Solar Microgrids May Not Fix the Caribbean’s Devastated Power Systems

After the destruction inflicted across the Caribbean by hurricanes Harvey, Irma, and Maria, renewable energy advocates are calling for a rethink of the region’s devastated power systems. Rather than simply rebuilding grids that delivered mostly diesel generation via damage-prone overhead power lines, renewables advocates argue that the island grids should leapfrog into the future by interconnecting hundreds or thousands of self-sufficient solar microgrids.

“Puerto Rico will lead the way for the new generation of clean energy infrastructure. The world will follow,” asserted John Berger, CEO for Houston-based solar developer Sunnova Energy in a tweet before meeting in San Juan with Puerto Rico Governor Ricardo Rosselló this week. Rosselló appears to be on board, inviting Elon Musk via tweet to use Puerto Rico as a “flagship project” to “show the world the power and scalability” of Tesla’s technologies, which include photovoltaic (PV) rooftops and Powerwall battery systems.

Some power system experts, however, say the solar-plus-batteries vision may be oversold. They say that the pressing need to restore power, plus equipment costs and other practical considerations, call for sustained reliance on centralized grids and fossil fuels in the Caribbean. “They need to recover from the storm. Unfortunately I think the quickest way to do that is to go back to how things were before,” says Brad Rockwell, power supply manager for the Kauaʻi Island Utility Cooperative that operates one of the most renewable-heavy grids in the U.S.

Now is a tough time for a debate, given the ongoing power and communications blackouts afflicting many Caribbean islands, including Puerto Rico, the U.S. and British Virgin Islands, Dominica, and St. Martin. As of Thursday 12 October—more than three weeks after Maria’s cyclonic wrecking ball crossed the region—over four-fifths of customers in Puerto Rico and the U.S. Virgin Islands remained without power, according to U.S. Department of Energy status reports.

Puerto Rico lost major transmission lines that dispatched electricity generated at oil, coal, and natural gas-fired power plants on its lightly populated South shore to all corners of the territory. Its outage level actually slipped from 88.3 to 89.4 percent earlier this week after a tie line went down near San Juan. But it bounced back slightly, to an estimated 83 percent outage level, by yesterday.

What is clear is that several firms are trying to move fast while they talk, equipping rooftop solar systems with battery storage that enables consumers to operate independently of stricken grids. For example:

  • German storage system manufacturer sonnen launched a PV-plus-battery collaboration with local Aguadilla-based solar developer Pura Energía early this month;
  • Sunnova is crafting storage options for roughly 10,000 customers in Puerto Rico that it has already equipped with PV systems;
  • Tesla says it is sending “hundreds” of its Powerwall battery systems to Puerto Rico and, after reports of price gouging by independent installers, plans to dispatch experienced installers from the mainland to expand its local teams.

Peter Asmus, a microgrids analyst with Navigant Research, says that such solar microgrids will deliver power to solar system owners far faster than grid restoration, which is still months away for many customers. He says microgrids will also make the island systems more resilient in the long run.

Asmus sees the situation as reminiscent of post-war Europe, when devastated European grids left a vacuum that enabled something better. “They built a more advanced grid than we have in the U.S.,” says Asmus. He says the Caribbean has a similar opportunity today: “The infrastructure was devastated so severely. They can start over with a cleaner slate.”

Some suppliers see microgrids actually supplanting some of the region’s largest transmission lines. “The grid in Puerto Rico will never be built back the way it used to be,” wrote John Merritt, applications engineering director for Austin, Texas-based Ideal Power in an email to IEEE Spectrum. Ideal Power’s multi-port power converters enable microgrids to efficiently swap power between their alternating current and direct current components, including PV systems, generators, and storage batteries.

Giving up big transmission lines sounds optimistic to Rockwell at the Kauaʻi Island Utility Cooperative (KIUC). It would, he says, represent a major system overhaul and thus lost time that Puerto Rico’s residents and economy can ill afford. “The people of Puerto Rico are not going to want to withstand any more delays than they have to while people figure out how to rebuild in a different way,” he says.

Rockwell adds that batteries are still a rather costly way to balance variable renewable generation. He speaks from experience. KIUC’s grid is over four-fifths solar-powered during some midday hours. Several utility-scale storage systems help integrate such a high degree of  variable power by quickly covering for lost PV generation when clouds pass overhead or by absorbing surplus midday generation and discharging it after the sun sets. But Rockwell says high battery costs mean KIUC still relies heavily on its diesel power plants.

Merritt at Ideal Power acknowledges that the same is true for microgrids. Integrating solar can cut an island microgrid’s fuel consumption by 60 to 70 percent, slashing operating costs and pollution, but he says diesel generators remain “important” assets. “Moving a site from 24/7 diesel-powered microgrid to a 24/7 solar + storage microgrid would be cost prohibitive in most cases,” says Merritt.

There are also questions about PVs’ hardiness. Harvey, Irma, and Maria left many PV systems in shambles. Merritt says that a microgrid for a commercial facility on Saint Croix that Ideal Power participated in assembling before storms is operating without its six 33-kilowatt solar arrays. While they are out of commission for the next few months, the microgrid is relying solely on its diesel generators, battery, and converters.

Some utility-scale solar plants also took a beating, especially Puerto Rico’s Humacao solar array. PV panels shattered and flew out of their frames when Maria’s Category-4 winds ripped over the Humacao solar plant, where its French owner Reden Energie was in the process of doubling capacity from 26 to 52 megawatts.

Houston-based microgrid developer Enchanted Rock advocates rugged microgrids supported by natural gas, which is cheaper and cleaner than diesel and more reliable than both diesel and solar during heavy weather. “You can build community-type microgrids that have some combination of natural gas generation, solar and storage,” says Enchanted Rock CEO Thomas McAndrew.

Enchanted Rock made a name for itself during Hurricane Harvey when its natural gas-powered microgrids at Houston-area grocery stores and a truck stop turned into hubs for first responders and weary residents. Diesel deliveries were hard to come by for 4-5 days, says McAndrew, but natural gas kept flowing underground throughout the storm.

At present few Caribbean islands have access to natural gas, and even Puerto Rico’s gas infrastructure is limited to one liquefied natural gas (LNG) import terminal that pipes the fuel to two power plants. Rosselló had been working to expand LNG imports so more of its oil-fired power plants could burn gas.

Enchanted Rock’s McAndrew favors a network to distribute the gas instead, which he says would be cheaper than putting power lines underground to protect them from weather. He acknowledges that his proposal is ambitious, but says the outside investors that Puerto Rico will need to attract to support its revival can insist on infrastructure that will survive future storms. As McAndrew puts it: “Whether it’s private or government money, there’s got to be some sense that we might want to do this differently so we don’t just end up rebuilding it every couple of years.”

This post was created for Energywise, IEEE Spectrum’s blog about the future of energy, climate, and the smart grid

Advertisements

Seattle’s Bullitt Center Shines

Online at Architectural Record:

The designers of Seattle’s Bullitt Center have overachieved. The designers set out to demonstrate that a six-story office building could generate all of the energy it needs, but after one year of operation, it is sending a sizable energy surplus to the local power grid, according to data released by its developer, the Bullitt Foundation.

Consumption is simply far lower than what its architects and engineers projected for the 52,000-square-foot building. Instead of using 16kBtu per square foot—half the energy-use intensity (EUI) of Seattle’s best-performing office building—consumption during its first year was just 10kBtu/sf …

read on

Minnesota Finds Net Metering Undervalues Rooftop Solar

Utilities should be paying more for their customers’ surplus solar power generation according to a solar pricing scheme approved by Minnesota’s Public Utility Commission last month and expected to be finalized in early April. Minnesota’s move marks the first state-level application of the ‘value of solar’ approach, which sets a price by accounting for rooftop solar power’s net benefits, pioneered by the municipal utility in Austin, TX.

Minnesota is one of 43 U.S. states that requires utilities to pay retail rates for surplus solar power that their customers put on the grid. Utilities across the U.S. are fighting such net metering rules, arguing that they fail to compensate the utility for services that their grid provides to the distributed generator. So last year pro-solar activists and politicians in Minnesota called the utilities’ bluff, passing legislation tasking the state’s Department of Commerce with calculating the true value of rooftop solar power. Continue reading

Vertical Farming Grows Up

Plantagon's integrated office-farm

Plantagon’s integrated office-farm

Community-gardening advocates have sold urban farming as a sustainable local alternative to industrial-scale farming and as an educational platform for healthier living. And municipalities are buying in, adopting urban ag to transform vacant lots into productive civic assets. In the last two or three years, however, entrepreneurial urban farmers have opened a new frontier with a different look and operating model than most community gardens. Their terrain is above the ground, not in it. Working with help from engineers, architects, and city halls, they have sown rooftops and the interiors of buildings worldwide. “There’s a lot of activity right now, and there is huge potential to do more of it,” says Gregory Kiss, principal at Brooklyn-based architecture firm Kiss + Cathcart. Continue reading

Listening to Building Occupants

Power to the People

Sabotage: GreenSource’s how-to guide for occupants

New technology lets occupants work with building systems rather than against them, to improve their comfort while reducing energy costs.
By Peter Fairley

The stats on occupant comfort are disappointing, and green buildings are no exception. Consider, for example, heating and cooling performance. Thermal-comfort standard standards stipulate that such systems should satisfy at least four out of five occupants. “Very few buildings actually perform that well,” according to John Goins with the Center for the Built Environment (CBE) at UC Berkeley. Out of the 609 buildings in CBE’s database, only 13 percent meet ASHRAE’s performance threshold; among those that are LEED-certified, 20 percent make the grade.

There is increasing recognition that all that discomfort may be translating into a lot of wasted energy. Goins estimates that the average office building wastes 4 percent of its energy just by cooling and heating more than occupants want. The indirect impact could be even bigger when one considers how disgruntled occupants—who in most buildings lack an effective channel for requesting change—fight back against the machine. They may block air vents or plug in space heaters to combat excessive air-conditioning…

Excerpted from the May/June edition of GreenSource Magazine. Read the story at GreenSource.

Building-in a Force of Nature

Turbine House: Design by Michael Pelken & Thong Dang

Turbine House: Michael Pelken & Thong Dang’s residence with horizontal-axis wind turbine

As design teams work toward harnessing air flows around buildings, they are producing some intriguing structures. But just how viable is wind power as a source of on-site renewable energy?
By Peter Fairley

Wind power is the fastest-growing source of megawatts thanks to the jumbo-jet-sized turbines sprouting en masse worldwide. But it also has a significant presence in the city, where gusts regularly send umbrellas to landfills. Rather than considering it a nuisance, architects increasingly view urban wind as a renewable resource for on-building power generation.

Building-integrated wind power (BIWP)—wind turbines mounted on or incorporated within an occupied structure—may lack wind farms’ economies of scale. But like the leading source of on-building renewables—photovoltaics (PVs)—wind turbines offer some advantages in architectural applications. No roads get cut through wilderness to erect towers, and they deliver electricity without power lines and transmission losses. Wind turbines are also attractive to designers and clients looking to express a commitment to sustainability.

Such benefits provide potential for dramatic growth, says mechanical engineer Roger Frechette, principal in the Washington, D.C., office of Interface Engineering. “If there’s data showing that BIWP works and testimony that it’s a good thing to do, there will be an explosion,” he predicts…

Published in the April 2013 issue of Architectural Record Magazine. Read the whole story.

Digging into Miami’s Turkey Point Nuclear Power Station

The Society of Environmental Journalists’ Miami conference energy tour forged forward today, pursuing better understanding of South Florida’s energy options in spite of a disinvitation by local nuclear reactor operator Florida Power & Light. Continue reading