Published on April 28th, 2014 | by Roy L Hales35
What Can We Do About Grid Loss?
April 28th, 2014 by Roy L Hales
The world’s transmission lines are believed to have dropped approximately 1.4 trillion kilowatt-hours of electricity last year. That’s around 1.2 trillion metric tons of CO2 dumped into the atmosphere. Though it is unlikely these loses can be eliminated in the near future, there are ways to reduce them.
Losses of 5–7% or so are the norm today in the United States, BC, and Ontario.
Capgemini, one of the world’s foremost consulting firms, has been working with Ontario Power Generation since 2001. Larry Rousse, Director of Utilities at Capgemini, said, “The approximate amount of Transmission line losses in the Ontario system is 6.5%. Transmission losses do vary pending the demand on the system. Losses occur as a natural phenomenon when electricity is transmitted between two points. The physics of electricity means that losses rise exponentially as the current on a circuit increases. For the electricity grid, this means basically that losses are highest when power consumption or when the demand is the highest. On an Ontario system with ~29,000 kilometers of transmission line, losses can be over 1000 MW (the size of a Bruce nuclear unit).”
The transmission losses appear to be slightly less on the West Coast. According to Mora Scott, of BC Hydro, they work out to about 5%:
“For fiscal 2013, line losses were 5,159 gigawatt hours, which represents approximately 10 per cent of domestic requirements. These figures are for the total amount of losses and system use, including legitimate technical losses on both the transmission and distribution system as well as theft. Transmission losses represent roughly half of this total and can vary greatly in any given year due to factors such as the volume of energy imported or exported and the amount of energy generated in the plants.”
Utilities engineer Bill Powers says the Sunrise Powerlink, which carries energy from renewable projects to San Diego, loses an average of 7–8% and on a hot day it can rise to as much as 14%.
According to Environment California’s report Shining Cities: At the Forefront of America’s Solar Energy Revolution (p 14), “Many cities depend on electricity transmitted from hundreds of miles away to meet local needs. Roughly 5 to 7 percent of the electricity transmitted over long distance transmission lines is lost. Distributed solar energy avoids these losses by generating electricity at or near the location where it is used.”
“Having the generation as close to the load center as possible, reduces losses due to the reduced requirement to transport generation over long transmission lines,” Rousse said.
Powers has been arguing this for years. He believes that San Diego’s power needs could be satisfied by developing 2/3 of the city’s rooftop solar potential. As only 2% of this potential is presently being utilized, there is a great deal of room for the industry’s expansion.
Southern Californian cities like Los Angeles, San Diego, and San Jose – where the solar panels on some homes produce more power than they need – are leading America’s development of this technology.
Solar has not been as productive in more northern latitudes. Egles said his home, in Victoria’s suburb of Oak Bay, obtains 40% of its energy from solar panels. A house in Kamloops BC draws 75% of its power from solar. Some homeowners in the rain forests of BC and Washington state have been told, of course, that there are too many trees around their houses. They would need to cut them down to increase the amount of available sunshine before considering solar — not a logical option.
Egles said Ontario’s rooftop solar industry has developed to the point that you cannot drive a mile without seeing an array installation, but he did not suggest it could totally replace conventional energy sources.
On page 5 of his 2007 study, The Potential for Solar Electric Power in British Columbia, Egles wrote that rooftop solar could supply 53% of the province’s residential needs.
Environment California claims (p 36) that every one of America’s 50 states has the potential to generate more electricity from the sun than it uses in an average year and in 19 states the solar PV potential exceeds demand by a factor of 100 or more. They include Washington state among those where the potential exceeds demand by a factor of at least five (figure 7).
Only they did not expand upon this topic sufficiently for the reader to know if this an unattainable potential – that might, for example, require the entire nation to be transformed into a solar farm – or an attainable goal.
Both Rousse and Scott perceived renewable technologies (wind, PV, hydroelectric, & biomass) as components in a larger picture.
Rousse added that, “Other factors such as volt var optimization (VVO) offer new methods of reducing the voltage or managing the voltage closer to the margin on the distribution systems. Lower voltage levels on the distribution system reduce the overall demand thus having a positive overall affect.”
His company, Capgemini, is helping BC Hydro implement a smart meter system. Scott explained that while this does not prevent grid loss, it will cut down on the amount of wasted energy.
“Normally, BC Hydro pushes out more power from our generating facilities, at increased power loss, to ensure you have quality power when you need it,” he said. “Smart meters provide the final ‘at-the-home’ voltage information that BC Hydro previously did not have access to. This information allows us to manage the amount of electricity delivered from each of our facilities so that we are only pushing through what is needed.”
“While smart meters help to reduce wasted electricity, they do not help us eliminate electricity loss. Loss will continue to increase as demand for electricity increases – line loss is proportional to demand. Also, with or without the smart grid, electricity will still need to be transmitted over long distances and because of this, loss will occur.”
This raises another important question. Most electricity is carried through HVAC power lines. In Europe, where Capgemini does a large part of its business, they have been experimenting with HVDC power lines for decades. Power losses are said to be as much as 30-40% lower than with HVAC lines, but this technology also requires rectifier stations that are considerably more expensive.
Scott said, “If BC Hydro were considering expanding our system to transport significant amounts of electricity, BC Hydro would consider HVDC lines as an option. We always evaluate all of our credible options.”
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