The buyer is the city of Farmington and the existing power plant was identified as the city owned-and-operated Bluffview Power Plant. According to a signed equipment supply contract, the contract is worth approximately $13.9 million. Wärtsilä equipment for the project, including the generator sets and auxiliary equipment, is expected to be delivered by January 2025.

The two Wärtsilä 34SG natural gas-fueled engines selected for this project are also capable of operating on biogas, synthetic methanol and a hydrogen blend.

MORE: Exploring the hidden value of reciprocating engines using sub-hourly grid modeling

Farmington Electric’s Bluffview Power Plant produces approximately 60 MW. It is a combined-cycle natural gas plant that was completed and commenced operation in May of 2005. The plant includes a natural gas-fired gas Combustion Turbine Generator (CTG) with a heat recovery steam generator (HRSG),
duct burner and steam turbine. The facility also includes cooling towers, circulating water pumps, sub-station, and supporting equipment to produce and deliver electricity

Wärtsilä said the new expansion will replace lost generating capacity following the closure of a coal-fired power plant. The last unit of the San Juan Generating Station, located in Farmington, was officially removed from service in September 2022.

The shutdown of San Juan Unit 4 followed the retirement of Unit 1 in June 2022. The coal-fired plant had four units but was reduced to two in 2017, with the closure of Units 2 and 3. The plant’s first unit was brought online in 1973.

Public Service Company of New Mexico (PNM) is the majority owner of San Juan Generation Station, but the city of Farmington has a 5% stake. The city had aimed to keep the plant open, partnering with Enchant Energy for a carbon capture and sequestration (CCS) project

The project is intended to showcase how leveraging existing infrastructure with electrolyzers and fuel cell technology may be able to create microgrids that deliver resilient power and can help safeguard businesses, communities and campuses from power disruptions.

This project takes water from Caltech’s service line and runs it through Bloom Energy’s solid oxide electrolyzer, which uses grid energy to create hydrogen. The resulting hydrogen is injected into Caltech’s natural gas infrastructure upstream of Bloom Energy fuel cells, creating up to a 20% blend of hydrogen and natural gas. All of this fuel blend is then converted into electricity with Bloom Energy’s fuel cells, and the electricity is then distributed for use on campus.

Unlocking Hydrogen’s Power Potential is an educational track at the POWERGEN International® exhibition and summit, which serves as an education, business and networking hub for electricity generators, utilities, and solution providers engaged in power generation. Join us from January 23-25, 2024, in New Orleans, Louisiana!

SoCalGas is working to help develop a state hydrogen blending standard by proposing pilot projects for approval by the CPUC. These projects could help to better understand how clean fuels like clean renewable hydrogen could be delivered through California’s natural gas system.

Earlier this year, SoCalGas unveiled its H2 Innovation Experience demonstration project designed to show the potential resiliency and reliability of a hydrogen microgrid.

Enchanted Rock, a microgrid developer, and U.S. Energy, a vertically integrated energy solutions provider in refined products, alternative fuels, and environmental credits, announced a partnership to provide backup power to the Microsoft facility.

The data center will use Enchanted Rock’s electrical resiliency-as-a-service and ultra-low-emission generators to avoid disruptions to their operations.

Unlocking Hydrogen’s Power Potential is an educational track at the POWERGEN International® exhibition and summit, which serves as an education, business and networking hub for electricity generators, utilities, and solution providers engaged in power generation. Join us from January 23-25, 2024, in New Orleans, Louisiana!

The resiliency microgrid, utilizing carbon-neutral RNG, is meant to ensure maximum uptime for Microsoft’s San Jose data center by providing backup power during grid outages. U.S. Energy will deliver RNG sourced from diverted food waste that would have otherwise ended up in landfills. The RNG will be injected upstream in the pipeline to match natural gas usage at the site and reduce overall greenhouse gas emissions, supporting Microsoft’s goal to become carbon-negative by 2030, the companies said.

The agreement also allows for flexibility in the amount of RNG supplied, ensuring the data center can meet its standards for emissions reduction. Procurement of the RNG is scheduled to begin in early 2026. 

The RNG market is rapidly growing along with burgeoning interest in all forms of clean energy. Timing-based incentives for the market, such as those included in the Inflation Reduction Act of 2022, put a premium on designs that are adaptable, reliable, affordable, and constructible.

Because RNG remains an emerging market, many owners and operators of RNG facilities are designing and developing them for the first time. Reliability is critical for RNG facilities — including biogas generation, upgrading, and processing, as well as pipeline interconnects — because any downtime will require flaring of biogas, leading to additional emissions and loss of potential revenue. Keeping total installation costs low is also vital to justifying the business case for building a facility.

Read more about how to leverage a standardized design approach in RNG facility projects here.

A pair of community microgrid projects in Massachusetts are already helping to inspire similar projects in the state before construction has even begun.

The city of Chelsea and Boston’s Chinatown neighborhood are each developing projects that supporters hope can become powerful case studies for the potential of microgrids to increase resilience and create other benefits for residents.

Chelsea has ordered equipment for a microgrid that will connect municipal facilities, and is targeting a construction date in the second half of 2024. Chinatown is finalizing plans for a system to provide solar power and backup energy storage to a 200-unit affordable housing apartment building. 

“We do see this serving as a model for the nation if we can pull it off,” said Alexander Train, Chelsea’s director of housing and community development.

The list of communities considering whether to follow their lead includes Cambridge, Lynn, and Milton.

In the broadest sense, microgrids are small-scale energy systems in which power is produced, distributed, and consumed, typically all within a self-contained area such as a college campus or hospital complex. Microgrids can often operate independently from the main grid, providing continuous power, even in case of disruptions to the regional supply, and can help cut energy costs. 

Though they come in all configurations and sizes, microgrids have historically generated power with fossil fuels. But as the transition to sustainable energy accelerates, more organizations are looking at ways to combine renewable energy and battery storage to create cleaner microgrids. 

A unique model

Several years ago, semi-retired engineer David Dayton saw in this evolving model an opportunity to improve the health and safety of environmental justice communities — areas that bear a disproportionate environmental burden and are often home to many low-income residents and people of color. 

Solar panels could cut energy costs, while batteries could provide power to critical facilities, such as municipal buildings, community centers, and senior housing, in case of power outages. Batteries could also be used to sell power back to the main grid to help pay for the system.

To get this vision off the ground, Dayton reached out to organizations he was familiar with, including the Green Justice Coalition and private companies Peregrine Energy Group and Synapse Energy Economics. The participants identified Chelsea and Chinatown as good candidates for a community microgrid. Both communities have high populations of immigrants and people of color, and both have median household incomes well below the average for the area. And they are vulnerable to climate change impacts including flooding and dangerous temperatures as the result of the urban heat island effect. 

In 2018, the group Dayton assembled acquired grants from the Massachusetts Clean Energy Center for feasibility studies in the two communities.

The model developed during this process proposes to create the nation’s first community-owned “virtual microgrid.” The designs use cloud-based software to connect solar installations and batteries in locations that aren’t necessarily adjacent to each other, a departure from the conventional model in which the components of the microgrid are physically connected. This approach allows more flexibility in deciding what facilities can participate, particularly helpful when a community would like to include vital facilities that are geographically spread out. 

“It’s a microgrid without borders,” Dayton said. “We can add any building to the network at any time — they don’t have to be contiguous.”

Today, the first two projects are making progress. In Chelsea, a design has been created that includes 500 kilowatt-hour batteries at both the police station and city hall, as well as a 400 kilowatt solar array at the department of public works facility. Plans are already in the works to start gathering more community input by the end of the year about expanding the system to other essential locations such as senior housing, churches, or health care centers. 

“We want this system to proliferate as fast as we possibly can,” Train said.

In Chinatown, project developers have had to scale back their initial ambitions of connecting several multifamily housing buildings. They are now focused on serving Masspike Towers, a privately owned development of 190 affordable units, before expanding. The plan, still being finalized, is to build a solar installation and share the savings across all residents in a model similar to community solar. Battery storage will help keep common areas powered and extensive energy efficiency measures will reduce overall consumption. 

“Our goal is to bring the benefits of clean energy and decarbonization incentives to a low-income urban community that has historically missed out on a lot of those benefits,” said Lydia Lowe, executive director of the Chinatown Community Land Trust, one of the community partners in the project

Learning lessons

As work has progressed in Chelsea and Chinatown, other communities have started to wonder about the possibilities. And the two ongoing projects are offering valuable lessons about how to make community microgrids work. 

Financing has emerged as a potential major sticking point. In Chelsea, where the city will own the system, the city council voted to provide $4 million in funding to the project. That money – along with federal support, the savings created by solar generation, and the revenue from selling stored powerback onto the grid – is enough to get the project up and running. Building on municipal sites that each have only one tenant also helps simplify the design and logistics. 

In Chinatown, however, the city is providing some funding, but not enough to cover the entire project, making it more challenging to structure the financing in a way that is affordable yet satisfies potential investors. 

“It is a little bit tougher. We were able to get the city on board in Chelsea,” said Sari Kayyali, microgrid manager for the two projects. “We’ve been working with them to find a workable scope that can pay back investors in a timely manner.”

The work thus far has also highlighted the importance of the community-led ethos that distinguishes the approach from other microgrids, which are generally privately owned and operated. From the beginning, Dayton and other planners felt it was essential to the underlying mission of environmental justice that community members have a lot of say in determining the goals, design, and operations of these community microgrids. In both Chelsea and Chinatown, the planners divided the $75,000 each community received, dedicating half to engineering and technical planning, and giving the other half to community organizations to conduct outreach and education. 

In Chelsea, these efforts were key to securing the microrid’s future: The strong support of the community helped sway a few skeptical city councilors to vote for funding for the project, said Elena González, technical director of Climable, a nonprofit that has conducted community engagement and outreach for Chelsea, Chinatown, and Cambridge.

But the importance of community involvement is far more than just strategic, supporters said. 

“These microgrid projects empower communities and give them a role in the way that energy development happens,” González said. “This is something that has a huge impact in people’s lives and it is important that the community leads.”

This article first appeared on Energy News Network and is republished here under a Creative Commons license.

In 2020, the U.S. Department of Energy Solar Energy Technologies Office (SETO) awarded nearly $4 million to a team at Oak Ridge National Laboratory to develop an optimized solution to manage the distribution of electricity within a network of solar-powered microgrids. The team developed a microgrid orchestrator— software designed to manage the exchange of power between multiple microgrids within a network. The team is in the final stages of hardware testing before demonstrating the microgrid orchestrator in the mountain town of Adjuntas, Puerto Rico.

Two community-owned microgrids will soon provide solar power to Adjuntas, even when blackouts occur in other parts of the island. Adjuntas did not have power for six months because of Hurricane Maria in 2017. Local community organization Casa Pueblo partnered with the nonprofit Honnold Foundation to install the town square microgrids to ensure that Adjuntas residents have access to critical services in the aftermath of future natural disasters.

When Hurricane Fiona hit Puerto Rico in September 2022, a smaller, previously-installed Adjuntas microgrid that serves Casa Pueblo kept the power on for nine days when other parts of the island went dark. Researchers will work to advance the orchestrator’s capabilities to extend electric service as long as possible for future outages.

The DOE says the success of this microgrid orchestrator could result in the creation of microgrid networks in communities across the nation to increase resilience, reduce greenhouse gas emissions, and support energy independence and security.

The DOE also recently announced a $14.7 million Funding Opportunity Announcement (FOA) for multi-year research, development, and demonstration of microgrid-related technologies, with the goal to bring microgrid solutions to underserved and Indigenous communities in remote, rural, and islanded regions in the United States.

With this FOA, DOE’s Office of Electricity’s research partners will develop and demonstrate microgrid-enabling technologies, including renewable generation and storage systems, multi-nodal small-scale high-voltage direct current, advanced demand-side management strategies, and microgrid control systems. The FOA also includes opportunities to address non-technical barriers to deployment of microgrids in these communities, such as lack of local technical expertise and supply chain challenges.

Originally published in Power Grid International.

This week, the project received some additional assistance.

The United States Department of Energy (DOE) recently announced that Valley Children’s, the California Energy Commission (CEC) and Faraday Microgrids are the recipients of a long-duration energy storage demonstrations grant to accelerate and expand the healthcare network’s clean energy storage capabilities. This microgrid at Valley Children’s is one of just 15 projects chosen as part of the DOE’s $325 million commitment to fund similar projects nationwide that promote the adoption of renewable energy resources and advance clean air technologies. Valley Children’s microgrid will consist of solar photovoltaic materials, fuel cells, and battery storage.

“At the heart of Valley Children’s sustainability plan is our kids. Valley Children’s must ensure we always have a source of energy to care for them and their families under any circumstance or through any disruption – and we have a responsibility to improve the communities where our children live, learn and play,” says Valley Children’s President and CEO Todd Suntrapak. “The Department of Energy grant represents a transformative moment for Valley Children’s and for our communities, and places us at the forefront of creating safe, effective and reliable power systems for hospitals here and around the world.”

Valley Children’s project, to be engineered by Mazzetti and built by renewable microgrid developer, Faraday Microgrids, is expected to receive $30 million from the DOE and an additional $25 million from the CEC. At the project’s completion, Valley Children’s is projected to operate the largest renewable energy microgrid in the country, connected to a hospital emergency system.

Over the next several months, the DOE, CEC, Faraday Microgrids and Valley Children’s will finalize the terms of the grant.

Meanwhile, work continues on phase 1 of Valley Children’s renewable energy microgrid. When online and operational in 2025, the renewable energy microgrid will reduce reliance on the traditional power grid, ensuring Valley Children’s Hospital and buildings on its campus remain operational in the event of power outages in the region. It will also cut carbon emissions by more than 50%.

Valley Children’s, one of the first hospitals to sign the White House-HHS Health Sector Climate Pledge, has also committed to achieving net zero by the year 2050, meaning the entire campus will produce no carbon emissions.

Valley Children’s Hospital in Madera, California aims to replace diesel generators with cleaner sources yet ensure uninterrupted power supply.

Australia-based Redflow will collaborate with Faraday Microgrids on the project, named the Children’s Hospital Resilient Grid with Energy Storage (CHARGES).

The project is receiving funding from the U.S. Department of Energy (DOE) for 15 long-duration energy storage projects across 17 states and one tribal nation. The $325 million LDES program comes from the Infrastructure Investment and Jobs Act (IIJA). The awards were announced last week.

CHARGES is sponsored and expected to be co-funded by the California Energy Commission (CEC).

Valley Children’s Hospital, located in California’s Central Valley, frequently faces extreme environmental challenges, including heatwaves, droughts, smog and poor air quality. California has a goal of installing 45-55 GW of long-duration energy storage by 2045 to support grid reliability and clean energy adoption.

The microgrid system is designed to safeguard critical hospital operations during utility outages, ensuring at least 18 hours of continued functionality following earthquakes or other natural disasters.

Redflow’s systems are based on zinc-bromine flow battery chemistry. Flow batteries use liquid electrolytes that flow through the battery cells during charging and discharging processes. Zinc is the primary element in the Redflow battery’s anode, while bromine is used in the cathode.

The collaboration agreement aims to address emissions reduction at airport buildings, horizontal airport infrastructure, vehicles and aircraft systems.

Baker Hughes’ portfolio includes both hydrogen-ready turbines and heat recovery solutions for microgrid applications.

Avports currently manages 11 airports in seven different U.S. states. The company has operated more than 30 airports, aviation facilities and passenger terminals in the U.S., including for more than 50 years in New York State.

Lower pressure boilers still must be handled with care

Figure 1 provides a basic schematic of a common co-generation configuration.   

Figure 1. Generic flow diagram of a co-generation system. The blowdown heat exchanger and feedwater heater may not be present in some configurations. Note the multiple condensate return lines. Illustration courtesy of ChemTreat, Inc. 

Depending on boiler pressure and design, and the processes served by the boiler steam, makeup treatment may range from sodium softening to reverse osmosis to perhaps even the high-purity arrangements outlined in Part 1. For steam generators under 600 psig pressure, sodium softening, often combined with downstream equipment for alkalinity removal, is common. Figure 2 below is an extract taken from the recent revision of the American Society of Mechanical Engineers (ASME) industrial boiler water guidelines ⁽¹⁾. This extract provides insight on impurity level limits for low- to medium-pressure water tube industrial steam generators. The complete guidelines are available from the ASME at very reasonable cost and should be in the library of any industrial plant with steam generators.

Figure 2. Data extracted from Table 1, Reference 1 – “Suggested Water Chemistry Targets Industrial Water Tube with Superheater”

While power plant chemists are (or should be) familiar with stringent requirements for their high-pressure units (which we will return to in later parts of this series), several guidelines in this extract stand out for lower-pressure boilers. These include:

• Low feedwater hardness, dissolved oxygen, total iron, copper, and total organic carbon (TOC)
• Feedwater pH ranges designed to protect most metals. (Operation near the lower-end of the range is common to project copper alloys.)
• The long-standing philosophy of allowing some bicarbonate alkalinity (HCO₃^–) in the boiler water, but which may influence condensate return chemistry.
• A strong emphasis on steam purity, which is in part a function of boiler water impurity concentrations, thus the increasingly stringent boiler water contaminant guidelines as a function of increasing pressure.

 Let us consider these items in greater detail with help from References 2 and 3.

Hardness Excursions

A very common comment/question that steam generation chemistry experts receive from industrial boiler operators is, “We are suffering repeated boiler tube failures, can you help us find the source.” One of the first items a specialist will typically examine is the sodium softener. Time after time, the consultant will learn that softener upsets have been common but that the plant continues to operate with out-of-spec makeup water going to the boiler. Figures 2 and 3 illustrate the typical result of softener upsets and malfunctions.

Figure 4.  Bulges and blisters in a boiler tube from overheating due to internal deposits.  Photo courtesy of ChemTreat, Inc.

A common malady at many plants, which this author has directly observed on several occasions, is an intense focus by plant personnel on process chemistry and engineering with insufficient attention to steam generators (and cooling systems) until failures begin to cause unit shutdowns that affect production. Water and steam are the lifeblood at many plants, and to neglect these systems puts plant operation and sometimes employee safety at peril.

Apart from hardness capture, even well-operated sodium softeners by themselves remove no other ions from the makeup water. In low-pressure boilers with good blowdown control, most impurities may be manageable. However, issues regarding alkalinity (the alkalinity in raw water is usually in the bicarbonate, HCO₃^–, form) deserve additional discussion.

HCO₃^–, upon reaching the boiler, in large measure converts to CO₂ via the following reactions:

2HCO₃^– + heat → CO₃^2- + CO₂↑­ + H₂O                                             Eq. 1

CO₃^2- + heat → CO₂↑­ + OH^–                                                              Eq. 2

The conversion of CO₂ from the combined reactions may reach 90%. CO₂ flashes off with steam, and when the CO₂ re-dissolves in the condensate can increase the acidity. 

CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃^–                                                 Eq. 3

Long-term carbon-steel corrosion may be the result.

Figure 5.  Carbonic acid grooving of a condensate return line. Photo courtesy of ChemTreat, Inc.

Furthermore, the iron oxide corrosion products will transport to the steam generators and form porous deposits on boiler tubes and other internals. These precipitates can become sites for under-deposit corrosion (UDC) fed by impurities in the boiler water. UDC generally increases in severity with increasing boiler pressure and temperature. At high-pressures, UDC can lead to hydrogen damage, a very insidious corrosion mechanism. 

Some sodium-softened makeup systems also have a forced-draft de-carbonator or split-stream de-alkalizer to remove most of the bicarbonate alkalinity, but even with this equipment the remaining dissolved ions in the raw water still enter the boiler makeup. These impurities reduce the allowable cycles of concentration in the boiler, which leads to increased blowdown. If not properly monitored and controlled, they may cause corrosion or increase the dissolved solids concentration in the boiler steam. Accordingly, becoming more popular is reverse osmosis (RO) for makeup water treatment. Even single-pass RO will remove 99% or greater of the total dissolved ions in the makeup water.

Figure 6. Basic design of a single-pass, two-stage RO. The designation two-stage comes from treatment of the first stage reject in a second stage. (3)

As we discussed in Part 1, addition of a second pass to the RO system with downstream polishing by ion exchange or electrodeionization produces makeup suitable for even the highest-pressure steam generators.

The wild card for co-gen units – Condensate return

Steam generators that solely produce power nearly represent (usually) a closed circuit. A tight system may only have 1% water loss. The most common source of impurity ingress is a leaking tube or tubes in the steam surface condenser. (Units with air-cooled condensers offer other factors to consider.) So, with a good on-line chemistry monitoring system and attentive plant personnel, upsets can usually be quickly corrected. The situation is frequently much different in co-gen units, where condensate could be coming back from any number of chemical heating/reaction processes. Consider the following case history.

A number of years ago, the author and a colleague were invited to an organic chemicals plant that had four 550-psig package boilers with superheaters. The steam provided energy to multiple plant heat exchangers, with recovery of most of the condensate. Each of the boiler superheaters failed, on average, every 1.5–2 years from internal deposition and subsequent overheating of the tubes. Inspection of an extracted superheater tube bundle revealed deposits of approximately ⅛–¼ inches in depth. 

Additional inspection revealed foam issuing from the saturated steam sample line of every boiler, whose cause became quickly apparent. Among the data from water/steam analyses performed by an outside vendor were total organic carbon (TOC) levels of up to 200 mg/L in the condensate return. Contrast that with the <0.5 mg/L feedwater TOC recommendation in Figure 2. No treatment processes or condensate polishing systems were in place to remove these organics upstream of the boilers. Based on the TOC data alone, it was easily understandable why foam was issuing from the steam sample lines, and why the superheaters rapidly accumulated deposits and then failed from overheating.

To protect steam generators from what could be a wide variety of impurities, careful planning is needed to determine, among others, what contaminants and in what concentration may be in the return condensate, can the impurities be economically removed by some form of condensate polishing system, and what streams may need diversion directly to the wastewater treatment plant? The latter issue, of course, influences the size and treatment methods of the wastewater system. Also, condensate dumping to the WWT plant requires increased makeup water production and a larger system in that regard.

Another important issue with co-gen and industrial steam units is feedwater dissolved oxygen control.  In September and October of 2022, Power Engineering published a four-part series by the author on the importance of controlling flow-accelerated corrosion (FAC) in combined cycle heat recovery steam generators (HRSGs). ⁽⁴⁾ Because these high-pressure HRSGs require high-purity makeup (cation conductivity ≤0.2 mS/cm), and typically have no copper alloys in the feedwater system, the recommended chemistry calls for a small amount of dissolved oxygen (D.O.) in the feedwater with no oxygen scavenger (the better term is reducing agent) feed. For units with deaerators, it may be necessary to close the deaerator vents to help maintain a D.O. residual in the economizer circuits. Supplemental oxygen injection may also be required. For those who review this series, note that these guidelines are part of a feedwater chemistry program known as all-volatile treatment oxidizing (AVT(O)).

However, because the condensate return purity in co-gen and industrial steam generators often does not meet high-pressure feedwater guidelines, AVT(O) is usually not acceptable. The feedwater network may also contain heat exchangers with copper-alloy tubes, which further negates AVT(O) as a potential treatment program. Accordingly, a standard requirement is feed of an alkalizing amine to maintain pH within the range shown in Figure 2 plus mechanical deaeration and reducing agent/oxygen scavenger feed to maintain very low feedwater D.O. concentrations. This in turn necessitates accurate monitoring for feedwater iron (and at times copper) corrosion products to fine-tune chemical treatment programs. The author and colleagues have reported on these issues in previous Power Engineering articles. ^{(5, 6)}

Note:  The Electric Power Research Institute (EPRI) has published a comprehensive book on flow-accelerated corrosion that is offered to EPRI members and non-members alike. ⁽⁷⁾     

Conclusion

Co-generation is becoming increasingly popular for power production and process heating at many facilities, in large part because the net efficiency is much higher (and corresponding carbon dioxide emissions are lower) than for traditional power generation. ⁽⁸⁾ However, co-gen chemistry personnel often face additional challenges over those encountered by their power plant counterparts. Careful planning and good vigilance are necessary to minimize corrosion and fouling in these systems.

References

1. Consensus on Operating Practices for the Control of Feedwater and Boiler Water Chemistry in Modern Industrial Boilers, The American Society of Mechanical Engineers, New York, NY, 2021.
2. Buecker, B., Koom-Dadzie, A., Barbot, E., and F. Murphy, “Makeup Water Treatment and Condensate Return:  Major Influences on Chemistry Control in Co-Gen and Industrial Steam Generators”; presented at the 41^st Annual Electric Utility Chemistry Workshop, June 6-8, 2023, Champaign, Illinois.
3. B. Buecker (Tech. Ed.), “Water Essentials Handbook”; 2023. ChemTreat, Inc., Glen Allen, VA.  Currently being released in digital format at www.chemtreat.com.
4. B. Buecker, “HRSG Steam Generation Issues: Reemphasizing the Importance of FAC Corrosion Control, Parts 1-4”; Power Engineering, September-October 2022.
5. Buecker, B., and F. Murphy, “Breakdown:  Is Flow-Accelerated Corrosion a Concern in Co-Generation Steam Generators”; Power Engineering, October 2020.
6. Buecker, B., Kuruc, K., and L. Johnson, “The Integral Benefits of Iron Monitoring for Steam Generation Chemistry Control”; Power Engineering, January 2019.
7. Guidelines for Control of Flow-Accelerated Corrosion in Fossil and Combined Cycle Plants, 2017. Electric Power Research Institute, Palo Alto, CA, USA, 3002011569. While EPRI typically charges a fee for reports to non-EPRI members, this document is available at no charge due to the importance of safety for FAC understanding and mitigation.
8. B. Buecker, “A Thermodynamic Overview of Co-Generation and Combined Cycle Power vs. Conventional Steam Generation”; Power Engineering, March 2021.

Brad Buecker is president of Buecker & Associates, LLC, consulting and technical writing/marketing.  Most recently he served as Senior Technical Publicist with ChemTreat, Inc.  He has over four decades of experience in or supporting the power and industrial water treatment industries, much of it in steam generation chemistry, water treatment, air quality control, and results engineering positions with City Water, Light & Power (Springfield, Illinois) and Kansas City Power & Light Company’s (now Evergy) La Cygne, Kansas station.  His work also included 11 years with two engineering firms, Burns & McDonnell and Kiewit, and he also spent two years as acting water/wastewater supervisor at a chemical plant.  Buecker has a B.S. in chemistry from Iowa State University with additional course work in fluid mechanics, energy and materials balances, and advanced inorganic chemistry.  He has authored or co-authored over 250 articles for various technical trade magazines and has written three books on power plant chemistry and air pollution control.  He may be reached at beakertoo@aol.com.

The California Public Utilities Commission approved the project between Pacific Gas & Electric, the state’s largest utility, and energy storage provider Energy Vault on April 27.

PG&E and Energy Vault sought to use the battery plus green hydrogen long-duration energy storage system (BH-ESS) to power the downtown and surrounding area of Calistoga, a city in Northern California, for a minimum of 48 hours during planned outages and shutoffs due to high wildfire risk.

The system aims to provide a minimum of 293 MWh of dispatchable energy. Capacity could eventually be expanded to 700 MWh, which would allow it to operate for longer without refueling.

PG&E and Energy Vault expect the project to operate for 10.5 years starting in 2024. The project is expected to cost no more than $46.3 million. No parties in the CPUC proceeding objected to PG&E’s cost recovery and cost allocation plan.

PG&E selected Calistoga because, according to PG&E’s 10-year Lookback Analysis, the Calistoga substation has one of the highest frequencies of modeled direct impacts with safe-to-energize customers. PG&E noted eight direct transmission-level impacts in the 2021 update of the historic lookback analysis submitted to the CPUC.

The CPUC acknowledged, but rejected, objections from the Public Advisor’s Office within the commission that PG&E’s plan leaned too heavily on emerging technologies and a provider in Energy Vault that does not have sufficient experience.

California rules, however, allow for projects that are novel or not commercially tested. The onus is on PG&E to reject projects that it deems technologically infeasible.

In approving the PG&E application, the CPUC directed the utility to report on cost, performance, and learnings from the pilot project. The commission also said PG&E and Energy Vault should utilize the project, namely the battery storage system, to support typical grid operations when not in use as a microgrid.

“Energy Vault is pleased with the CPUC’s approval of our innovative microgrid project with PG&E in Calistoga,” Marco Terruzzin, Energy Vault’s chief commercial and product officer, said in a statement. “We are committed to supporting local communities to have access to resilient and clean power.”

Who is Energy Vault?

Energy Vault was founded by serial clean energy entrepreneur Bill Gross, who tapped Robert Piconi to lead the energy storage solution provider as its CEO and co-founder in 2017.

Energy Vault made its splash with an unconventional long-duration energy storage system that used a set of linked six tower cranes to lift and lower composite blocks. By 2020, Energy Vault had built and grid-connected a 5 MW/35 MWh commercial demonstration unit operating in Switzerland.

The company announced a Series B round of $110 million from the Softbank Vision Fund in 2019, which was followed by a $100 million Series C round in 2021. Energy Vault began listing on the New York Stock Exchange in 2022.

Today, Energy Vault’s first commercial gravity storage system is 75% complete. The 25 MW/100 MWh facility in Rudong, China. This facility ditches the cranes in favor of a standard building construction that protects against outside elements and simplifies the lifting system to improve round-trip efficiency. At around 80-85% RTE, the facility will be one of the most efficient energy storage systems in the world.

The principles for energy storage, however, remain the same. Composite blocks are moved vertically and horizontally to store energy, guided by advanced software.