The new all-of-the above: HECO looks to wind, solar and beyond for 100% renewables mandate

Hawaiian Electric Co.'s roadmap to a 100% renewables grid will rely on EVs and DERs alongside established central-station renewables

Colton Ching missed seeing Tom Brady's incredible Superbowl comeback in February, but not becauseas so many fanshe had given up on the game.

Ching, who is senior vice president of planning and technology at Hawaiian Electric Co., lost power during the second quarter and didn't witness the Patriots march back from a 25-point deficit late in the game. A storm that socked the windward side of Oahu downed trees and caused widespread blackouts, frustrating football fans and highlighting the unique challenges faced by HECO.

The largest power provider in Hawaii must ultimately deliver 100% renewable power across a geographically diverse set of islands. It's a high bar for any utility in the country, but while Hawaii has plenty of wind and solar potential, it still wont be enough in some areas. On Oahu, where about two-thirds of the state's population resides, Ching said covering every rooftop with solar panels wouldn't even work.

In fact, wind and solar and battery storage combined still wouldn't reliably get the job done, he said. That means HECO is turning to a wide range of resources and deploying them in ways that, because of the state's unique geography, look different than what utilities on the mainland might execute.

"One of the things that makes the Hawaii grid different from the mainland is the reliance on distributed, connected resources. Whether they be solar PV or electric vehicles or dedicated storage, they are going to be relied on more heavily to actually operate the grid," said Ching. "Not just at the distribution level, but the entire system."

Demand management

Demand response and other demand side management programs have traditionally been used to shift bulk load to cheaper or less congested times of the day. The programs typically go after large customers first, simply because it is the easiest to dispatch and monitor and provides a large chunk of demand. But in Hawaii, for several reasons, these programs are altered.

"Demand response and demand side management will be different in a couple of ways," said Ching. "Traditional DR was all about reducing your peak for the day. For Hawaii, we see a role for demand response to do that, but also to provide a role to help us manage the grid at all hours of the day."

If a forecast predicts little solar energy will be generated on a particular day, but wind is expected to be strong, the utility works to move demand over to evening hours. On the other hand, when the sun is shining bright HECO tries to move electric vehicle charging over to those hours.

"It's a very different role for demand response," said Ching. Also, HECO doesn't have large industrial customers. The utility's largest loads are the University of Hawaii and military bases, which typically have demand closer to homes and small offices.

"Demand response will require us to connect to many many different customers, loads that are discretionary and flexible, rather than traditional demand response which targets a few large customers," Ching said. "The design of the program itself will have to change."

HECO is working to develop a  Power Supply Improvement Plan (PSIP), outlining a plan to reach 100% renewable energy. The state's Public Utilities Commission earlier this year rejected the utility's plan, arguing it was too costly, needed to do more to integrate renewable energy, and did not sufficiently focus on distributed resources. The utility has until the end of June to revise its plan. "We understand where the PUC order is directing us," said Ching. "We are planning a considerable amount of demand response."

The utility believes that in the next three decades, more than 70% of the generation to run the grid during the day will come from devices interconnected at the distribution level.

"When you think of the grid of the future ... now our distribution system is the key connector of the system's generation," said Ching. "When you think about bulk transmission on the mainland being key to connecting generators and providing bulk shifting of load, in Hawaii our distribution system will serve that role. It will no longer be the transmission system."

The transmission system will still have generation connected to it, but "especially in the daytime, it will be the minority," he said. "As we think about what kind of automation, visibility and control we'll need ... our distribution system is our next transmission system."

Renewables and storage

HECO wants to reach almost 50% renewable power by 2020, aiming to go all in by 2040. The utility's PSIP says that would put it five years ahead of the state's mandated goal. The plan, now being reworked, called for 48% renewable power by 2020 without the use of imported liquefied natural gas.

The proposal envisioned the addition of 360 MW of grid-scale solar, 157 MW of wind energy and 115 MW from demand response programs by 2050.

But again, Hawaii's geography and population mean the goals are easier in some areas than others. On the island of Hawaii, HECO is already at 50%, said Ching. But there are less than 200,000 people living there, compared with about 1 million on Oahu, where the capital of Honolulu is located.

"Here in Oahu, the first challenge is finding enough renewable energy," said Ching. "The second is, can we get it cost-effectively. ... You would have to overbuild your wind, solar and storage to such an extent that keeping a certain amount of conventional generation will be necessary."

That "conventional" power is biofuel and thermal generation, he said.

​Going from 50% renewables to 100% is "going to require a different order of lift," said Ching. "You try to get all the low hanging fruit in your first percentages, but what we see as a challenge is getting enough cost-effective  renewables on Oahu. Big Island and Maui, where population is relatively low, that's arelatively speakingthat's a pretty easy challenge to take on."

Ching said given the large amount of variable generation HECO gets from solar and wind, storage will need to play a robust part on the utility grid. But as opposed to just supplying energy, the utility needs stabilization services most of all.

"Our ramping events are getting bigger and bigger, and are ramping faster and faster as we add more solar and wind," said Ching. 

The most urgent need is for fast frequency regulation and contingency reserve. HECO's grid is so small that a large fluctuations in load and demand can cause frequencies to "change almost instantaneously," said Ching, and can "change to such a large degree that the variation can cause other generators to go offline."

"It's a vicious cycle, so we see a role for batteries to provide a lot of power in just milliseconds to stabilize the grid," he said.​

Electric vehicles: an integrated approach to fossil fuel use

Electric vehicles play a major role in HECO's plans, in part because the state's efforts to reduce emissions covers all sectors. Bringing more plug-in vehicles online helps reduce gasoline consumption and greenhouse gas emissions, along with providing a grid resource, and Hawaii has been working to incentivize the new cars.

Earlier this year, both HECO and Kauaʻi Island Utility Cooperative offered deep discounts on a new Nissan Leaf, to the tune of about $10,000 off the usual price. And a report last year found January 2016 vehicle registrations for plug-in vehicles totaled more than 4,000, and showed a 26% increase over the previous year.

"We see a very advantageous opportunity with things like EVs, were we can find strategies and ways to allow customers to do the bulk of their charging in the daytime, when we need the load to absorb as much renewable energy as we can, rather than using a battery," said Ching.

So far there are no plans to use EVs as a two-way capable resources to provide grid services. Those tasks will be left up to dedicated batteries, Ching said. "EVs can do a pretty good job of things like bulk shifting."

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Filed Under: Transmission & Distribution Solar & Renewables Energy Storage Distributed Energy Efficiency & Demand Response
Top image credit: Flickr; Roxanne Ready