Smart Grid, green power and renewable energy have changed the way the electric power industry does business. Today's utilities have smart meters, intelligent substations and digital capabilities coupled with wind turbines, solar plants and biomass. The quest for improved reliability, together with cleaning up the environment using friendly alternative energy sources, has become a global concern.

What is next in the evolution the industry is experiencing? Is there something missing from the balance? Where does the industry go from here? Are all the parts in place now? Can utilities begin to relax and concentrate on the business of business? Regrettably, there is one critical technology lagging behind.

The Missing Link

Storage is missing. The electric power industry needs storage for the successful integration of renewable energy into the grid, to increase the efficiency of existing power plants and transmission facilities, and to provide better power quality. Without energy storage, the industry is locked into following the outdated policies of the 20th century. The policies consist of building and supporting a power network designed to meet the highest peak load on the hottest day of the year. Utilities do this even when it means more than 50% of the system sits idle most of the year.

Electricity is unlike oil, coal, natural gas or nuclear energy; it has no storage capacity built into it. How many times have industry folk described a transmission line like a water pipe or a transformer like a pressure-reducing valve to a layperson? Unfortunately, electric transmission and distribution systems do not have storage tanks. They are energized only as long as the generator keeps pumping watts into the system.

A utility can stockpile a month's worth of coal or oil at the power plant. Coal and oil have tangible properties, but electricity is another matter. Electricity can only be stored directly by capacitors and coils, which are being incorporated into several new technologies. In practice, however, electricity must be stored indirectly by converting it into some form of mechanical, chemical or kinetic energy and then reconverted into electricity.

Only A Small Percentage

A few years ago, the Electric Power Research Institute (Palo Alto, California) and the Department of Energy (DOE) collaborated on the Handbook of Energy Storage for Transmission and Distribution Applications. The handbook had some interesting statistics about energy storage on a national level. The U.S. cycles about 2.5% of its electricity through energy-storage facilities, which are mostly pumped-hydro sites. Europe cycles roughly 10%, and Japan cycles about 15% of their electricity through energy-storage facilities.

Wind- and solar-generated electricity are inherently intermittent, which can be a problem as large blocks of these types of generation are connected to the grid. Thermal and hydro generation are designed to operate continuously, delivering power to the load. This is called dispatchable power, meaning the generator can be turned off and on as needed. Conversely, wind and solar generation are dependent on weather conditions.

Thermal and hydro generation provide firm power, which means the power does not vary. The voltage and power levels are set by the ratings of the generating and transmission equipment used to supply electricity to the end user. The output of wind and solar generation varies with the force of the wind or the intensity of the sun.

Dispatchable Versus Non-Dispatchable

According to the latest data available from the DOE, generation increased by 2.3% in 2007. This increase represents 8673 MW. Almost 60% (5186 MW) of this new capacity is non-dispatchable wind generation. Renewable energy sources may be part of the solution to improve the environment, but they come at a cost. They are sporadic and erratic.

The sun only shines about 10 to 12 hours a day; solar power is strongest from 10 a.m. to 2 p.m. each day and decreases with cloud coverage. Wind sometimes does not blow and the wind farm sits idle, which is why wind is referred to as non-dispatchable. As these technologies represent larger penetrations into the grid's generation capacities, these attributes will have to be improved.

Also needing improvement is the public's perception of renewable energy. It has to change so everyone understands that without energy storage, renewable power cannot replace coal, natural gas and nuclear generation on a megawatt-for-megawatt basis. As an industry, nothing has been done to change the public's opinion.

Who can forget what happened in Texas in 2008?

When The Wind Stops

Reuters reported that in February 2008 the Electric Reliability Council of Texas (ERCOT; Austin, Texas) declared a stage-one emergency when a sudden drop in wind generation took place. The wind stopped blowing and wind generation went from more than 1700 MW to approximately 300 MW in about 10 minutes. At the same time, ERCOT's demand was increasing from about 31,000 MW to a peak of roughly 35,600 MW (Murphy's law in action).

ERCOT had to curtail power (1100 MW) to interruptible customers. The emergency lasted three hours before reserves were back to normal. The press had a field day with this one, but there was no mention of using energy storage to prevent future events.

Worldwide wind capacities are increasing, and the percentage of wind generation is gaining on conventional generation.

• The American Wind Energy Association reported that the installed wind-generation capacity in the U.S. as of March 2009 was 28,206 MW.

• The European Wind Energy Association reported that by the end of 2008, there was 65,933 MW of wind generation in Europe.

• The Global Wind Energy Council (GWEC) reported that by the end of 2008, China had installed more than 12,200 MW and has plans to triple that number in the next few years.

• Globally, GWEC reported that the total wind-generation capacity at the end of 2008 was more than 120 GW.

These are impressive figures, and they are certainly going to help meet the demands of a society hungry for clean electricity, but the public does not understand the difference between the potential generation and the actual generation of the wind farm.

The headlines proclaiming more than 120 GW of wind generation installed in the world refer to the power the turbines are able to generate, not the gigawatts actually delivered. Think about the speedometer in a car. It registers up to 120 mph. If the average driving speed is 60 mph, the capacity factor is 50%. Studies place the average wind farm's capacity factor at about 35% without energy storage. In other words, a 100-MW wind farm would have to be derated to 35 MW. A nuclear plant's capacity factor is roughly 90% and a thermal plant is about 70% to 80%.

Energy-Storage Needs

The DOE's Office of Energy Efficiency and Renewable Energy published a report in 2008 titled “20% Wind Energy by 2030: Increasing Wind Energy's Contribution to U.S. Electricity Supply.” The 248-page report supports the installation of wind generation in the amount of 20% of capacity of the grid by 2030. Interestingly, the entire DOE report contains only two references to energy storage.

One reference stated that energy storage is a valuable resource. The other suggested that “energy storage in the form of pumped hydro or compressed air should be dedicated to supply backup or firming and shaping services to wind plants.” The report concluded that energy storage would not be necessary in an ideally integrated grid, but it did not define whether the current grid was ideally integrated. Since the keyword here is ideally, it is highly doubtful such a thing exists in the real world. This implies energy storage is needed if the industry is to add large blocks of wind generation.

The DOE's Office of Vehicle Technologies published its “Progress Report for Energy Storage Research and Development” in January 2009. This report concluded that energy storage offers “the possibilities of reducing our dependence on foreign oil and potential negative impacts of increasing prices for that oil.”

Many new technologies are coming from the research laboratories and finding niche applications. These technologies are then moving into pilot programs throughout the power industry.

Salting Away Electricity

Electrical energy storage can be thought of as stockpiling low-cost electricity generated during off-peak hours, much like the coal pile mentioned previously. This improves the efficient use of the existing generation assets. Energy storage can be used to replace the need for additional peaking power plants by feeding this stockpile back to the grid. Another benefit is the need to use generation for load following or spinning reserve, which can be supplied from the amassed electricity. It also saves fossil fuels and reduces air pollution.

So, what are the catalysts to accelerate the integration of underused storage technologies? Alex Rojas, director of asset condition at Quanta Technology (Raleigh, North Carolina), offered his perspective: “Core technology developers will play a key role in packaging subcomponents in the most cost-effective manner, while maintaining power efficiency, reliability, high cyclic life as well as calendar life. Further, based on these performance parameters, they must help the industry develop financial models that would justify the implementation of their individual technologies for specific applications.”

No Silver Bullet

Like the intelligent grid, energy storage certainly is not the silver bullet destined to correct all the woes of the industry, but there are significant benefits energy storage brings to the grid. There are choices for the each segment of the industry, including bulk transmission, distribution and the end user. Stored energy can provide electric power lasting for a few cycles to hours. It can supply this power from a few watts to megawatts.

“Technology developers need the support of all other industry players,” said Rojas. “Transmission and distribution system operators must start or continue updating their use of traditional technologies and market regulations to embrace these new system components. Facility developers must train their engineering staff in the design, erection and commissioning of power plants with non-traditional components. Investors must think outside the box and examine the risk and reward probabilities of investing in core technology development, as well as in the building and operation of such facilities. Government must implement policies similar to those in place to foment the development and integration of renewable energy technologies.”

Globally, the electric power industry is more aware of the environment and the need for efficient use of resources. Electricity generated from renewable energy sources such as wind and solar has enormous potential for meeting the electricity demands and protecting the environment.

Electricity is the only commodity simultaneously produced and consumed. As such, it requires a very sophisticated real-time, just-in-time balancing act of supply and demand that is dependent on variable end-user demands and the continually changing weather system. Today's electrical grid operates effectively without storage, but it is severely challenged. The grid would be more efficient and reliable if it incorporated cost-effective ways of storing electrical energy.

Storing Off-Peak Electricity in the Form of Hydrogen

The present processes to convert water to oxygen and hydrogen require expensive catalysts or extreme heat and pressure. The holy grail of energy conversion has been the promise of a clean and simple process to capture hydrogen and oxygen directly for use in cars equipped with fuel cells. With a more efficient process, the industry could bypass today's required step of cleaning up natural gas for use in fuel cells (impurities tend to trash the fuel cell membranes).

What if we could use electricity from wind and solar to convert water to oxygen and hydrogen? In the April 2009 issue of U.S. News & World Report, “6 Scientists on the Cutting Edge of Energy and Environmental Research” described how Massachusetts Institute of Technology researcher Daniel Noceri and his team of researchers have developed a new catalyst consisting of cobalt metal, phosphate and an electrode. When the catalyst is placed in water and electricity runs through the electrode, oxygen gas is produced. With another catalyst is applied, hydrogen gas is produced.

The focus of Noceri's effort and a part of the MIT Solar Revolution Project (SRP) is to transform solar-powered electricity from a “boutique” option to an affordable, dependable, mainstream energy solution through energy storage using hydrogen.

The SRP, funded by a $10 million gift from the Chesonis Foundation, explores new materials and systems that could dramatically accelerate the availability of solar energy. The goal of SRP is to move this time frame nearer to the present, with a 10-year commitment to establish a new base of scientific knowledge.