Geothermal power is generally a great source of renewable energy because it’s reliable and can be relatively affordable in areas with good resources. The Big Island of Hawaii already gets up to 38 megawatts of geothermal power from a plant in the district of Puna, the southeast part of the island.

Hawaii Electric Light Co. (HELCO), the private utility that serves the Big Island of Hawaii, announced recently that it will be adding 25 megawatts of geothermal power in the Puna region to its power generation mix. I’ll examine the pros and cons of this move in this article.

I live, part-time, not too far from the existing geothermal plant, and I know many of the other residents who live nearby too. There is unfortunately a long and negative history with respect to this plant, which at first blush one would think would be enthusiastically welcomed as a clean and green source of power and jobs. The basic problem is that the plant periodically outgases some pretty noxious chemicals into the local environment, and has done so for decades.

There are also real concerns on the part of some locals about the traditional spiritual prohibitions (kapu) related to messing with the volcano system and Pele, the volcano goddess of Hawaiian mythology. I won’t dwell on these concerns here, but they are real concerns for many on the Big Island.

Ormat Technologies, a company with headquarters in Israel but with a U.S. subsidiary based in Reno, Nevada, operates the existing 38 megawatts of geothermal, known as Puna Geothermal Venture (PGV). This plant has provided reliable power to the island since it opened in 1993. Ormat acquired it in 2004.

Jay Ignacio, HELCO’s president, stated the following in the announcement for the new 25 megawatts: “We have continued to pursue ways to increase our use of renewable energy and lower costs to our customers, while also ensuring reliable service. Ormat was selected based on numerous criteria, including attractive pricing, technical design and capability, financial soundness, as well as commitment to resolving all environmental issues and to working with our Hawaii Island communities.”

I’ve heard and read about various blowouts from the plant in my numerous trips to the island in the last couple of years. The most dangerous gas release occurred in 1991, as PGV was being constructed, and a major report was completed in 1992 to determine how this happened. Many gas releases have occurred since, including a large one induced by the remnants of Hurricane Iselle that hit the island on August 7, 2014. Ormat was fined $24,000 for that release in a ruling from January of this year.

Hazen Komraus, a local home builder and long-time resident of the Puna area, had this to say about HELCO’s plans: “Ormat has shown an utter and consistent inability to accomplish anything close to the promise of geothermal power done well. Thirty years of evacuations, disdain toward the community, lies, and incompetence has led to the lack of any support from the community for the company. They've blown their social capital."

Surprisingly, it's only very recently that a significant study was initiated to investigate the health effects of PGV. This study started this year and may take three years to complete. The gases that PGV emits are natural in that they come from the natural processes that lead to the lava flows and volcanoes that are one of the more remarkable features of living on the Big Island. However, these releases wouldn’t happen where and when they have if PGV wasn’t operating.

PGV is located very close to the homes of several thousand residents (mostly Leilani Estates, a large subdivision a few miles from Pahoa). In contrast, the natural outgasing from Kilauea and Pu’u O’o  (the second vent of the Kilauea volcanic system) are miles downwind and rarely affect these communities.

Since PGV is the only geothermal plant currently operating on the Big Island, it also raises difficult questions about reliability and security, particularly if it’s expanded. What if an earthquake knocked the plant offline temporarily or permanently? If PGV is expanded from its current 38 megawatts, as HELCO is planning, this potential vulnerability will be exacerbated. A single volcanic or earthquake event could take all of the plants offline and, at 63 megawatts, this would be a very significant deficit for the Big Island grid, which includes currently 182 megawatts of generation. So if the expanded PGV goes offline for whatever reason, the island grid will lose about one-third of its power in an instant. This seems like an unwise move.

Furthermore, the fact that an active lava flow has been threatening Puna for almost a year now isn’t encouraging for the future of PGV. While the current lava flow (known as the June 27 flow, for the date that it began) is no longer headed for the town of Pahoa, the heart of the Puna region, it highlights the very real possibility of major destruction being caused by the active volcanoes in the area, as with the destruction of the nearby towns of Kapoho in 1960 and Kalapana in 1986. Lava and volcanoes are real threats on the Big Island, and PGV is located literally in the heart of the very rift zone that is considered to be the most hazardous volcanic area on the island (Lava Risk Zone 1).

FIGURE 1: U.S. Geological Survey Map Showing the East Rift Zone in Relation to PGV

It seems, then, that geothermal isn’t a very good idea for the highly volatile Puna region. HELCO’s 2014 Power Supply Improvement Plan, a major document that shows how HELCO can get to 92 percent renewables by 2030, calls for 25 megawatts of new geothermal to be added on the Kona side of the island, which would reduce lava risk substantially, and probably reduce earthquake risks too. Apparently, a plant on the Kona side can’t be built cost-effectively, judging by the fact that none of the 2014 geothermal bids submitted for projects on the Kona side were selected by HELCO.

Until recently, HELCO was scrambling to ensure that power supplies for the Puna region will remain operational if the June 27 flow takes out any power lines. The flow has been on again and off again, for many months now. See Figure 2 for the most recent map of the June 27 flow, showing a number of fingers less than half a mile from the town and the highway into Pahoa from Hilo.

FIGURE 2: June 27 Lava Flow

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Source: Hawaii Volcanoes Observatory

If the flow does cross the highway, many thousands of people who live in lower Puna could be left without power, at least temporarily. It may also cut off PGV from the rest of the grid. The risks I’m talking about here are not abstract.

What should HELCO do to reach the 2030 renewable energy goals?

A major benefit of other types of renewables, namely wind and solar, is that these technologies not only are already cost-effective, but that they can also be distributed widely around the island. Lava flows can, of course, take out wind turbines and solar panels as well as geothermal plants, but the modular nature of solar and wind means that only the components actually destroyed are taken out, and the rest of the project components can stay on-line if the power lines are kept intact. And if these technologies are widely distributed around the island, as is already the case for solar, and to a lesser degree for wind, the risk of any major disruption from earthquakes or lava is strongly mitigated.

At the least, HELCO should be required to wait for the current air pollution study -- currently scheduled for 2018 -- to be completed before commencing any expansion of PGV.

In sum, the current lava flow is serious but will eventually stop and the community will recover, as will HELCO’s grid. It’s a cautionary tale, but it is far from being a major roadblock to getting the Big Island off fossil fuels. Instead, it could be seen as a major boost for these efforts, because it highlights the benefits of distributed renewables. It seems that a combination of wind, solar, biomass, energystorageand some residual diesel or liquefied natural gas power plants can and should supply 100 percent of the power on the Big Island. And it is entirely possible that Ormat could institute major improvements to the current PGV operations in such a way that local opposition to this plant could be reduced significantly.

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Tam Hunt is author of the upcoming book, The Solar Singularity: Why Our Energy Future Is So Bright. Hunt is a lawyer and owner of Community Renewable Solutions LLC, a renewable energy consulting and law firm that focuses on policy advocacy and solar and energy storage project development.