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Process Storage: The Missing Link in the Utility Energy Portfolio

Sets of cooling towers in conditioning systems

Sets of cooling towers in conditioning systems

Some people hear the word “storage,” and all they think of is batteries. Most utility people aren’t that short sighted. They’ll remember mechanical forms of storage, like flywheels or the water trapped behind a dam. But – and I admit I’m a little partial here – I think the most efficient storage is process storage, or the storage inherent in the flexibility of controlled loads.

Given the choice between using peaking generators, battery storage or a process storage mechanism like the Enbala network, you can’t beat process storage for delivering great energy efficiency. A peaker plant located 300 miles away from the problem will experience line loss on top of the thermodynamic inefficiency of the plant itself, which can hover below 50 percent.

And, on the cost basis, process storage is far more affordable than grid-scale battery storage, and has different characteristics. The round-trip efficiency of the process storage is actually quite high. With batteries, you’re taking a device, taking energy off the grid to charge up that device, going through the necessary AC/DC conversions, then releasing that energy back into the grid at which point, again, you have energy conversions occurring.

The Case for Leveraging Process Storage

Process storage has high round-trip efficiency because there are no conversions involved. You’re just letting the system do work it was going to do anyway, whether it was chilling a building down, heating up a tank of water, pumping water from point A to point B, or supporting the grid because the grid operator called a device into action. Energy storage devices like batteries, they may be great as shock absorbers for the grid, but don’t forget about round trip efficiency.

What does process storage look like from an energy profile standpoint? A battery has a very good power profile. It can respond to a power signal or a disturbance from a power systems perspective very, very quickly. But in terms of its energy storage, well, that’s still quite low at this point. Even the bigger devices have only around five-hour longevity. With process storage, there are some resources that can be very fast, although they generally won’t be as fast as a battery. However, the energy capability is much longer than battery storage, so the power signatures are different.

Brave New Approaches for a Brave New World

I believe that in this world, this new grid world, the grid-edge world, it’s going to be a combination of multiple approaches that will fix a lot of the decentralized grid problems we now have. I’m not against batteries; I just think process storage devices should be considered in that same category, because at bottom, it is a virtual storage resource when controlled by a network that can leverages its capabilities.

Add in smart solar inverters, and then you have a network can support system voltage quickly, too. At that point, you have a system for regulation service, flexibility, contingency, energy and capacity. It’s a comprehensive approach that can benefit utilities, grid operators and their customers alike.

The Grid of the Future – a Bird’s-eye View

A “mumuration” of starling is a remarkable thing. Huge numbers of birds — thousands and hundreds of thousands — fly together in unison and don’t collide. Scientists have found that each bird monitors the state of adjacent birds and responds to minute changes in direction from its neighbors. There is no control from any leadership, and yet the flock operates smoothly. This approach enables a large number of birds to fly successfully as a flock.

A power system with a high penetration of distributed resources will need a similar autonomous yet distributed control system that can allow local measurements to be used to provide immediate local control. This will augment central management and coordination in order to maintain overall power system control.

Ultimately, we believe we’ll need to take local measurements, e.g. at the neighborhood Walmart store, using phasor measurement units (PMU). Also called synchrophasors, these devices will capture phase angle and magnitude of the voltage signal at each location on a distribution feeder, which will give utilities real information on the state of the feeder, unlike the measurement of watts and VARs measured at a load drop, which provides information on the load itself.

Any change in generation or load at any device will impact phasor values of all devices on the line. Each node in the network will sense a change and will attempt to return the node to its pre-determined target. So, a change in generation at a solar site may be automatically offset by adjusting the power consumption in a load capacity system at one or more nearby sites, while a voltage change may be corrected by the management of one or more solar smart inverters.

Put another way, when clouds pass over the solar array atop the Walmart, the device at the Home Depot will know, and it will shed load according to customer constraints at the do-it-yourselfer’s store. Or, when voltage needs correction, the smart inverters at the Walmart could kick in to do the job.

What everybody is doing now with demand management is collecting data, doing calculations somewhere up above and sending signals back down to devices with instructions. But, you need to be fast about this. You need to take measurements locally and act based on those measurements. You have to have enough intelligence and control at grid edge so that devices know what to do.

That’s what the Enbala platform is capable of doing. It’s our vision for the grid of the future.

The Interconnected World: How Engaged are Electricity Customers with Their Utility?

custengIn today’s fast-paced digital world, we are all constantly connected. Even the smart phone you carry has immeasurable reach, whether it is to specific people, to your work or home email, to your bank account, or even to tell you how late your public transportation is going to be. The modern-day customer wants access to information and extensive communication in all aspects of their lives. This is no different when we look at a utility’s customer base. Although electric utilities provide essential services to their customers, a two-way, continuously connected relationship is becoming more important to manage a reliable and efficient power system, benefiting both the utility and satisfying their customers’ needs.

Generally, customers are accustomed to a one-way relationship with their utility – they consume whatever power they need, when they need it, and they receive a bill at the end of the billing period. This is the traditional way customers think about their utilities (if they do at all). But today, there is significant value for both the customer and the utility in establishing a two-way information exchange.

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Energy Efficiency: How can it be Achieved at all Levels of the Power System?

power-plantA recent Enbala blog entry discusses energy efficiency, providing background and context on how it is traditionally viewed and how industry perspective on energy efficiency needs to be expanded. A more holistic approach to grid operation that utilizes state-of-the-art smart grid technologies would allow for further efficiency improvements to the overall power system – not just at the end user. Let’s look at more details on how intelligently managing the power usage of large electricity users can improve both generation and delivery efficiencies.

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Hydro Storage: An Efficient and Lucrative Way to Store Energy

hydroelectricEnergy storage is a hot topic in today’s electricity industry – thanks to the increasing amount of clean, renewable energy connecting to the grid to support our environment. Because of the variable and intermittent nature of renewable energy (wind solar), energy storage has become a sort of “holy grail” – grid operators are looking for ways to store the energy produced by these sources during the off peak. New and innovative storage technologies are coming to market in large numbers, but there is a type of cost-effective storage that certain utilities are already using, taking advantage of naturally occurring gravity and water.

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Consider a New Perspective on Energy Efficiency

Energy consumption is on the rise – it has been for several decades, and forecasts predict that this will continue into the foreseeable future. It will become an issue as this proceeds in the years to come.

energy-consumption-graphNew technologies continue to be developed and used to make our lives so much more productive, entertaining and fulfilling. Yet we live on a finite planet with finite resources. These technologies require energy, and that energy has to come from somewhere. Emerging markets like China and India will continue to grow and surpass North America and Western Europe in energy consumption. This will increase prices as well as greenhouse gas emissions at a time when we need to make drastic emissions cuts to be confident in a comfortable future for our planet.

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The Evolving Electricity Grid: What are the challenges facing today’s power system and how can we solve them?

Today’s electrical power grid is over 100 years old, has been carefully designed and engineered and a number of operational standards have been developed to ensure a reliable electricity supply.

The Concepts Behind Traditional Power System Design

The system design was based on a few simple ideas:

  • Electricity generation is centralized in relatively few locations, generated by large power plants that can be easily controlled as needed
  • Utilities and electricity system operators continuously work to meet demand for electricity; and this demand is relatively outspread, occurs at random locations and varying magnitudes and traditionally, not easily controlled
  • The power system is like a gravity-driven water system, where the power flows “downhill” to electricity users; it is designed to deliver high-quality electricity to every user under all but extreme conditions and this delivery is controlled, for the most part, at the generating station
  • Energy generally flows in one direction in the distribution network – from the sources of supply to the electricity customers

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