid must be established. And top energy administrators in each participant nation have to come together under an umbrella organization, such as at the United Nations. After considering energy economics along with socio-political obstacles and hierarchies, we offer technological suggestions as to how a global grid might be implemented. High voltage direct current (HVDC) transmission is recommended as the clear choice for most efficient and reliable longdistance delivery of electrical power 24/7/52. And, centralized storage mega-plants are proposed for balancing supply and demand across a network of mostly intermittent sources.
Economics If we are to address the rapidly deteriorating climate due to our electrical power plants, then creation of a Global Renewable Energy Grid [GREG] is critical enough to warrant our highest priority. The United States, for example, invested judiciously in its “Interstate Highway” system starting in the 1950s. The interstate system now comprises 46,876 miles. The completion of the system, at a cost of $129 billion, was a cooperative federal-state undertaking. Each state transportation department managed its own program for location, design, right-of-way acquisition, and construction. The states also were responsible for the ownership and maintenance of the system, and in 1981, they began receiving federal funds for maintenance. While riding in the motorcade on one of these highways with late President John F. Kennedy, late Prime Minister Pandit Nehru of India commented “Mr. President you have a strong economy so you can afford such nice highways”. To this, the late President JFK responded; “No, Mr. Prime Minister, we have a strong economy because we have such nice highways”. Similarly, we need not wonder whether our economies can afford the GREG, we must recognize that the global economies will actually get stronger because of it. However, today’s sluggish world economy and massive public debts make it questionable for all nations to commit to GREG with urgency. It is then assumed that both public and private investment would be necessary to make the project realizable. All nations will have to share the responsibility for creating an environment in which renewable generation flourishes, and for building their part of the transmission network. Just as highway networks for transportation of people and products are at the foundation of national and global economies, and are in the public domain, so are the power grid networks for transmission of electrical energy and, therefore, should be in the public domain. The construction of GREG would require a small fraction of global budgets for sophisticated and expensive weapon systems. “TO ACCOMPLISH GREAT THINGS, WE MUST NOT ONLY ACT, BUT ALSO DREAM, NOT ONLY PLAN, BUT ALSO BELIEVE”
2.1 Economic Challenges 2.1.1 Cost-Benefit Determination .Construction of any national high-voltage, high-power grid [GREG] can only be justified by comprehensive analysis of its socio-economic benefits. Increased electrical reliability and efficiency should be included as quantifiable advantages . Results of detailed studies can be published in concise summaries to help gain public consensus in favor of GREG. If we are to address the challenge of global warming and CO2 emissions, then the design alternatives should be evaluated in thermal and emission units and not in monetary units, manipulated by a handful of bankers in their star studded boardrooms.
2.1.2 Cost Allocation Until now, proposed cost allocation schemes have been met with conflict between developed and developing nations. But methods must be devised to spread the cost of new transmission among consumers. A direct tax for end-use could be imposed (e.g. One U.S. cent per kilowatt hour). Or utilities could be made responsible for renting the line, and determine the amount that is passed on to consumers. In nations where the GREG would be a public asset (i.e. already paid for through taxes), no surcharge should be expected for its use. Since GREG would eventually lower the energy costs for all nations, the next cost of electricity to all consumers would substantially decline over the longterm.
2.1.3 Price Control It is possible that nations exporting energy on GREG may see a rise in domestic electricity rates. So, it might be necessary to place caps on the annual percentage rise for consumers in electricity-rich countries, lest public support evaporate.
2.2 Funding a Global Renewable Energy Grid The amount of public funds committed for GREG will have to be hashed out in the halls of national governments and in the Board Rooms of world’s development banks. To provide the balance of what is needed, there are several known mechanisms by which to spur private investment: • Tax Incentives: Investment in beneficial development is rewarded with a reduction in taxes paid on earnings. • Subsidies: Some percentage of an initial capital outlay is drawn from public coffers. • Feed-in Tariffs: Renewable energy providers are guaranteed appropriate compensation should the cost of production exceed wholesale electricity prices. • Bonds: Investors can purchase a stake in renewable development via a government bond with rates of return comparable to existing instruments such as U.S. Treasury Bonds. • Renewable Portfolio Standards: A legal requirement for the ratio of renewable capacity to overall capacity, forcing the hand of energy companies to provide more renewables. • Output Subsidies: Elimination of subsidies and enforcement of a carbon tax for fossil fuel energy production .
2.3 Implementation: Bond Program with Carbon Tax One possible financing strategy would be to rely upon bond issuance along with a carbon tax. Investors purchase renewable energy bonds with fixed rates of return. The bond price would fluctuate inversely with the day-to-day rate of return as common in bond markets. By issuing bonds, national governments can retain centralized decision-making power without adding to short-term expenditures. Such a program has already been introduced to the U.S. Congress . In conjunction
with bond issuance, a carbon tax would be applied to all fossil fuel producers, with cost per ton of carbon content set by the international agency responsible for GREG. Countries would be required to place carbon tax revenues directly into a renewable energy trust fund, much like a highway trust fund derived from gasoline taxes. Europe leads the way globally in levying of carbon taxes. In recent years, though, the cost of polluting has decreased due largely to global recession. To remedy this problem, each GREG participant nation will be required to levy a carbon tax on coal, gas, and oil, while also joining the United Nations’ Clean Development Mechanism (CDM) program. Ideally, renewable energy bond purchasers would receive a CDM credit for emissions reductions in proportion to the amount invested. Given a guaranteed rate of return plus tradable certificates for emissions reduction, a flood of renewable energy investment will follow.
Figure 1: GREG Monetary Flow
Administration and Regulation By far the most formidable obstacles to creating GREG lie in the socio-political realm. Multinational corporations, deeply invested in a fossil fuel energy infrastructure (e.g. in Russia and The U.S.), will pose strong opposition to the change. Top energy administrators will have to consider all stakeholders when planning the transition to wind, water and solar. They will also need to seek wide public support.
3.1 Administrative and Regulatory Challenges 3.1.1 Domestic Challenges Policy makers must regulate for long-term objectives while acknowledging possible conflicts among regional operators, and between producers and consumers. Administrators must oversee transmission right-of-ways, electricity markets and pricing, while considering the varied interests of
producers, utilities, system operators and prosumers [customers with their own wind and solar generators].
3.1.2 International Challenges After committing to a domestic RE-grid, a country will need to seek a balance between national interest and the interests of the planet at-large. International electricity sharing arrangements, placement of transmission interconnects; security concerns, and reliability issues must be addressed. The extent to which wealthy countries will assist developing countries must also be established. Here emerges a requirement for oversight and dispute resolution from an international body not partisan to any particular nation.
3.2 National Administrative Bodies An ideal organizational structure to administer the GREG will involve administrative and regulatory bodies from each of the participant nations. Top level regulators of electrical energy for the world’s three largest consumer regions are identified as examples:
3.2.1 China •
National Energy Administration (NEA): The key functions of the NEA are to implement energy development plans and policies, conduct energy forecasting, approve projects and formulate environmental policy. State Electricity Regulatory Commission (SERC): SERC is responsible to propose laws, set-up pricing and tariff schemes, and enforce technical standards. China Electricity Council (CEC): Under SERC, the CEC conducts safety investigations and regulatory studies. The Council also carries out international exchange.
3.2.2 United States • • •
Department of Energy (DOE): The DOE ensures energy security, promotes innovation, and encourages conservation, establishing a framework for US national energy policy . Federal Energy Regulatory Commission (FERC): Under the DOE, the FERC regulates power generation, utilities, interstate transmission and the sale of electric power. North American Electric Reliability Council (NERC): NERC is a voluntary organization comprised of power producers, utilities, municipalities and electrical cooperatives. Its mission is to ensure that U.S. power supplies are adequate, reliable and secure.
3.2.3 European Union •
Agency for the Coordination of Energy Regulators (ACER): ACER was founded in 2011 with a mission to foster cooperation among regulators of European member states. It is charged to ensure market integration in accord with EU energy policy objectives. European Network of Transmission System Operators (ENTSO): ENTSO is responsible for reliability, optimal management and technical development of the transmission system across the EU. European Grouping of the Electrical Supply Industry (EURELECTRIC): EURELECTRIC serves as the interface between power providers and policy-making institutions. Its objectives include integration of the continental electricity industry and development of sustainable energy.
3.3 Implementation: Increased Authority at IRENA At present, there are three separate United Nations organizations, which support sustainable energy initiatives: the United Nations Educational, Scientific and Cultural Organization (UNESCO), the United Nations Development Program (UNDP) and the United Nations Economic and Social Council (ECOSOC). In addition, the International Renewable Energy Agency (IRENA) acts under UN guidance to “promote the urgent transition” to renewables . In order to augment and centralize authority, the efforts of these organizations can be combined under the guidance of IRENA’s assembly, council and secretariat. Efficient international regulatory coordination and dispute resolution functions would be made possible by a streamlined IRENA.
Figure 1: Administrative Map: China, US, EU under IRENA oversight
Technology 4.1 Technical Challenges Instant delivery of electrical power from multitudes of inter-connected power plants of all sizes and shapes to a multitude of grid connected loads at the flip of a switch is figuratively and literally a "high wire balancing act". When a light switch is turned ON, the set of electrons required to flow through the filament of the bulb must be instantaneously balanced by an equal set of electrons produced at one of the generators somewhere within the grid system. Similarly, when a set of electrons are produced by a generator anywhere on the grid system, they must either flow into a load circuit or into a storage system connected somewhere to that grid. With a complex interconnected grid system, "The Interconnect", supplying power to millions of people at the flip of a switch is indeed a marvel of technology, if not a miracle. Unlike natural gas, petroleum, and nuclear materials,
alternating current [AC] electricity is not a commodity. Electrical energy, except in the electrostatic form, neither exists in nature as other sources do nor can it be utilized directly. It is a means to transport energy found in fossil fuels, nuclear materials, flowing waters, blowing winds, and solar rays to homes, commercial buildings and factories etc. where it is converted to light, heat, mechanical, and chemical forms of energy for utilization. That is, AC electrical energy is a transportation medium and not a commodity in itself. Over the last one hundred years, the world has adopted electrical conductors as the means to guide the flow of electrons from the source to the load and vice-versa. It is an alternative to trucks, trains, and hydraulic or pneumatic pipes. The transmission line infrastructure, to some extent, resembles the highway infrastructure with electrons resembling oil and petroleum tanker trucks or a system of pipes for natural gas and water supply or sewage collection systems. Just as fluids and gases flow from a higher pressure at one end of the pipe to a lower pressure at the other, electricity flows from a higher potential at one end of the wire to a lower potential at the other end. However, unlike the pressures in fluid and gas pipes, the electric potentials can be reversed instantaneously causing flow of electricity to reverse. Just as infrastructures of highways and rail lines, though permanent, need to be upgraded to keep up with ever changing population centers, electrical power grids should also be upgraded continually. As the world tries to address the environmental challenge of our times through integration of wind and solar sources for the production of electricity, a globalized power grid structure [GREG] must be created through a carefully designed HVDC network.
4.2 Integration 4.2.1 Transmission Lines GREG will require hundreds of long distance transmission lines, including undersea cables. HVDC has been shown to be the technology of choice for distances greater than 600km due to several advantages: • Removal of the reactive power component, leading to; o Voltage quality enhancement o Superior power flow control • Higher power capacity per line (> 6 GW) • Smaller physical footprint • Higher efficiency/lower losses when compared to ultra high voltage AC • Economics of high temperature superconductors needs to be evaluated During the past decade, China has emerged as a world leader in domestic transmission expansion using HVDC. The country had installed 7,400 kilometers of HVDC line as of 2011, with the network in constant growth. The China State Grid Corporation plans to erect the world’s first 1,100 kV dc lines, three of which will originate in Xinjiang Province.
4.2.2 Implementation: Underground Bipolar HVDC Optimal corridors for HVDC from engineering planning do not often match available rightsof-way. Populous load centers, in particular, rarely have ample space for new transmission feeds. One solution to this dilemma lies in widespread use of underground HVDC lines. Though the cost of drilling for underground lines may exceed the cost of transmission towers, there are key advantages to underground HVDC: • Allows for optimal geographic placement • Safer from the elements; wind, water, ice, trees • Virtually maintenance free
Bipolar HVDC is recommended for both above ground and underground lines. The topology uses two conductors per line, in opposing polarity. The benefits of bipolar transmission when compared to monopolar are: • Reduction in losses as each conductor carries half the required current • Fast, smooth reversals in direction of power flow • Built-in redundancy: can act as monopolar when one conductor faults • Using 2 series-connected converters per pole, only ¼ capacity is lost during converter failure . • Power electronics converter/inverter costs are minimized. • An efficiency analysis for use of superconductors  would be highly desirable.
4.2.3 Building the Grid: Size and Scope National policies which support investment in new transmission are crucial to the development of cleaner, more efficient systems. Sharing of energy across political borders is the logical next step in creating an improved energy paradigm. Under direction from IRENA, international agreements may be created that facilitate renewable energy networks. Ultimately, regional, nationwide and multi-national grids will combine to create the global grid, offering reduced carbon emissions while minimizing energy storage requirements. Any regional endeavor into HVDC must be carefully planned for in order to provide both immediate benefits and potential for future connectivity into GREG. A recent study looked at New York State, which has an approximately 30GW peak load. Results indicate that the state, as a region, is too small for efficient implementation of HVDC: New York would need to plan along with neighboring states and construct a wider regional grid.
NYS ac vs. dc transmission efficiency
90 85 ac
dc 75 70 65 60 0
Total Real Power Produced (MW) Figure 2: New York State transmission efficiency, conventional ac vs. HVDC
4.3 Storage Methods To guarantee load balancing in a global grid, energy storage facilities must be constructed at select points within the network. Existing storage technology includes: • Pumped Hydro: Potential energy stored in reservoir above turbine • Hydrogen Fuel Cell (HFC): Chemical energy released and converted to electrical as hydrogen binds with oxygen. • Compressed Air Energy Storage (CAES): High pressure air stored most often in underground caverns. • Battery Banks: Conventional lead-acid battery storage, sodium sulfide or other electrode battery storage • Superconductors: Magnetic field energy storage in a super-cooled environment • Supercapacitors: Porous carbon electrode capacitors offer high density storage • Flywheel Storage: Rotating disc stores mechanical energy within a vacuum.
4.3.1 Reduced Storage Requirement in a Global Grid With greater extent of integration among global intermittent sources, the energy storage requirement will be lessened. SUNY at Buffalo’s Wind Power Study, which places hypothetical 3MW turbines at select locations during an arbitrary sample month, offers an indication of the reduced storage requirement.
Figure 3: Three Region Wind Study, China Wind Power Map
3-Region Wind Power March 2008 1400
1200 1000 800
0 1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728293031
Day Figure 4: Three Region Wind Study, average power produced Table 1: Three Region Wind Energy Storage Requirements [12,13] Energy Storage Nation/Region Produced (MWh) Required (MWh) % Storage China 242 7.3 3.0 Russia 212 14 6.6 Scandinavia 218 22 10 3 regions 224 8.7 3.9 When operating separately, China, Russia and Scandinavia would have to store 6.4% of all wind energy generated. Together, the three regions need to store 3.9%, a reduction of 2.5% or 5.6 MWh/turbine-month.
4.3.3 Centralized Storage For any extent of grid integration, an all-renewables grid will still require some amount of energy storage. Suppose, for example, that in the near future 20TW of renewable power capacity has been installed worldwide. At 20% average capacity, a 3% storage requirement suggests 900 million MWh deliverable monthly. The storage strategy proposed by Jacobson and Delucchi is a disbursed scheme, with each individual power plant storing hydrogen when generation is in excess; hydrogen is then shipped from the plant to satisfy transportation and industrial needs . Alternatively, a centralized storage strategy places megaplants at optimal locations within the worldwide grid, storing energy when generation is in excess and delivering energy when generation is lacking. The advantages of centralized storage are: • Shared resource removes storage requirement from individual generating stations • Economies of scale may reduce cost • Not reliant on development of a parallel market (e.g. a hydrogen market)
Facilitates storage for offshore wind plants Reliability: Centralized dispatch simplifies load balancing
4.3.4 Implementation: Pumped Hydro and Fuel Cell Megaplants Installing energy storage is largely dependent on geography and geology. All available storage methods will be employed where appropriate (e.g. CAES where there is a naturally occurring canyon). One strategy for completing the bulk of the system uses pumped hydro storage where water resources are plentiful and modularized fuel cell plants in other areas. Hydroelectric power plants will need only to modify their dispatch schedules in order to serve a storage function. And pure pumped hydro storage plants, despite their high cost of construction, offer massive potential in terms of quantity of energy retained. The 1.16 GW Blenheim-Gilboa plant in US’ New York State, for example, averages about 3.7 million MWh per month in energy delivered . China as a whole has more than 17GW of installed pumped hydro storage capacity, with 31 GW expected by 2015 . World regions most abundant in water, such as Scandinavia, can expect to have all storage needs met via pumped hydro. For areas with scarce water, modularized fuel cell megaplants can be placed at optimal or nearoptimal locations, dependent on land-use rights and topology. The advantages of fuel cell storage include: • A dc power signal out (to a dc grid) • Low conversion losses due to a single conversion from chemical to electric • Reliability when implemented redundantly with n+1 or greater modules Excess energy will electrolyze water and produce a reserve of hydrogen, to be used as fuel when demand peaks above supply. For example, a bank of 116 2MW Molten Carbonate Fuel Cell (MCFC) modules is installed to create a 230MW plant. Should the plant deliver energy at a 10% average capacity factor, it will supply 17,000 MWh/mo.
Conclusion In addition to Asian, American and European contributions, South America and Africa are also expected to play a significant role in creating a Global Renewable Energy Grid. Brazil, Argentina and Peru have each shown innovation in cost sharing and pricing schemes that support sustainable sources. And Saharan solar power promises to provide trillions of MWh of energy. At the same time African development and growth of cities will augment the continent’s role as a consumer. As the world’s nations continue implementing their own bottom-up strategies for transition to renewable energy, a centralized, top-down regulation and approval process must emerge to bind them together. While each nation will be responsible for funding its internal infrastructure, wealthier countries and international development banks will need to support power industry reform in less well-off regions. Researchers in both industry and academia must also come together across political bounds, combining the best elements of long-term energy planning into a unified global vision.
References  Christian von Hirschhausen, “Developing a Super Grid: Conceptual Issues, Selected Examples and a Case Study…”, Dresden University of Technology, 2010.  Mark Z. Jacobson and Mark A. Delucchi, “Providing All Global Energy with Wind, Water and Solar Power, Parts I and II”, Energy Policy 39, p. 1154-1190, 2011.  Rosana Francescato, “How Clean Energy Victory Bonds Can Power Our Future”, Aug. 28, 2013, Available: www.renewableenergyworld.com.  E. Kader, M. Safiuddin; "The US and European Electric Power Grid Organizational Structures"; Term Paper for EE730; Univ. at Buffalo; Dec. 11, 2003.  IRENA, Institutional Structure, Available: www.irena.org  Robert Finton, “Regional HVDC for All Renewables Networks”, State University of New York at Buffalo, September 2014.  Naomi Klein, “This Changes Everything” , Simon and Schuster, 2014.  “The ABCs of HVDC Transmission Technology”, IEEE Power and Energy Magazine, Vol. 5, No.2, March/April 2007.  M. Lemes and W. Breuer, “UHV DC 800kV Bulk Transmission”, presented at IEEE T&D Latin America, Sao Paolo, Nov. 2010.  Jon Moscovic; “High Temperature Super Conducting Cable Solves Many Electrical Infrastructure Problems”; M. Eng. Project; August 2006.  Kang Chongqing, et.al., “Balance of Power”, IEEE Power and Energy Society Magazine, Sept./Oct. 2013, pp. 56-64.  Robert Finton, “Global Energy Grid Project: China Feasibility Study”, STS International, August 2011.  Padmavathy Kasthurirangan, “Wind Energy Essentials: Russian Supergrid”, Univ. at Buffalo, Fall 2010 Dr. Mohammed Safiuddin is Research Professor Emeritus at the State University of New York at Buffalo and President of STS International, an engineering consulting firm in Amherst, NY. Robert Finton is a Ph.D. candidate in electrical power systems at the State University of New York at Buffalo. .