Following the Western Energy Crisis of 2000 and the Major East Coast Blackout of 2003, a group of engineers in California got together to design a new type of bare overhead conductor that could carry twice the current of a conventional conductor without exhibiting excessive conductor sag. The team essentially replaced steel core strands, used to strengthen most types of overhead conductors, with a composite core made up of high-strength carbon and glass fibers.
The composite core offered a coefficient of thermal expansion nearly ten times less than steel. This allowed the ‘new’ conductor to carry very high levels of current during peak load and/or emergency conditions without sagging into underbuilt lines, trees or other structures. To date, the new conductor has been deployed to more than 400 projects in 40 countries, primarily to increase the capacity of existing transmission lines.
Increasing line capacity offers several advantages. It can alleviate grid congestion allowing the grid operator to access the least expensive source of energy; it can improve grid reliability should an adjacent line fall out of service; and it can open up existing pathways to enable the distribution of renewable energy without having to build additional lines.
The downside is that this conductor type (ACCC) has been categorized as a ‘High-Temperature, Low-Sag’ HTLS conductor and engineers associate high temperature with extremely high line losses. And they are absolutely correct.
What is often overlooked, however, is the fact that this particular conductor design actually operates more efficiently than conventional or other HTLS conductors of the same diameter and weight under any load condition. The reason is quite simple. The composite core is so much lighter than its steel counterpart, that it allows the conductor to utilize 28 percent more aluminum without a weight or diameter penalty. The added aluminum content (and quality) reduces the electrical resistance of the conductor which serves to reduce line losses by 25 to 40 percent or more depending upon load level.
In North America, line losses are generally considered to be around 3 percent and the costs are simply socialized and passed through to the consumer. If you broaden the range of transmission to include sub-transmission and the higher end of distribution ~34.5 kV and above, the number may climb to 4 or 5 percent, but most people would still consider these to be very small numbers.
Stepping back for a moment, think about how efficiency is driving technical innovation in other industries. Boeing, for instance, developed the carbon fiber based 787 Dreamliner to reduce fuel costs, extend range, and increase airframe service life. BMW and other car companies are also using carbon fiber technology to improve performance and fuel efficiency. You may have also noticed that it’s becoming increasingly difficult to find a bicycle or a pair of skis that doesn’t utilize carbon fiber technology. Performance and efficiency go hand in hand.
How and Why ETESA is Working to Build the World’s Most Efficient Electric Power Grid
Interview between Dave Bryant of CTO and Mr. Ivan Barria, CEO, Empressa de Transmision Electrica, S.A., (ETESA) Panama
Bryant: We understand that ETESA – the leading Panamanian Transmission Utility – is securing public financing via the Bond market to rebuild and expand the transmission infrastructure in Panama.
Barria: Yes. Over the last several years Panama’s demand for electricity has grown at a rate of nearly eight percent annually. This has put tremendous pressure on our grid. Additionally, because we do not produce fuel locally, we are adding renewable generation resources to supplement our hydro facilities. We intend to export a percentage of the clean electricity generated to Costa Rica as well.
Bryant: What makes this Capital raise unique or different from other Government backed infrastructure projects?
Barria: In most cases infrastructure projects are paid for by consumers. While the cost of transmission represents a relatively small percentage of a typical electric bill, these costs do add up and we are often limited in what projects we can pursue – and in what timeframes – based upon cash flow constraints. By pursuing Bond financing we can accelerate project completion thereby providing improved services and reliability sooner rather than later, without overburdening the consumer.
Bryant: Where is the revenue coming from to support the financing and return on investments?
Barria: The agreement we have with the Panamanian government allows us to retain any excess revenue that is generated from efficiency improvements that drop system and line losses below four percent. By pursuing maximum efficiency we are able to show actual revenues and predicted revenues that are sufficient to cover the investment costs and provide good returns to Bond holders. We have currently secured $200 million with the help of the Bank of Nova Scotia.
Bryant: Will the funding of the Bonds have a detrimental impact on the electricity prices in Panama – are the rate payers accessed a premium to cover the loans?
Barria: Not at all. Improvements in efficiency, capacity, reliability and resiliency will not only reduce consumer costs, it will also allow us to deliver more power to our rapidly growing customer base. This will not only be reflected in lower electric bills, it will also help our society and economy grow and become more productive. Everyone wins, including consumers and investors.
Additionally, even though the higher performance products we purchase are more expensive than commodity products, we generally order products in bulk through multiyear contracts. We also use tenders to ensure we receive competitive bids. The bulk purchasing contracts not only help reduce our costs, they also help manufacturers plan their production strategies which can help them as well. Finally, leveraging zero to one percent financing via EXIM Bank, World Bank, and others in Japan, Korea and elsewhere, allow us to establish one year payment terms with our vendors so we don’t have to actually pay for the products until they are in service and the vendor’s don’t actually have to wait one year for payment.
Bryant: That is a very creative strategy. Can you explain a little bit more about the role transmission and related equipment efficiencies have in your plans?
Barria: We only purchase the most efficient products and technologies. We recognize that many organizations focus on purchasing the least expensive components including transformers and commodity wires, but we are driven to reach the highest possible levels of efficiency. ACCC conductor, for instance. We know it costs nearly three times as much as ACSR or AAAC, but its efficiency gains – not to mention capacity gains – pay for themselves in months. And this is considering new lines. As it relates to upgrading existing lines there is no comparison and the cost savings are immediate - as we would otherwise have to replace structures at a much higher cost and over a longer timeframe.
Bryant: This appears to be a very unique strategy and your goals of having the most efficient and reliable transmission system on earth are very aggressive. How did you define the path to reach this goal?
Barria: It’s simple. When faced with daunting challenges one must think outside the box. When I assumed the role as CEO at ETESA, there were a handful of people that couldn’t understand this. Today, our team is now the most progressive group I have ever worked with. It’s quite an exciting and dynamic time for us all which I’m sure others in our business can relate to.
Bryant: Thank you, Mr. Barria. It seems you have developed a very impressive and practical business model for improving grid efficiency and reliability. Perhaps others will take note?
Returning to the discussion of electricity, let’s consider investments made to improve the efficiency and performance of generators. Improved efficiency reduces fuel consumption, associated emissions and life cycle costs. It’s generally easy to justify a few extra up front dollars for substantial long term performance gains. Transformers and other equipment also benefited from technical advancements. Again, improved efficiency and reduced life cycle costs justified higher upfront capital costs.
On the consumer side, substantial improvements have been made to improve the efficiency of appliances. In many cases, utilities offered incentives to consumers to use more efficient refrigerators, air conditioning units and light bulbs because of the difficulties associated with building new generation and transmission. An outsider might think it’s a strange business model to pay customers to use less product, but all industries certainly have their share of issues.
In recent years, Smart Grid was envisioned. The idea here, simply stated, is to connect the ‘generation brain’ with the ‘appliance brain’ so they can work more efficiently. This might allow dishwashers, washing machines and other appliances (including electric cars), for instance, to tap the grid during off peak hours. This is all good.
But what about the wires themselves that connect everything? They essentially represent one-hundred year old technology and many of them have been in service for 50 years or more.
Getting back to the high capacity composite core conductor described above, let’s consider its efficiency aspects on a 345 kV line upgrade – as was recently completed by one of the larger utilities in the U.S. Keep in mind that improving efficiency was not a first tier goal. Increasing capacity for a growing market and ensuring reliability in a highly corrosive and weather event prone area were the primary objectives.
A line loss calculator using IEEE 738 methodology (and certain operating assumptions) estimates that the use of the composite core conductor will reduce line losses by 30 percent compared to the steel core conductor of the same diameter and weight that it replaced (Drake size). If we assume a 62 percent load factor and a peak capacity of 3,000 amps, the reduction in line losses would equate to 300,000 MWh per year.
As a basis for comparison, let’s consider the energy savings offered by a 100 watt equivalent LED light bulb replacement. The LED reduces electrical consumption by around 80 percent compared to a standard incandescent light bulb. Translated, the use of 12.5 LED bulbs would save 1 kWh of electricity per hour. 12,500 LED bulbs would therefore save 1 MWh. If we assume a 4 hour per day / 365 day per year light bulb utilization, it would take 2,568,493 LED bulbs to save 300,000 MWh of electricity. At a cost of $20 per LED bulb, the energy savings would translate into a capital cost of $51,369,863.
The composite core conductor (3 phase, double bundled), on the other hand, would cost roughly $14,000,000 (not including hardware and installation costs). While these and other project costs would certainly add substantially to this figure, it would be safe to assume that the conductor would not have to be replaced every few years like the light bulbs. If the LEDs had to be replaced once every five years, the cost of the energy savings would climb well over $400,000,000.
From an environmental perspective, based on the average CO2 emissions from all combined sources of electricity in the state where this project was completed, either investment choice would reduce emissions by approximately 200,000 metric tons of CO2 per year. Considering that the average car in North America emits 4.75 metric tons of CO2 per year, this would be the equivalent of taking 42,000 cars off the road for every one-hundred circuit miles of 345 kV conductor upgraded or every 2.5 million lightbulbs replaced. It appears that conductor replacement may be a significantly less expensive alternative.
Perhaps we should take a closer look at the wires themselves and consider how modern conductor technology and line loss reductions might cost-effectively help us reach a number of important environmental and policy objectives? If policy makers can find a way to incentivize the utilities that invest in these upgrades, everyone should win.
About the Author
Dave Bryant is Director of Technology at CTC Global Corporation in Irvine, California. Dave was a co-inventor of the patented ACCC conductor and ancillary hardware components. His 35 year background as a design engineer focused on the use of advanced composite materials in numerous industrial applications which helped expedite the development, testing, and commercialization of the ACCC conductor.
