microgrids

Distributed Generation benefits

Distributed Generation: What Are the Benefits?

Distributed Generation: What Are the Benefits?

Increased efficiency. Reduced rates. Improved reliability. Diminished emissions. If all of that sounds good to you, then you ought to know about the benefits of distributed generation.

A few weeks back, we covered microgrids and why they’re important in the context of the larger, main grid. As you might recall, microgrids are defined not by their size, but rather by their function—crucially, their ability to break off from the main grid and operate autonomously. Got it? Well, if that makes sense, think of distributed generation as a network of systems just like that.

That’s oversimplifying it a little, but the overall concept holds true. Distributed generation is when electricity comes from many small energy sources. Generally, these sources are local and renewable. They’re all connected to the larger grid but can also function separately.

If all this sounds unfamiliar, that’s because it’s not the “normal” way of doing things. But it does have its advantages.

The traditional model

In the traditional transmission and distribution (T&D) grid, large sources provide power to huge numbers of residential, commercial, and industrial customers. Some of those customers live close to the centralized power plants. Other live far away—sometimes very, very far.

In contrast, a distributed generation (DG) system has smaller, decentralized sources that generate electricity much closer to the people who use it. There are lots of producers, and even though they produce less individually, they’re all connected to the grid. Together, they can be quite effective.

Several technologies form the backbone of a DG system. Some of the most prominent are solar, wind, and hydro. Another is cogeneration, which is the production of electricity from what is essentially the leftover energy from other forms of generation. Yet another is an energy storage system, which stays connected to the grid and holds energy until it’s needed.

So what are the benefits of distributed generation? In 2007, the U.S. Department of Energy released a report outlining some of DG’s advantages. Here’s what they came up with (h/t Energy.gov):

  • Increased electric system reliability
  • An emergency supply of power
  • Reduction of peak power requirements
  • Offsets to investments in generation, transmission, or distribution facilities that would otherwise be recovered through rates
  • Provision of ancillary services, including reactive power
  • Improvements in power quality
  • Reductions in land-use effects and rights-of-way acquisition costs
  • Reduction in vulnerability to terrorism and improvements in infrastructure resilience

Those are all really important concepts, but let’s focus on that first one.

Increased reliability, better performance

One way to think about the benefits of distributed energy is to visualize your cell phone’s network. Imagine for a moment that your carrier had only a few towers in just a few spots around the country. The towers would be massive and powerful, but you wouldn’t have the same reliability and coverage that you have now. The reasons should be obvious. With a network of smaller, more evenly placed towers, cell-phone carriers are able to provide the best service possible to their customers.

Distributed generation is no different. When centralized power plants transmit energy over long distances, some of that energy is lost. With distributed generation, the generators are closer to those who use the energy. Thus there’s less waste. Increased efficiency. In the old model, a loss in service at any point of the grid means everyone suffers. In the new model, that’s less likely to happen.

DG can also serve as a backup to the grid, acting as an emergency source for public services in the case of a natural disaster. Here in North Alabama, that kind of service could be invaluable after a tornado. And by producing energy locally, DG systems can reduce demand at peak times in specific areas and alleviate congestion on the main grid.

Finally, because distributed energy tends to come from renewable sources, it’s good for the environment. Using more renewables means lowering emissions. And lowering emissions makes the world a more enjoyable place for all of us.

Microgrids: What are they anyway?

What are Microgrids?

The first thing you need to know about microgrids is that they’re not so micro at all.

Or at least they don’t have to be.

As microgrids have become more widespread in the United States and around the world in recent years, you might have started to think about what they mean to you. But if you’ve ever tried to take a deep dive into the topic, you might have discovered that a single definition of the term is difficult to find.

To wit, there’s this, from CIGRÉ (h/t Microgrids at Berkeley Lab):

Microgrids are electricity distribution systems containing loads and distributed energy resources, (such as distributed generators, storage devices, or controllable loads) that can be operated in a controlled, coordinated way either while connected to the main power network or while islanded.

And this, from the U.S. Dept. of Energy’s Microgrid Exchange Group:

A microgrid is a group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island-mode.

And, much more succinctly, this from Energy.gov: “A microgrid is a local energy grid with control capability, which means it can disconnect from the traditional grid and operate autonomously.”

Renewables such as wind power can be one of the sources for microgrids.

If you’re new to the topic and were reading all of that closely, there’s a decent chance you got bogged down in all the technical talk about distribution systems and interconnected loads. Don’t worry about it—that’s aimed more at specialists.

On the other hand, what you probably understood better were the island metaphors. And that’s critical, because while the term microgrid lead you to believe it’s all about size, the key here is actually autonomy. The Microgrid Institute, which begins its definition by calling a microgrid “a small energy system,” follows that up with this: “Microgrids are defined by their function, not their size.”

So what is that function? Essentially, a microgrid serves as an independent backup to the main grid, or macrogrid, by using the various resources (and they’re sometimes widely varying) at its disposal. That’s all it is. To put it another way, a microgrid generally works within the larger grid, but it can also disconnect and work autonomously as a locally controlled alternative.

Whether it’s because of an emergency, or because of its remote location, a community might need autonomy with its energy supply at certain times. And a microgrid, which is by definition locally controlled, provides that independence.

Microgrids are defined by what they do, not by their size.

Consider, for example, the potential benefits a microgrid can provide for a place like Alabama, which experiences severe weather regularly. In 2011, after a historic round of powerful tornadoes, some parts of the state went without electricity for a week or more. In a situation like that, a microgrid can break off from the main grid and provide an invaluable service to a community. Not only would Alabamians have electricity, but so would emergency-response workers.

“The key to understanding the importance of microgrids was driven home for us here in Alabama after the April 2011 tornadoes” says Daniel Tait, CEO of Energy Alabama. “Modern life is built on energy. Without its uninterrupted supply, especially for long periods of time, things begin to break down. Flexibility and resiliency is the name of the game.”

But that’s not all microgrids can do for a community. According to Berkeley Lab, microgrids can improve efficiency, relieve grid congestion, and provide a more reliable supply of energy, all at reduced cost to consumers. And according to Energy.gov, they can also cut costs, build energy independence and offer more flexibility. Those first two are ideas that everyone can get excited about, and more flexibility means potentially using renewable sources like solar and wind, in addition to whatever powers the macrogrid.

The remote Isle of Eigg derives most of its electricity from a microgrid.

So what does a microgrid-powered community look like? The answer, it turns out, is as varied as all those definitions from before. There’s Mesa Del Sol, a mixed commercial-residential development in New Mexico that harnesses solar power from a photovoltaic system mounted to a parking-lot canopy. Then there’s the Fort Collins Zero Energy District (AKA FortZED) in Colorado, a project aimed at creating as much energy locally as the area uses.

And there’s the remote Isle of Eigg in Scotland’s Inner Hebrides, which demonstrates the concept of islanding in literal fashion. Previously dependent on diesel generators, the 90 residents of the Isle constructed a microgrid that blends various renewables into a community-wide system. Completed in 2008, the microgrid uses hydro, wind, and photovoltaics to produce a reliable electrical supply 24 hours a day.

All of those projects are localized, and the Isle of Eigg is obviously smaller than the others. But the idea here is big, and with all the benefits microgrids can bring to a community, you might see one in your area sooner than you think.

A Pivotal Moment for the Tennessee Valley

A few days ago the Tennessee Valley Authority (TVA) released its draft of their Integrated Resource Plan. This is a study that takes a long-term look at ways that TVA can meet future demand for electricity in new and innovative ways. The IRP helps TVA better serve their customers by envisioning a generation mix that can respond to changing market conditions while meeting consumer demand for cleaner energy.

On April 9th from 7:00 PM – 8:30 PM, TVA will host a public meeting at the Huntsville/Madison County Chamber of Commerce to receive feedback and discuss this draft. This is your chance to speak out for clean energy! 

In this draft, TVA is making a demonstrable effort to increase investment in clean energy like energy efficiency and solar. We are asking for your help to show TVA that we support their steps AND would encourage even more investment in clean energy like wind, distributed storage and microgrids. 

To get more information or read the full draft you can visit: https://www.tva.gov/file_source/TVA/Site%20Content/Environment/Environmental%20Stewardship/IRP/Documents/2015_irp.pdf