The most prolific Serbian genius Nicola Tesla, in the infamous War of Currents defeated Thomas Alva Edison, the legendary inventor of the west during 1890s! After a century, the ghost of Edison’s DC transmission system is revitalized again with an uncountable prospects for future power generation for the humankind! With that then declared obsolete little DC wizardry and a lot of investment of today’s (but quite rational), we can now realistically dream of swapping green power across continents! Reports abound of homeowners and businesses unplugging from the power grid and opting instead to generate and store their own electricity. Such grid defections may make sense in places where electricity rates are sky-high or service is spotty. However, for just about everywhere else, it is far more sensible to do the opposite: interconnect regional electricity networks to form a globe-spanning hypergrid.
What makes this idea so compelling are the major strains on today’s power grids: soaring energy demand in fast-growing megacities; rapid expansion of carbon-free but intermittent wind and solar power; and the ever-increasing need to secure grids against electronic and physical attacks. The smaller and more isolated a power network is, the more difficult it is to maintain the nearly instantaneous balance between electricity supply and demand.
Nevertheless, the technology now exists to transmit massive amounts of electricity over long distances without significant losses, thereby allowing operators to balance consumption and generation across an entire continent—or, potentially, the globe. If an outage occurs in one country, the sudden change in line voltage and frequency could trigger a generator thousands of kilometers away to compensate for the shortfall. Similarly, if the wind in a normally wind-dependent area dies, electricity from its neighbors could rapidly fill in. Alternatively, if one region is experiencing heavy rainfall, hydroelectric dams there could capture the energy, to send elsewhere as needed. A hypergrid would ensure that all or nearly all the electricity that is generated would get consumed, thus avoiding such wasteful practices as paying wind-farm operators to curtail production or dumping energy that’s not immediately needed. (To be sure, storing excess energy would also help avoid such problems, but large-scale economical energy storage is still not widely available.)
One of the ardent constraints of harvesting green energy is the diverse localization of its abundance. Solar energy, being the king among renewable sources, is distributed around the globe so erratically and unevenly due to climatic variables that the average solar energy available for use after power purposes in a demarcated zone is not considered consistent and reliable enough yet. At night, the sun is down, clouds often cover it up, at dawn and dusk the intensity is beyond usability. Only 3-4 solar hours are there for optimum use. The scenario is even disappointing in polar states where the sunlight is always dimmer than that of tropical, sub-Saharan or Arab regions. On the contrary, in places like deserts where insolation is abundant around the entire year, millions of acres of land permanently dried to barren and residence of no people. Only the available solar energy from five tiny dots on five deserts of earth can fill up the demand of 18 terawatts of total worldwide energy demand. But the problem is solar power is not intermittent when one side of Erath is facing the sun, the other is in dark. Therefore, a continuous global energy network is needed to be established to overcome the inconsistency of solar power originated from the earth’s rotational motion. For example, the time difference between the Taklamakan desert and Bangladesh is three hours. When the sun is down in Dhaka, the capital of Bangladesh, the desert is still enjoying sun-shower. So, if these two regions can be connected through the global energy network, Dhaka can purchase energy from China to light up themselves. When the Taklamakan is in dark it has to seek power from the farther east zone like Tasmania or Arizona, which is yet to get under dusk at the same instance. The sunny zones will light up the nightly ones. No extra storage devices like batteries will be needed. For this purpose, some points on earth are to be located where solar collectors will be installed for the optimum adjustment and balance of energy flow through the global network. Things are to be working like a domino way; the regions will light up one after another with the rotation of the earth! The spatiotemporal dispersion of renewable plants will smoothen the variability of energy flow from erratic resources to the most desired level and eradicate the reliability problem of such green power permanently.
The global energy grid may also include other sources like wind, geothermal, hydro, tidal etc. For harvesting wind energy, the roaring forties and other windy locations are to be especially underscored. Land areas often have frequent obstacles that not only reduce the wind velocity but also make it erratic. It can be optimized by installing turbines on sea surfaces where wind flow is much steadier. The Roaring forties zone has the ability to deliver highly consistent wind force to rotate the turbines. But the problem is most of the zone is covered by the oceans. To overcome this challenge, we need to use large pontoons or rafts, on which thousands of wind turbines are to be installed. They would be anchored to the ocean beds with proper marine techniques. The transmission can be made possible along floating pontoons connecting to each other or submarine cables like optical fiber internet network. If needed the power poles may be erected on similar floats and power can be transmitted towards the ground. This may be required to smoothen up the shipping trails near the harbor. Geothermal sources need many complicated accessories to convert power making it harder to handle and maintain, unlike solar or wind technology. Still, they can be used in local premises since they can deliver intermittent flow.
The submarine internet cable network is great evidence of global data transmission and communication made possible by human around the entire world connecting all the states. In a similar fashion, a global power reticulum can be weaved too and thus energy can be distributed intercontinentally. A tiny piece of sunny desert full of solar cells directly can light up a dark city apart from thousands of miles without any energy storage system. High Voltage DC power transmission has already been proved pragmatic and feasible for such kind of actions. Besides, with the progress of wireless energy transmission technology, we can be aspiring for a revolution in transferring energy without any cable within the next thirty years. If that is made possible, the green dream of a global energy network is a matter of time only to come true. In general, a global hypergrid would allow power to be generated far from population centres. For instance, some of the world’s best sunlight can be found in the sparsely populated region south of Darwin, Australia, where it is estimated that all of that country’s energy needs could be supplied from a solar farm the size of a cattle station. With an undersea link to Southeast Asia, that electricity could also be dispatched to countries like Indonesia, Papua New Guinea, and Singapore. Moreover, with a hypergrid in place, operators could significantly scale back their spinning reserves—backup capacity that they can tap if demand spikes but in practice is rarely used.
So what would it take to build a global hypergrid? Technologically, it would hinge on a globe-encircling network of high-voltage direct current (HVDC) transmission systems, most of the components of which already exist. Beyond that, regional grid operators would need to agree on how to pay for such a network, establish rules for trading the electricity, and specify the technical codes and standards that will allow the hypergrid to operate safely, reliably, and securely.
The roots of the global hypergrid stretch back to the dawn of the power industry, when the “war of the currents” raged between the era’s two great inventors: Thomas Edison and Nikola Tesla. In 1882, Edison demonstrated the first commercial electric power plant, which was based on direct current. Nevertheless, Tesla’s alternating current would rule the day.
In 1895, Tesla’s dream of generating electricity from Niagara Falls was realized, and within a few years that energy was electrifying New York City, 700 kilometers away, thereby proving the superiority of the AC system. Well into the 20th century, the world’s power systems were based on AC.
The key to AC’s triumph was that power could be transformed to higher voltages by use of magnetic induction and then sent over long distances at low currents, minimizing the losses due to resistance; at the destination, the system would reduce the voltage for local distribution. At the time, there was no way to do the same with DC. However, power engineers also knew that a DC system operating at high voltage would be superior to AC for the same task, because the amount of electricity lost during DC transmission would be far less than with AC.
How much less? Let us say you’re transmitting a given amount of power by high-voltage DC: When you double the voltage, you need only half the current of a comparable AC system, thus reducing your line losses by a factor of four. You also need a lot less wire, because DC current penetrates the entire conductor of a power line, whereas AC current remains largely near the surface. Put another way, for the same conductor size, the effective resistance is greater with AC, and more power is lost as heat. In practice, that means the overall transmission infrastructure for AC far exceeds that for DC. To transmit 6,000 megawatts using a 765-kilovolt AC system, for instance, you would need three separate single-circuit transmission lines, which would cut a right-of-way path about 180 meters wide. Compare that with an 800-kV DC system, which would require just one 80-meter-wide path.
HVDC also allows for the easy transfer of power between grids that are operating at different frequencies. The converters, cables, breakers, and other components for HVDC are more expensive than those for AC, so it only makes economic sense to use HVDC over distances of 500 km or more. But that break-even distance has continued to come down as the cost of DC components drops.
With these advantages in mind, power engineers experimented with DC transmission technology throughout the 20th century. The key building block for HVDC was and still is the converter, located at either end of an HVDC line. It serves to convert high-voltage AC to high-voltage DC and DC back to AC. Through the 1960s, such converters relied on mercury-arc valves, which were basically electronic switches that could only be turned on and not off, thereby limiting their functionality and resulting in substantial losses.
In the 1970s came the next advance in DC technology: water-cooled thyristors, a type of giant solid-state switch that can be turned on and off. The first ones were demonstrated in 1978 at the Nelson River HVDC Transmission System, which sent power from hydroelectricity stations in northern Manitoba, Canada, to the country’s populated south.
Since then, HVDC has spread only modestly in North America, but it has taken off in other parts of the world, most notably Brazil, China, India, and Western Europe. Starting in the late 1990s, these newer HVDC deployments have relied on insulated gate bipolar transistors (IGBTs), which are specialized transistors that can be switched many times per cycle. In the latest IGBTs, the gates can open or close in less than a billionth of a second.
Today’s HVDC converters are known as voltage-source converters (VSCs). Although traditional converters continue to be used for higher-voltage, higher-capacity transmission, VSCs make it easier to integrate HVDC lines into existing networks. The VSC concept was first demonstrated in March 1997 between Hellsjön and Grängesberg, Sweden, at a modest 3 MW and 10 kV. Five years later came the first sizable VSC installation: the Cross-Sound Cable project in Long Island Sound, between New York and Connecticut. That project had a moderately high rating of 330 MW, but conversion losses were also high, at 2.5 percent. With the latest VSCs such losses have been cut to just 1 percent.
What’s more, it is now possible to have multiple terminals along a single HVDC line, so that you can tap into the line at intermediate points, rather than just at the end. By moving beyond point-to-point HVDC transmission, you will be able to connect the lines into a mesh, which of course will be more complicated to control but potentially more robust and incessant. Direct or indirect, most of the global crises and conflicts are still arising actually from energy issues. In this nexus, Global Energy Network can be an essential tool to promote mankind brotherhood all over the world since it will establish an energy dependency among the nations to each other. No country will risk blackouts by jeopardizing diplomatic relations which indeed will promote the environment for global peace that mankind always dreamt for.
The global energy network is enough to be based on two green sources namely solar and wind. Even though the only solar seems more than enough, wind can be a reliable auxiliary backing against all odds. Other resources like tidal and geothermal can be added to localized preferences too. Considering all factors and parameters, this network is quite possible to realize within a couple of decades or even less. Now, the only thing needed is a global momentum in favor of this noble objective. All the political and technical leaders around the world are welcomed to think over the matter for the sake of a greener and sustainable mother earth making it livable for its children. Let us get one for the greenest earth ever!