More Companies Focus on Utility-scale Renewable Energy Integration

The energy peaks and valleys that can be caused by the inclusion of large amounts of wind- and solar-generated energy on the grid can be problematic for utilities trying to manage large energy loads.

"Storage is, to us at Clean Edge, one of the big challenges in order to get to a large scale-up of utility-scale wind power and solar power," said Clint Wilder, a RenewableEnergyWorld.com contributing writer and contributing editor at Clean Edge.

"We're seeing a lot of attention focused in this area," Wilder continued. "We see utilities doing test projects, venture capitalist investments in this space, and it shows that wind and solar have grown up a lot."

Wilder feels that interest in storage is being driven by utilities, because, as he says, when you talk about electricity, utilities are the experts.

"Smart grid, storage and grid infrastructure are all related and are all about how we update and improve our electricity delivery system to bring it up to 21st century standards...this is a major part of this..new energy infrastructure, new energy economy that everyone's talking about," he said.

One utility that is working feverishly to overcome its grid stabilization problems is ESB International, a wholly-owned subsidiary of the Electricity Supply Board (ESB), which is Ireland's national power utility. Phillip LeGoy, senior consultant power plant design, detailed the challenges that the utility has been faced with in a session at the conference about energy storage.

Ireland, an island the size of South Carolina, is blessed with a large wind resource and has "just been going nuts putting up wind farms" said LeGoy. In fact, there are times when the country is getting a full 25% of its electricity from wind. "It's a real success story," he added.

But the problems come about when the wind stops blowing, he explained. "If I've got 1000 MW of wind power, it is a detrimental thing when it goes offline," he said.

The country is exploring creating more interconnection between Ireland and the UK but finding that option too expensive for now. What might be a feasible option, however, and one that LeGoy is working on is energy storage.

Of 6 energy storage possibilities the company is exploring, LeGoy is personally involved with one that involves hydrogen fuel cells.

If his plan works the utility would use electrolysis to produce hydrogen from electricity from the wind, wave and tidal power resources that are currently in place or being explored.

"We'll use fuel cells to reconvert the hydrogen back into electricity and we'll use energy recovery methods to improve the efficiencies to what they say is 49%...and that's a full thermal cycle efficiency," he said. Ideally, they'll to end up with 20 MW of continuous storage for 24 hours.

Interestingly, the country would also be able to sell the hydrogen and oxygen it will be creating. LeGoy envisions each of the 25-MW wind farms that are now scattered around Ireland or just off its coast generating hydrogen. Then, a barge would travel around to each site and pick up the hydrogen, delivering it to, possibly, automotive fueling stations that may eventually be set up across the country.

The hydrogen storage tanks are off-the shelf, he said, as are the automotive fueling stations.

Despite what might seem to be a complicated problem with a complicated solution, the utility is still very positive about wind energy and LeGoy indicated that there are, in fact, new plans to develop even more wind farms throughout the country.

"We believe renewable energy can be stored and stored renewable energy can help stabilize our system" he said.

For more on Ireland's wind power challenges, click here to read Phillip LeGoy's paper entitled "Large Scale Hydrogen Fuel Cells - A Facilitating Solution for Renewable Energy."

Keeping the grid stable is also a concern of inverter maker, Satcon. But Dr. Leo Casey, vice president and chief technology officer isn't a huge believer in energy storage.

"The idea of time-shifting energy, for that really to be successful we're going to have to see time-of day rates," he said.

Casey also said that what utilities need to be concerned about are ramp rates. In other words a large, utility-scale renewable energy plant can't come online or offline quickly or it will shock the system, which is exactly what is happening in Ireland.

The key, then, according to Casey is balancing the load; giving the utility the ability to bring on or off a generation source. He pointed out that utilities are running Danish wind farms at 30% below their capability so that they can safely ramp down.

For PV, he said, it's a little easier to forecast. For example, a large cloud formation can be seen from a distance and planned for. Casey thinks that utilities will need a small amount of energy storage to safely ramp down but it's really just a small amount.

"So there is the idea of ramp rates, you want to slow down the rate of change of the PV farm. It does not take that much energy to do that and it's not that expensive," Casey said.

The point is that utilities need to be in the driver seat when it comes to adding renewable energy into their energy mix. Satcon's newest inverter the Solstice was designed to help utilities control how the energy from large PV farms is fed into the grid.

Southern California Edison is working on a large distributed PV farm that will eventually be 250 MW of PV residing on 200 rooftops but controlled as if it were one generating source. "They are looking for exactly those advanced features that we've been working on in our Solstice program of reactive power control, harmonic cancellation, remote control of real power and we think that's the future, utility control," Casey said.

Lastly, another company interested in giving utilities more control over their electrical load is Ice Energy, a company that offers a less energy-intensive commercial-scale air conditioner. The unit, which would be purchased by utilities and installed on businesses, makes ice at night when the electric load is low and then deploys it in the form of air conditioning during the day.

The company says that air conditioning is one of the greatest drains on utility's load pulling as much as 7-8000 watts but its Ice Bear pulls only about 300 watts.

Ice Energy is an enabling resource for renewables like wind and solar, according to Randy Zwetzig the company's vice president. "Ideally we'd like to store that wind energy that is being generated at night and deliver it during the day," he said.

Zwetzig explained that whereas PV panels peak around noon and then drop to about 50% capacity around 5:00 in the afternoon but a utility's load peaks around 4:30 or 5:00 in the afternoon, when PV drops off, it creates a bigger spike for the grid.

"So what we can do is take a large part of a building's load off, say about 50% of the building's electrical load by shifting that air conditioner's use or eliminating that peak demand that occurs at about 5:00 in the afternoon therefore providing a much flatter delivery curve for the solar PV system," he said.

The fact is that the utility is now front and center when it comes to renewable energy. With keeping the grid stable while incorporating renewables into their portfolios as their main concern solutions like energy storage, the smart grid and grid infrastructure will continue to play key roles.

To see our video interviews with Satcon, Ice Energy and Clint Wilder, play the video below.