Yeah, we gotta build some of that solar and wind stuff, but lets just look at the savings we realize just by building HVDC trunklines in the US, without renewable energy. An AC transmission line has a 7% transmission loss, DC has a 3% transmission loss.
Lets say we want to move 200 gigawatts of electricity 1000 miles. Using an AC transmission grid we lose 14 gigawatts. DC transmission lines see only a loss of 6 gigwatts. So on paper if we switch from AC to DC in this case we save 8 gigawatts. The Equivalent of 8, 1000Mw nuclear power plants or 8, 1000Mw coal burning plants.
8,000 Mw of coal fired plants equals the carbon footprint of 9.6 million cars.
8,000 Mw of coal fired plants will emit 59.2 million tons of Co2 in a typical year, including 2720 pounds of mercury and 3600 pounds of arsenic.
In this scenario just switching to HVDC saves nearly 60 million tons of Co2, thousands of pounds of mercury and arsenic. Plus its cheaper, it saves money. In 3 years GE might have its new class of offshore wind turbines ready ... in the 10 to 15 MW class. Using MRI type magnets these turbines might make wind the cheapest form of electricity on the planet.
Does this seem absurd to you? There must be a hook to this, right ? HVDC must cost a lot or some part of a HVDC system makes it unpractical. Nope.
As long as the installation is longer than about 50 miles, HVDC transmission lines are cheaper. You've all seen paths cut thru a forest with the towers and wires strung from tower to tower ? AC power is 3 phase, and a ground or neutral, making a total of 4 wires. DC, 2 wires. Where AC needs two sets of towers and 2 sets of wires, DC can transmit the same amount of power thru one set of towers holding 2 wires.
HVDC is suitable for transmission of as much as 2 gigawatts of electricity, Ultra High Voltage DC as much as 7 gigawatts of electricity. As part of the Euro supergrid undersea HVDC cable will connect the UK, France, Germany and Norway, while providing a undersea backbone for wind power development.
Off the East coast of the US, there is a similar project that should be started in a about a year. A 350 mile long HVDC trunkline from about Sawyerville New Jersey to Virginia Beach Virginia called the Atlantic Wind Connection. The purpose is to allow wind developers to install offshore wind turbines 12 to 18 miles from the shore, out of sight. and not have to build individual transmission systems to move electricity to land.
In 3-4 years GE might have its new class of offshore wind turbines ready ... in the 10 to 15 MW class. Using MRI type magnets and composite materials these turbines might make wind the cheapest form of electricity on the planet.