Ultra High Voltage (UHV) Transmission Could be Our Renewable Energy Interstate

John Whitney AIA

John Whitney

By John Whitney AIA

The renewable energy transformation of the United States is confronted with two serious challenges: Addressing intermittency in power generation and transmitting low cost renewable power from renewable resource rich regions to the rest of the country. In just the past three years, China has taken the lead in development of ultra high voltage (UHV) transmission lines to address both of these issues. China’s elegant, simple, and cost-effective solution to these challenges is now being implemented in Brazil and India, but in the U.S. depressingly little activity on this front can be observed.

While viable renewable energy resources are available throughout the United States, certain regions are blessed with truly remarkable renewable assets: Solar power in the insolation intense Southwest, on-shore wind generation in the windy Great Plains, hydropower in the Northwest and Northeast, and deep enhanced geothermal in the West. With constantly improving technology and steadily dropping costs, renewable energy power generation is now cost effective in many regions of the U.S. However, apologists for the conventional power generation industry continue to argue that without aggressive incentivization and subsidies, power from renewable generation sources is just too costly for most of the country.

But, guilty secret number one of the nuclear and fossil-fuel fired generation industries is that in renewable asset rich regions, renewable energy has already achieved parity. According to the U.S. EIA AEO2011 (Energy Information Administration Annual Energy Outlook 2011), the minimum LCOE (levelized cost of energy) for new hydropower generation is a very low, $0.0585/ kWh. The minimum LCOE for new on-shore wind is $0.0819/ kWh and new enhanced geothermal is $0.0918/ kWh. All three can produce renewable power for less than new coal generation ($0.094 to $0.1362/ kWh), less than new nuclear generation ($0.1139/ kWh) and less or nearly equal to new natural gas combined cycle generation with carbon capture sequestration ($0.0893/ kWh).

Minimum LCOE’s for thermosolar CSP ($0.1917/ kWh) and solar PV ($0.1587/ kWh) are higher than fossil-fuel and nuclear generation but (and these are 3 crucial buts): The AEO2011 LCOE’s for renewable sources do not include any incentives, LCOE’s for conventional generation do not include any external costs, and renewable energy generation costs continue to trend down while conventional generation costs are rising.

Guilty secret number two of the nuclear and fossil-fuel fired generation industries is that we could fulfill most of our nation’s electricity demand from renewable sources in our asset rich regions if we had a secure and modern transmission grid to get that low cost clean power to demand centers.

One Big Problem: Aging Transmission Infrastructure with Limited Range

Our current aging, fragmented, and limited capacity transmission grid is slowly moving away from a network architecture with relatively few large, hierarchically connected, tightly synchronized energy resources supplying passive consumers. It is evolving toward a smart grid network able to support significant penetrations of highly variable distributed renewable energy resources mixed with large central generation plants, energy storage, and responsive users equipped with embedded intelligence and automation. This requires more than improvements to the existing system; it requires transformative changes in planning and operating electric power systems.

The problem is: Even as we implement the smart grid, we still struggle to get low cost electricity generated by solar power in Arizona to Chicago, hydroelectricity from Washington to Texas, geothermal power from Colorado to the east coast, and wind generated electricity from Nebraska to New York and California.

How ridiculous is the long distance transmission problem? As Matt Slavin in Renewable Energy World notes, Nevada has perhaps the highest solar energy potential in the nation. The U.S. Department of Energy (DoE) calculates that 10,000 square miles of Nevada land could supply all U.S. electricity needs with current commercial efficiency rates yet transmission lines in Nevada barely exist. A white paper jointly issued by the American Wind Energy Association (AWEA) and the Solar Energy Industries Association (SEIA) estimated that in 2009 up to 300 GW of wind projects faced potential deployment delays due to an inability to connect to the grid. For utility-scale solar in California alone, the figure was estimated at 13 GW in 2009.

In the U.S. our existing power distribution grid is severely limited by transmission capacity, currently topping out at the high end with 500 kV AC transmission lines. The electric transmission and distribution network is a very complex, very fragmented, poorly coordinated, and aging grid that supplies electricity to the country through 365,000 less than ideally coordinated circuit miles.

In a time of rapidly evolving technology, demand needs, and supply sources, it is horrifying to know that the majority of the existing grid infrastructure in the U.S. was constructed 30 to 50 years ago. According to the “National Transmission Grid Study” from the Department of Energy, 70% of our power transformers are over 25 years old and nearly 60% of the circuit-breakers are 25 years old. Transmission bottlenecks are common, we are severely limited in our ability to move power long distances, and we are beginning to struggle to balance power demand and with intermittent renewable power supplies.

The U.S. is a big country, but with maximum transmission limited to 500 kV lines (which waste about 7% of capacity in transmission) we are limited to transmitting electricity an absurdly short maximum distance of no more than 530 miles.

One Big Solution: Ultra High Voltage Transmission

We need a national scale ultra high voltage (UHV) transmission superstructure to overlay and supply the regional, state, and sometimes local transmission organizations that now make up our patchwork grid. 1,000 kV UHV transmission lines can send larger amounts of electricity up to three times further than traditional high voltage 500 kV lines, while also cutting electric “friction” losses by 25% to 40%. UHV can also reduce by 40% the amount of land required to construct the transmission lines. Sounds pretty good to me.

Researchers and engineers have pursued two options for UHV. One is UHV-DC power transmission, which has the double benefit of being able to transmit electricity at greater distances than AC lines with less power loss. However, DC lines are costly, requiring converter stations to convert the DC power to AC power before it can be distributed to utilities and consumers.

The other avenue of exploration is UHV-AC transmission, a technology that was first investigated in Canada in the 1960’s. Several test lines were built during the 1970’s in the U.S., but the most progress was made in the Soviet Union. However, interest waned in the 1990’s after the Soviet Union collapsed and power demand in Japan stagnated.

Driven by China’s ever-growing demand for power, both UHV-DC and UHV-AC transmission technologies are currently under development there. In China, UHV lines are being constructed to bring hydroelectricity from the distant southwestern provinces of Yunnan and Sichuan, and coal-fired power from the inland provinces to the power-hungry eastern urban centers.

So, what are the specific advantages that UHV can bring to the transmission grid? And, what would a UHV transmission superstructure allow us to do to expand and consolidate market penetration of renewables in the United States?

UHV Overall Advantages

Increased Transmission Capacity: A single 1000 kV UHV-AC circuit can transmit +/-5 GW, approximately 5 times the maximum transmission capacity of a 500 kV AC line. An 800 kV UHV-DC transmission line is even more efficient, with a capacity to transmit 6.4 GW.

Extended Transmission Distance: A 1000 kV UHV-AC line will economically transmit power distances of up to 2,000 km (1240 miles), more than twice as far as a typical 500 kV AC line . An 800 kV UHV-DC power line can economically transmit power over distances of up to 3,000 km (1,860 miles).

Reduced Transmission Losses: If the conductor cross-sectional area and transmission power are held constant, the resistance losses of a 1000 kV UHV-AC line is 25% that of the 500-kV AC power line. The resistance loss of an 800 kV UHV-DC transmission line is an even more remarkable 39% of typical line power erosion.

Reduced Costs: The cost per unit of transmission capacity of 1000 kV UHV-AC and 800 kV UHV-DC transmission is about 75% of 500 kV AC costs.

Reduced Land Requirements: A 1000 kV UHV-AC line power line saves 50% to 66% of the corridor area that a 500 kV AC line would require. An 800 kV UHV-DC line would save 23% of the corridor area required by a 500 kV DC line.

UHV and Renewable Generation Market Penetration

The United States is incredibly rich in potential renewable power resources. Just cherry-picking the low-hanging fruit of high value renewable resources with the lowest electricity generation costs finds nearly the entire country within reach of multiple renewable power sources if we can establish a UHV transmission grid. As an additional benefit, power from the overlapping renewable resources would even out generation fluctuations, addressing once and for all renewable energy intermittency issues.

Solar Generation: We have high insolation solar resources in the Southwest states of New Mexico, Colorado, Utah, Nevada, California, and Arizona. UHV-AC brings 75% of the country within range of these solar resources, from Seattle in the north to Chicago and Nashville in the east. UHV-DC puts the entire country within range with the exception of New England.

Wind Generation: High value wind resources extend from North Dakota to Texas, including South Dakota, Nebraska, portions of Iowa and Montana, Kansas, and Oklahoma. UHV-AC transmission from Great Plains wind farms would reach all of the U.S. with the exception of southern Florida and New England. UHV-DC lines would bring low cost wind power to the entire U.S.

Hydropower Generation: Hydropower resources are located throughout the entire nation, but are especially rich everywhere except for the Great Plains and Florida. UHV-AC transmission would bring the hydropower to the entire country.

Enhanced Geothermal Generation: High value, favorable deep enhanced geothermal systems (EGS) sites are located throughout the western states with particularly favorable resources in Colorado, Utah, Nevada, Idaho, Oregon, and Northern California. Much like high insolation Southwestern solar resources, UHV-AC transmission would bring 75% of the country within reach of low cost geothermal power. UHV-DC lines could reach every region except for New England.

So, What’s Going on in the Rest of the World?

While the United States continues to “drill baby, drill”, strip mine mountain tops, debate what to do with radioactive waste, and pump toxic chemicals into the Marcellus Shale, what is the rest of the world doing with UHV transmission technology? China, as noted earlier, has plunged into the development of UHV transmission. The State Grid Corporation of China (SGCC) notes that “China has achieved an overall breakthrough in UHV core technology and the localization of UHV equipment, with more than 100 domestic manufacturers and suppliers participating in the manufacturing and supply of UHV equipment.”

By 2020, the SGCC plans to spend $88 billion to establish a synchronized UHV power grid with the capacity to transit 300 GW over 56,000 miles of UHV line. Over 20 projects are planned, some of which are projected to cover routes of 1,240 to 1,860 miles. Examples in China include:

Jindognan to Jingmen (demonstration project), completed in January 2009: UHV-AC 1000 kV. 650 km (400 miles) from Jindognan to Nanyang and Jingmen. Cost: $835 million.

Yunnan to Guangdong, completed in 2010: UHV-DC 800 kV, 5-7.2 GW capacity. 1,400 km (870 miles), from southwest China’s Yunnan Province to large industrial centers in the Pearl River Delta in Guangdong Province.

Xiangjiaba to Shanghai, completed in July 2010: UHV DC 800 kV, 7.2 GW capacity. 2,000 km (1,240 miles). Cost: $440 billion.

Xilinguole to Jiangsu, starting construction in 2011: UHV AC 1000 kV. 1,435 km (890 miles). Cost: $4.91 billion.

Other global UHV projects include:

India: North-East Region to Agra, starting construction in 2011, completion by 2015: UHV DC 800 kV, 8 GW capacity. 1,728 km (1,074 miles). Cost: $1.1 billion.

Brazil: Belo Monte Dam to Southeast Brazil: Contract signed between SGCC and the Brazilian state power company, UHV, 11 GW capacity. 1,200 miles.

Meanwhile, Back in the U.S.A.

While the 2009 AWEA + SEIA white paper “Green Power Superhighways” proposed development of something much like what I have discussed here, I have yet to turn up any UHV projects actually planned for the United States. What passes for high capacity upgrades in the U.S. are projects like the 100 mile long Prairie Wind Transmission “extra-high voltage” 345 kV transmission line that has filed for construction permits in Kansas to “improve the regional electric grid by better integrating the east and west regions and facilitating the addition of renewable generation (the Flat Ridge Wind Farm) to the electric grid.”

I’m sure that this modest upgrade is a positive development for Kansas and immediately adjacent states. But it does nothing to bring low cost wind power from the Flat Ridge Wind Farm to Chicago or New York or Los Angeles. It is, however, emblematic of the fragmented, localized, and short-range planning that plagues the United States and frustrates development of a truly integrated national transmission grid. I don’t know about you, but I find this to be very disturbing.

We actually have a regulatory agency that can oversee the implementation of the transmission superstructure and more effectively manage the entire power generation network: The Federal Energy Regulatory Commission (FERC). FERC has, per the Energy Policy Act of 2005, the authority to locate interstate power lines and establish National Interstate Transmission Corridors. This authority was specifically mandated to offset current myopic state laws that severely limit new transmission development by requiring that development must provide benefits that accrue to providers and consumers within state borders. The Energy Policy Act of 2005 was designed to relieve congestion and serve the larger national interest (which needs some serious assistance).

Here’s the insanity: FERC’s ability to designate even just a few limited National Interstate Transmission Corridors (where we could efficiently run a national ultra high voltage transmission superstructure) has been tied up in litigation since 2007. FERC can and does site interstate natural gas pipelines but can’t do the same with power. Similarly, the Department of Transportation obviously has a mandate to develop the interstate highway system. But FERC can’t site a national UHV transmission superstructure.

And, therefore, we can’t build a national scale UHV transmission superstructure to supply low cost renewable energy to and to overlay the regional, state, and local transmission organizations/ utilities that now make up our 20th century patchwork grid.


A good article in Renewable Energy World nicely summarizes why the courts have overturned the EPAct 2005 designation of power to FERC to fast track high voltage transmission development. See:


Two problems were highlighted:

“We cannot accept DOE’s unsupported conclusion that its final agency action that covers ten States and over a 100 million acres does not, as a matter of law, have some environmental impact.” 9th Circuit Decision, p. 1965

The court also found that the transmission corridor designations would have a pre-emptive effect on state electricity planning, where consideration of a wide range of alternatives is typically required:

“Both the intent and impact of the NIETCs support the conclusion that they constitute major Federal action. They create “National Interest” corridors to address national concerns. The NIETCs cover over 100 million acres in ten States. Moreover, they create new federal rights, including the power of eminent domain, that are intended to, and do, curtail rights traditionally held by the states and local governments.” p. 1957

Point 1 (environmental impact) seems reasonable to me. Point 2 seems nuts. Yes, the EPAct 2005 is a major Federal action. Major Federal action is needed; that’s the point of the act!

What is particularly disturbing to me is that the EPAct 2005 went into effect in 2005. It took almost 6 years for this issue to be resolved (albeit poorly) in the courts. Meanwhile, our energy infrastructure languishes and the rest of the world moves ahead.

For more info see this FERC data sheet:

About the Author

John Whitney AIA is a registered architect with over 25 years of experience in all aspects of project development, design, management, and construction.  As Co-Founder and President of Taylor-Whitney Architects, his significant focus was on higher education clients and sustainable energy.  As the Founder and Principal of the Clean Energy Action Project, he now provides consulting services that include master planning, feasibility studies, and research in the realm of cleantech and renewable energy.  John is currently coordinating a solar PV database research project for AASHE (Association for the Advancement of Sustainability in Higher Education).

See all John’s articles.

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