Despite this current flowing back and forth many times a second, the energy still essentially flows continuously from the power plant to the electronic devices. A major advantage of alternating current is that its voltage can be modified relatively easily using a transformer , which allows power to be transmitted at very high voltages before being taken down to safer voltages for commercial and residential use.
As seen in the first equation, the power lost through transmission is proportional to the square of the current through the wire.
Therefore, it is preferable to minimize the current through the wire so that the energy loss is reduced. Of course, minimizing the resistance would reduce the energy lost as well, but the current has a much larger impact on the amount of energy lost due to its value being squared.
The second equation shows that if voltage is increased, the current is decreased equivalently to transmit the same power. Hence, the voltage through transmission lines is very high, which reduces the current, which in turn minimizes the energy lost through transmission. This is why alternating current is preferred over direct current for transmitting electricity , as it is much cheaper to change the voltage of an alternating current.
However, there is a limit at which it is no longer advantageous to use alternating current over direct current see HVDC transmission. Most devices large factory dynamos for example that are directly connected to the electrical grid operate on alternating current, and electrical outlets in homes and commercial areas supply alternating current as well.
Devices that require direct current, like laptops, usually have an AC adapter that converts alternating current to direct current. Alternating current is the current of choice globally as it has many clear advantages compared to direct current. And both are very timely inventions which I sincerely believe are critical enablers for a supergrid. Neat stuff. You may want to back end it through end users of DC power systems ranging from batteries to renewable power to electrical components and generation like Emerson and GE.
Or even EV developers and manufactures. Nonetheless good luck dealing with the Swiss or god forbid the Swedes ;. For a case in point, see:. The argument goes that burried power lines are better for infrastructure security. We all know that after every major hurricane, snow storm, etc the power company has to scramble around to fix the downed lines.
But this reason is distinct from the economic argument for long distance transmission. You mentioned that over 40 miles for HVAC is impractical, but is this a function of the voltage? Can local distribution through burried AC lines then be practial? As far as I know, no one has advocated for DC distribution up to the substation or household level, and that would likely be unworkable anyway.
Does DC have any place in distribution, or is the discussion limited to large interconnects for the forseable future? If not, would there always be some intermediate level voltages that are too local to be DC, but too high voltage to bury as AC, so then they would be impossible to bury with current technology?
All good questions. I do think the capacitance problem would limit distribution lines just the same as transmission lines; however, this is not a practical limitation, since the distribution grid from substation to consumer is only rarely greater than 40 miles long, and that would only be in very rural areas. In cities there are many substations, and lines from the substation to the consumer are rarely longer than about 10 miles.
The bit about infrastructure security can go both ways, because overhead lines are generally easier to repair than underground lines. I hear from industry insiders that at least from an engineering point of view the fact that underground lines typically take 40 times as long to fix as an overhead line no exaggeration! Incidentally, rapid repairability is a key feature of elpipes , which are unique among power lines in that they have a train-like mobility within their conduits, which are essentially similar to a gas pipeline which re-risks the cost of installatrion, because we know very well how to build gas pipelines.
As to the possibility of DC distribution: it is happening now on board the most modern cruise ships , in data centers , at remote mine sites, and in some other microgrids as well. The growth trajectory of DC power distribution is quite high, but starting from a small base; ABB is the clear market leader. I do expect there will be examples of DC power distribution in some communities with high penetration of solar power in the near future.
Yes problem skin effect it in a high alternating voltage is always present, this increases the diameter of the conductor in the form of a tube, but there was the problem of shielding and radiation losses. But DC is considered, the maximum current density is concentrated within a conductor, in this case brings to the fore the problem of organizing sverhprodyaschego conductor already have a model with effect it atC.
For AlanR In Russian underground high-voltage grid, from the outset, for the safety of industrial facilities in the event of war, particularly nuclear, and only then to improve the energy infrastructure.
Infrastructure originally designed centralized, with standardized parameters of generating capacity and transmission lines. The problems of non-synchronization AC 3-phase C-aligned ballasts and reactors ban non-synchronous switching loads. The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.
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Silver Spring, Maryland. Braintree, Massachusetts. Columbus, Ohio. Energy Solutions Multiple Locations. Transformers change the voltage while capacitors and inductors keep the wave form in sync. Effects of inductance and the changing loads can put the AC waveform out of sync, which ends up in loss of efficient transmission. Above: HVDC makes it easier to cross bodies of water. Peak Voltage: AC lines are designed for peak voltage, in DC power you can carry twice the power at steady DC voltages which would be the same as only your 'peak' AC voltage.
So in other words you fit more power on the same cable. Radiation and Capacitive Loss: AC power radiates and there is some capacitive coupling to the ground and in between the 3 conductors. This reduces efficiency. HVDC doesn't have this problem. Skin Effect: AC high voltage often uses clusters of wires or cables because of this phenomena, however HVDC can have just one large cable which can be cheaper. Superconductors: If we use superconductive conductors in super cold temperatures we can deliver power through underground cables with almost no loss at all.
Unfortunately this technology is not yet cost effective. Above: cross section of superconducting tape wire. Superconducting wire is designed by engineers specifically for the given use. Wireless Power Transmission It is possible to send power wirelessly through the air. Nikola Tesla and the General Electric Research Lab experimented with this, however it is impractical for a number of reasons. It is extremely inefficient going through the medium of air, and it is deadly for animals like birds passing through the high powered beams.
It is unlikely this technology will ever be useful, especially since we are leaping ahead with HVDC, achieving impressive levels of efficiency.
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