What is the electric power grid, and what are some challenges it faces?

Last Updated: April 27, 2012

The grid of electric power lines has evolved into three large interconnected systems that move electricity around the country. Standards have been developed by the electric power industry to ensure coordination for the linked operations. Challenges facing the power grid include getting approval for corridors of land for new transmission lines within states or that cross multiple states, and the financing and constructing of new transmission lines to assure continued reliability of our electricity supply.

Getting electricity from power generating stations to our homes and workplaces is quite a challenging process. Electricity must be produced at the same time as it is used because large quantities of electricity cannot be stored effectively.

High-voltage transmission lines (those lines between tall metal towers that you often see along the highway) are used to carry electricity from power generating stations to the places where it is needed. However, when electricity flows over these lines, some of it is lost. One of the properties of high voltage lines is that the higher the voltage, the more efficient they are at transmitting electricity — that is, the lower the losses are. Using transformers, high-voltage electricity is "stepped-down" several times to a lower voltage before arriving over the distribution system of utility poles and wires to your home and workplace so it can be used safely.

Around the beginning of the 20th century, there were over 4,000 individual electric utilities, each operating in isolation. Almost all of those used low-voltage connections from nearby generating power plants to the distribution lines serving their local customers.

As the demand for electricity grew, particularly in the post-World War II era, electric utilities found it more efficient to interconnect their transmission systems. In this way, they could share the benefits of building larger and, often, jointly-owned generators to serve their combined electricity demand at the lowest possible cost, and to avoid building duplicative power plants. Interconnection also reduced the amount of extra capacity that each utility had to hold to assure reliable service. With growing demand and the accompanying need for new power plants came an ever-increasing need for higher voltage interconnections to transport the additional power longer distances. Over time, three large interconnected systems evolved in the United States.

Today, transmission and distribution lines owned by an individual utility are no longer resources to be used only by that utility. Electrical systems have been expanded and interlinked. The systems now provide the associated transport of electricity on the transmission lines where buyers and sellers may be geographically spread apart.

Close oversight of operations within the three power grids is needed to keep the various components linked together. The interlinked systems now include over 3,200 electric distribution utilities, over 10,000 generating units, tens of thousands of miles of transmission and distribution lines, and millions of customers.

Originally, each generating company was responsible for maintaining its own electrical system safety and planning for the future needs of its customers. Later, voluntary standards were developed by the electric utility industry to ensure coordination for linked interconnection operations. These voluntary standards were instituted after a major blackout in 1965 that impacted New York, a large portion of the East Coast, and parts of Canada.

Now, planning is done in a much more coordinated manner to achieve adequacy of supply, to establish and oversee formal operational standards for running the bulk power systems, and to address our Nation's security concerns for critical electrical infrastructures. All of this coordination is administered under mandatory procedures set up by the electric power industry's new electricity reliability organization (the North American Electric Reliability Corporation), with oversight provided by the Federal Energy Regulatory Commission and the U.S. Department of Energy.

The National Power Grid

Most of the electrical transmission components have been in existence for many years. It is generally agreed that some replacement and upgrading of current lines will have to be done, and that new lines need to be constructed to maintain the system's overall reliability.

Four significant challenges to improving the power grid infrastructure are:

Siting new transmission lines (and obtaining approval of the new route and needed land) when there is local opposition to constructionDetermining an equitable approach for recovering the construction costs of a transmission line being built within one State when the new line provides economic and system operation benefits to out-of-State customersEnsuring that the network of long-distance transmission lines reaches renewable sites where high-quality renewable resources are located, which are often distant from areas where demand for electricity is concentrated.Addressing the uncertainty in Federal regulatory procedures regarding who is responsible for paying for new transmission lines; this uncertainty affects the private sector's ability to raise money to build them.

There is no "national" power grid. There are actually three power grids operating in the 48 contiguous states: (1) the Eastern Interconnected System (for states east of the Rocky Mountains), (2) the Western Interconnected System (from the Pacific Ocean to the Rocky Mountain states), and (3) the Texas Interconnected System. These systems generally operate independently of each other, although there are limited links between them. Major areas in Canada are totally interconnected with our Western and Eastern power grids, while parts of Mexico have limited connection to the Texas and the Western power grids.

he "Smart Grid" consists of devices connected to transmission and distribution lines that allow utilities and customers to receive digital information from and communicate with the grid. These devices allow a utility to find out where an outage or other problem is on the line and sometimes even fix the problem by sending digital instructions. Smart devices in the home, office, or factory inform consumers of times when an appliance is using relatively high-cost energy and allow consumers to remotely adjust its settings.

Smart devices make a Smart Grid as they help utilities reduce line losses, detect and fix problems faster, and help consumers conserve energy, especially at times when demand reaches significantly high levels or an energy demand reduction is needed to support system reliability.

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HPD cracking down on electric vehicle parking violators

(KHON) It’s one of the biggest complaints the state received from people who drive electric vehicles: others parking in their charging stations when they’re not supposed to.  But police are now cracking down on violators.  Anyone who parks there who’s not supposed to, could receive a citation between $50 and $100.

 

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Repowering South Mississippi Electric Power Association’s J.T. Dudley, Sr. Generation Complex

Repowering two units at the J.T. Dudley, Sr. Generation Complex added 180 MW of high-efficiency capacity to South Mississippi Electric’s portfolio. Now the cooperative can self-produce more than 50% of its electricity needs.

The J.T. Dudley, Sr. Generation Complex, owned and operated by South Mississippi Electric (SME), is located in Jones County, Miss. Originally installed in 1968 at what was then called the Moselle Generating Station were Units 1, 2, and 3, nearly identical 60-MW conventional steam plants. Units 4 and 5, General Electric (GE) 7EA simple cycle combustion turbines, were added in 1997 and 2005, respectively.

Today, the complex consists of five units capable of generating more than 500 MW. The additional capacity will pay long-term dividends to SME’s customers in the form of increased system reliability and more control over its production costs. The cooperative forecasts that as of 2013 it can self-generate 51% of its power needs; it purchases bulk power for the remainder.

The repowering project converted Units 1 and 2 into two, independent 1 x 1 combined cycle units. Both original gas-fired boilers were retired in place and the steam source for each unit was replaced with a new GE 7EA combustion turbine (CT) and a Vogt Power International (VPI) heat recovery steam generator (HRSG). The new power block is located approximately 400 feet from the existing powerhouse, with piping and cable tray routed along a three-level pipe rack between the HRSGs and powerhouse (Figure 1).

Construction began in August 2010. The commercial operation date (COD) for Unit 2 and Unit 1 combustion turbines in simple cycle operation was November and December 2011, respectively. The COD dates for Unit 2 and Unit 1 in combined cycle operation were May and November 2012, respectively.

Burns & McDonnell provided consulting, detailed design, procurement, construction management, and startup services. SME designed, procured, and installed the CT generator step-up transformer and interconnection power line, as well as the existing plant switchyard expansion.

A multi-phase and multi-contract approach was used on the remainder of the project. Beginning in August 2010, James Construction Group kicked off construction with site civil work and foundations, plus electrical and mechanical underground construction. Next, PCL Constructors followed in December 2010 with the combustion turbine and simple cycle portion of the construction project. The Saxon Group handled the final two major construction contracts: electrical and HRSG erection plus the combined cycle balance of plant, beginning work in January 2011 (Figure 2).

2. Refurbish instead of rebuild. The existing three conventional units are shown in the background (outdoor boilers with a
single steam turbine building located behind the boilers) with the two existing 7EA simple cycle combustion turbines (CTs) to
the right of the existing units. The new 7EA CTs are visible in the foreground. Between the new CTs and the three existing
boilers are the two HRSGs being assembled. Each 7EA-HRSG combination supplies steam to a single, existing steam
turbine. The HRSGs are Vogt Power International’s Enhanced Constructability Smart design. The design incorporates pressure parts, pressure part support steel, interconnecting piping, casing, and structural steel into only six shop-fabricated module boxes per HRSG, significantly reducing erection labor expense. The photo was taken during constructionin October 2011.  Courtesy: Burns & McDonnell

The engineering and design of the repowering project was performed with two goals in mind: increased operational flexibility and reuse of existing equipment, where feasible, to minimize project cost. Reused equipment included the steam turbine, boiler feed pumps, condensate pumps, condenser, cooling towers, deaerator, plant air system, and flash evaporator. Details about the major components and equipment used on the repowering project follow.

Combustion Turbines. The two new natural gas–fired GE 7EA CTs are equipped with dry low-NOx technology (DLN1) and each is rated at ~85 MW. Each CT is also equipped with evaporative cooling technology, which increases summer capacity by ~8 MW. At full load, the combustion turbines will provide a flow of 2,225,000 pounds per hour of exhaust gas at 1,022F to each HRSG (Figure 3).

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The “Charge As You Drive” Electric Car

Let’s face it .. electric vehicles have one big serious drawback: cables. You can’t go far in them and when you do you need to grapple with some serpentine cable to get energy back into the car. Green it might be, convenient it certainly ain’t.

Wouldn’t it be great if you could just drive to work and know your car would still be fully charged when you got there? You’d have to do nothing else .. no plugging in, no battery drops, no nothing. You wouldn’t even have to stop at a gas station. Bye bye cable, bye bye pumps : hello freedom!

This isn’t some photovoltaic wet dream of solar efficiency or rehash of energy recovery systems. This is inductive power transfer (IPT) and its being used to turn the next generation of highways into car charging arteries.

The principle behind IPT has been around for ages: it relies on magnetic fields to make electrons to move, thus creating an electric current without a physical connection. It’s how electric toothbrushes and a whole host of other everyday objects get charged up without dangerous open connectors.

The theory of charging electric vehicles this way has also been mooted for years, but no ones managed to make it commercially viable … until now.

HaloIPT is a New Zealand startup whose major investors include the engineering giant Arup. Their solution is simple: two pads, one on the bottom of the car, one under the tarmac, and when the car is over the pad it automatically charges.

Voilà! No cables, no battery drops, no nothing. Simply install the pads on your driveway or office parking spaces, and your electric vehicle can charge whatever the weather in a safe and electrocution-risk-free environment.

But wait a sec, didn’t I mention car charging arteries? Indeed I did, because this is where HaloIPT’s vision starts to take off.

As highways undergo normal maintenance, why not install the pads under the road surface while you’re at it? Many roads already have an electricity infrastructure for street lighting etc; with an upgrade it could easily support the pads (up to 125A is thought to be sufficient).

This way, as the HaloIPT website puts it, “[when] you drive, the pad underneath your electric car picks up charge – safely, reliably – from pads embedded in the road. Every time you pass over a pad, the battery receives a fresh top-up.”

Now you’ve got to admit it, that’s neat!

HaloIPT are currently calling for early adopters to put the system through its paces, although sadly this is limited to the UK and New Zealand only. To take part go to HaloIPT – Projects and click on “Get Involved”.

A full commercial scale demonstration of the technology is planned for 2012.

Picture Credit: Motorway A73 by night by mauricekoop under Creative Commons Attribution No Derivatives License.
Tags: arup, Electric Cars, haloipt, inductive power transfer, ipt, New Zealand

Chris Milton Chris is a seasoned sustainability journalist focusing on business, finance and clean technology. His writing's been carried by a number of highly respected publishers, including The Guardian, The Washington Post and Scientific American. You can follow him on twitter as @britesprite, where he's one of Mashable's top green tweeters and Fast Company's CSR thought leaders. Alternatively you can follow him to the shops... but that would be boring.

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