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Boiler Efficiency for Reduced Carbon Emission and Cost
by Marcelle P. Villegas - April 01, 2021
A case study at the GNPower coal power plant in Mariveles, Bataan (Photo credit: https://www.gnpower.com.ph/projects/)
GNPower Ltd. Co. (or “GNPower”) is a private limited partnership that was organised and established in 1997 by PMR Holding Corp. as its sole general partner and PMR Limited Co. as limited partner. The company aims to develop, operate and own power generation projects and associated facilities in the Philippines. Through the years, there were changes in the corporate structure and partnerships. By June 2014, the sole general partner of GNPower is GNPower Holdings GP Corporation which is owned by Power Partners, while Power Partners is the sole limited partner.
With regards to their coal energy project, it started way back in 2005. On that year, the partnership began the development of a coal-fired project. It was their first step in creating an “integrated, multi-fuel electricity generation and fuel handling energy complex”. 
Five years later, the GNPower began the construction of a 2x316MW (net) clean pulverized coal-fired power plant located in Mariveles, Bataan, Philippines (“Mariveles Project”). In this project, GNPower and Power Partners own a significant minority position through their ownership of GNPower Mariveles Coal Plant Ltd. Co. (GMCP). GMCP is the special purpose vehicle established to construct, own and operate the Mariveles Project. 
In 2013, the coal-fired facility was declared commercially available in the market. It is GNPower’s pioneer project and is the largest greenfield power project that was built in Luzon after the enactment of EPIRA in 2001.
GNPower Mariveles Coal Plant Ltd. Co. is now referred to as GNPower Mariveles Energy Center Ltd. Co.
Coal is considered a baseload energy resource in the Philippines as it is sufficiently cost-effective in providing a consistent supply of power. Currently, there are 28 coal-fired power plants operating throughout the Philippines.  One competitive and significant factor in the industry is the plant’s ability to supply adequate power while burning less coal in the process. In relation to this, a study was conducted by a group of experts to determine how cost-efficient is the operation in the Mariveles Coal Plant. What are the possible strategies they can or have implemented to assure boiler efficiency that utilizes less coal? What is the significance of this study with regards to protecting the environment through reduced carbon emission?
“A Study of the Changes in Efficiency of a Coal Fired Boiler Following the Conversion to a Dry Bottom Ash Handling System” is a study done by Artemio Boado (Plant Manager, Mariveles Power Plant), Zhao Peng (Engineering Manager, Qingdao Daneng), Steven Hou (General Manager, Int’l Business of Qingdao Daneng), Wang Yong (Chairman, Qingdao Daneng) and Edgardo B. Cruz (President, Philippine Coal Plant User Group).
The study aims to determine and analyse the boiler efficiency of Unit 2 of Phase 1 of GN Power Mariveles, according to measured data before and after the conversion of the bottom ash system from wet to dry which was implemented in March 2018. 
From their report, GN Power Mariveles Phase 1 consists of 2 x 340 MW T-fired sub critical coal fired boilers (Originally 2 x 316MW). The boilers were supplied by Harbin Boiler Company of China. This has a wet bottom handling system which consisted of a hopper under the boiler, sealing plate, submerged scraper conveyor, cooling water system, silo and discharger. The wet system was later converted to dry system by Qingdao Daneng Environmental Protection Equipment Incorporated Company (or Qingda) utilising their patented DUNOCON conveyor technology. “Both units were converted and commissioned in a standard scheduled 30-day boiler outage with Unit 2 converted in March 2018 and Unit 1 in February 2019. Since commissioning, both units dry bottom ash systems have operated well and without issue.” 
“When considering a pulverised coal fired boiler, the application of dry bottom ash handling technology is well proven and has several key advantages over those utilising water for the cooling and transportation of bottom ash. Along with the elimination of water handling and treatment, reduced power consumption, reduced maintenance etc, a significant amount of energy can be returned to the boiler from the reduction of energy losses at the boiler throat, waste heat from the bottom ash and the reduction of unburnt carbon in the bottom ash.” 
“However, in order to realise these potential benefits, the dry bottom ash system needs to be carefully designed and operated to ensure that the cooling air quantity and distribution through the conveyor and into the boiler are optimised.” 
Boiler efficiency testing standard
For this study, the efficiency of the boiler unit is determined basically by following the testing standard ASME PTC-4.1. (Further calculation methods not considered in ASME PTC-4.1 have been supplemented to compute for the credits specifically due to the adoption of dry bottom ash technology. )
There are two ways to compute for the boiler efficiency testing: (1) direct method (2) indirect method.
Direct method is obtained by the ratio of energy gain of working fluid (water or steam) compared to the energy input into the boiler. Here is the formula they used:
Comparative analysis of boiler efficiency
(1) Direct method
Based on Table 1 and Figure 2, that coal consumption has reduced by an average of 2.12% over a boiler load range of 320 MW to 340 MW since the retrofit conversion of Unit 2 to a Dry Bottom Ash System. Table 2 is the operating data from the owner with the boiler load between 339 and 340 MW which can be used to calculate the boiler efficiency using the ASME PTC4.1 direct method. 
(2) Indirect Method
For the Indirect Method, the study explored the various factors in measuring the efficiency of the boiler system. These factors include:
a) dry flue gas heat loss
Dry flue gas heat loss is the main reason of boiler heat loss. Using formula (2), various heat losses are discussed here:
Based on this data, there is no significant change in the flue gas temperature at the inlet of air preheater, and the oxygen content decreases. With the help of the advanced air control DUNOCON system, “the cooling air quantity is controlled quantitatively to the maximum extent”, thus no excess air enters the boiler through dry bottom ash handling system. The other dry system has multiple air doors, but DUNOCON has only one air door on the head of the conveyor which is interlocked with the ash temperature of conveyor outlet. As an effect, “the cooling air quantity has been limited to maximum extent under the premise of ensuring the ash cool down effect”.  The DUNOCON also has a special penetration heat transfer design that improves the cooling efficiency and reduces the need for cooling the air. In addition, this helps the unburned carbon at the bottom ash re-burn and recovers its heat.
In this part of the study, the boiler efficiency is increased by 0.382%.
Other factors under indirect method:
b) heat loss due to evaporation of water formed due to H2 in the coal,
c) heat loss due to H20 in the coal
d) heat loss due to H20 in the air
e) heat loss due to incomplete combustion of combustible gas
“The heat loss due to the incomplete combustion is principally concerned with the losses resulting from incomplete combustion of the gaseous products such as CO, H2 and various other hydrocarbons which can potentially be found in the flue gas of a boiler. Considering Mariveles Unit 2 is a large modern Utility Boiler, then we will assume that the losses through the incomplete combustion of gases is negligible for this study.” 
f) heat loss due to Boiler Surface Heat Loss, Radiant Heat Loss, and Convective Heat Loss
“This study assumes that the Boiler Surface Heat Loss and Convective Heat Loss will not be have been affected by the changes to the bottom ash system. However, due to the change from wet system to dry system, the radiant heat at the boiler throat is recovered back to the boiler by the cooling air.”
Based on their calculations, the boiler efficiency is increased by 0.11% because of the radiant heat recovered through the cooling air.
g) heat loss due to unburnt in fly ash
i) heat loss due to bottom ash in the wet system
All the bottom ash is cooled by the water. As a result, there is a loss of all the sensible heat associated with the bottom ash. In comparison, the dry system uses the cooling air to recover the bottom ash sensible heat and reintroduces it to the boiler. In addition, part of the unburned carbon in the ash can burned during the transportation process and the heat will be recovered by cooling air. Also those heat generated improves the boiler efficiency.
Regarding the carbon combustion quantity during the conveying period, the study reported the following test list:
Carbon content in wet ash 4.59%
Carbon content in dry ash 3.5%
This shows that about 1.09% of the carbon in the dry bottom ash reburns and releases heat. Those heat is also brought back to the boiler by the cooling air. The unique penetrating cooling action of the DUNOCON system increases the contact area between the bottom ash and the cooling air, and increases the combustion probability of carbon. Qt=174876 KJ/hr From the formula (16), the boiler efficiency increase R2=0.016%. 
To sum up, the efficiency of the boiler is increase by 0.51% after the retrofit in indirect method.
Cost and energy conservation
a) From the table 1, the average coal consumption before and after the retrofit of boiler is 208t/h and 204.45t/h under 330~340MW. Assuming that the annual operating time of 8000h, the annual coal saving is about 28,400t. 
b) Comparing this with the wet bottom ash handling system, the dry system has no circulating water system, thus the system is simpler and the operation is fully automatic. Additionally, the power consumption of dry system is lower than wet system.
c) After the retrofit, the daily maintenance work of dry system is almost zero. Compared with the wet system, it saves a lot of labor cost for the power plant.
d) Studies show that for every 1% increase in boiler efficiency, 2% of carbon dioxide emissions can be reduced , so the dry system also contributes to the reduction of emissions.
In conclusion, based on the study and analysis, the Unit 2 boiler efficiency of GN Power Mariveles Plant increased about 0.51% after retrofit to DUNOCON dry bottom ash handling system. The reduction of flue gas quantity is the main reason to improve the boiler efficiency. The advanced air control technology of the DUNOCON system is an important key point. “The recovery of radiant heat from the boiler throat and sensible heat from the bottom ash also improves the boiler efficiency. The improvement of boiler efficiency saves about 28,400 t of coal for the power plant every year. And compared with wet system, dry bottom ash handling system is more advanced, safe and stable, and saves a lot of operating costs for the power plant.”
Since the early 1990s, GNPower Ltd. Co. has been excelling in the power industry with their remarkable achievements in the completion of power projects. Their power plant projects had been providing electricity supply services to several Philippine-based customers. Other than developing coal-fired plant in Mariveles, (GNPower Mariveles Energy Center Ltd. Co.), they also have the GNPower Kauswagan Ltd. Co., and the upcoming GNPower Dinginin Ltd. Co. Of note, GNPower is the first Retail Electricity Supplier (RES) to be licensed by the Energy Regulatory Commission. They are also the first to have signed long-term power supply agreements with a group of Contestable Customers since 2006. GNPower also adheres to the mandate of the EPIRA Law of Department of Energy.
Mr Edgardo B. Cruz of Philippine Coal Plant Users Group and Mr Ariel Punzalan of PMR Group and GNPower Ltd. Co.
 Retrieved from the company website of GNPower Ltd. Co. - https://www.gnpower.com.ph/about-us-new/
 Chavez, Leilani (Nov. 5, 2020). Mongabay News. "Philippines declares no new coal plants — but lets approved projects through".
 Boado, Artemio, Cruz, Edgardo B., et. al. “A Study of the Changes in Efficiency of a Coal Fired Boiler Following the Conversion to a Dry Bottom Ash Handling System”.
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Abe Almirol - June 23, 2021
Cagayan River Rehabilitation: Initiatives from Ridge to Reef
After two severe weather disturbances that took place in the first half of November 2020 heavily hit eight regions in the Philippines, Pres. Rodrigo Duterte immediately signed Executive Order No. 120 creating the Task Force Build Back Better (TF-BBB) to initiate a comprehensive and integrated recovery. Cagayan and Marikina valleys suffered the heaviest damage and human casualties as floods and its aftermath landslides placed many parts of the country in a state of calamity for weeks. Typhoon Rolly (international name: Goni) made its landfall on 1 November 2020 and several days after its onslaught and in almost the same path, Typhoon Ulysses (international name: Vamco) carried with it heavy rains as it reached the Philippine shorelines on 11 November 2020. Tuguegarao and Marikina cities were in deep floods as Ulysses traversed the Philippine area of responsibility. The National Disaster Risk Reduction Management Council reported over 2.3 million people affected across eight regions in the country. Reports indicated that 23,089 individuals displaced were moved to evacuation centres while 46,987 individuals displaced stayed outside evacuation centres. The death toll from Ulysses has reached more than 70. It has severely damaged property and infrastructure in some areas. Videos circulating in social media showed floods reaching the roofs in some parts of Cagayan and Marikina City. Two agencies, the Department of Environment and Natural Resources (DENR) and the Department of Public Works and Highways (DPWH), were given the lead role in a task force working on an operational mode adopting the “whole-of-society approach”. All government agencies and instrumentalities were mandated by EO 120 to take part. After eight months of work, the TF-BBB has made significant gains in pursuing rehabilitation and post-recovery initiatives. DENR has realised that problems such as this needs to consider all factors affecting the whole watershed catchment basin where floods occur. Environmental advocates and experts often refer to this approach as the ridge-to-reef initiative. "In the months since we set out to work in November last year, we have now set into motion significant post-disaster recovery initiatives in three priority geographic areas involving the restoration of Cagayan, Marikina, and Bicol River basins," DENR Secretary and TF-BBB chair Roy A. Cimatu said. Cagayan River Dredging: Agencies in Action Cimatu and TF-BBB co-chairperson Secretary Mark A. Villar of the Department of Public Works and Highways (DPWH) led the ceremonial dredging of sandbars along Cagayan River’s constricted midstream and planting of Bamboo seedlings on the riverbank of Barangay Bangag in the town of Lal-lo, Cagayan last 2 February 2021. After removing the sandbar obstacles that impede water from flowing freely, the roots of planted Bamboos should serve as a soil binder to keep the riverbank intact in the future. There are three priority sandbars to remove near the Magapit bridge, measuring about 235 hectares with an estimated volume of seven million cubic meters, according to TF-BBB statements captured by the media. The first phase of DPWH dredging operations targeted this choke point which a past study identified as the cause of flooding in Tuguegarao City and other settlements near the riverbanks. TF-BBB in Region 2 is chaired by Regional Executive Director Gwendolyn Bambalan of the DENR and co-chaired by Regional Director Loreta Malaluan of the DPWH. In her message during one of the virtual sessions of the task force, Director Bambalan lauded the different government agencies for their support to the Build Back Better initiatives in the region. "The regional TF-BBB is not only addressing the protection and conservation of the environment but also the welfare of barangays and families affected by the restoration of the Cagayan River," Director Bambalan said. In that meeting, the DPWH discussed the dredging operation and riverbank protections works. The Department of Human Settlement and Urban Development gave an update on the status of resettlement projects while the Office of Civil Defence reviewed the improvement of systems and essential services. The Department of Trade and Industry also presented its accomplishments on livelihood projects. For its part, the Department of the Interior and Local Government presented its agenda for strengthened governance and mainstreaming of disaster-risk reduction and climate change action. Representatives of the Land Registration Authority also attended the meeting. The LRA will be the partner agency of the DENR for the easement recovery along the Cagayan River. The Technical Education and Skills Development Authority (TESDA) has trained residents who were eventually hired as laborers and equipment operators to help carry out the dredging operations. TF-BBB has also engaged the Department of Labour and Employment (DOLE) to provide employment assistance to 120 residents for the planting and nurturing of bamboo trees in Tuguegarao City and the towns of Alcala, Enrile, and Gattaran. This will be implemented through DOLE's "Tulong Panghanapbuhay sa Ating Disadvantaged/Displaced Workers" or TUPAD program. Magat Dam blamed In many reports published and echoed in mainstream media and social media, the opening of the Magat Dam floodgates was blamed as the cause of flooding. The National Irrigation Administration (NIA) came out with a fact check to clear its liability. Even the Senate initiated moved to investigate the matter. NIA’s acting department manager of Public Affairs and Information Office, Eden Victoria Selva, came up with a comprehensive technical response, explaining that the Magat river is just one of the many river systems draining to the Cagayan River. “It is noted that the carrying capacity of the Cagayan River is 25,400 m3/s while the maximum volume of water released from the Magat Dam is only 6,706 m3/s indicating that water discharge of Magat Dam due to Typhoon Ulysses is not the main cause of massive flooding in the provinces of Isabela and Cagayan,” Selva said in an article that appeared in INQUIRER.net on 10 June 2021. The controversial statements blaming the Magat Dam’s release of water also aroused public perception that points responsibility to the occupants of watershed areas in the upstream of Magat River. Those affected by the floods were quick to call for punitive actions against watershed occupants, including calls to ban mining in the province of Nueva Vizcaya, including those issued with legitimate permits to operate. Sharing the Burden of Watershed Restoration and Protection In the watersheds upstream of the Magat River, a 10-year project co-funded by the Republic of the Philippines and the Japan International Cooperation Agency is nearing completion. It is called the Forestland Management Project (FMP), a sequel of the several forestry sector projects implemented by the DENR’s Forest Management Bureau in the last 30 years. FMP is a holistic approach in Community Based Forest Management Agreement (CBFMA) areas in sub-watersheds in the upper areas of the Cagayan River, particular the provinces of Nueva Vizcaya, Ifugao and Quirino. FMP is also present in the Upper Pampanga River in Nueva Ecija and in Jalaur River in Iloilo. Anselmo Cabrera, an Institutional Development Specialist working at the Central Project Management Office of the FMP at the DENR Central Office, has proposed a cost sharing mechanism that Watershed Management Councils should develop for mainstreaming. He said there must be a system where every citizen or institution using water can pay for environmental services performed by duty-bearers protecting and maintaining watersheds. Through a cost sharing mechanism, communities living in critical watershed areas will be compensated for their efforts to ensure there is sufficient forest cover. With this scheme, upland farmers could minimize soil erosion by planting permanent crops instead of clearing spots to plant vegetables and other short-term cash crops. The FMP has so far initiated several hundred of hectares planted with coffee, Guyabano, Rambutan, and other fruit bearing trees. About 35 people’s organizations benefitting over 5,000 households, mostly from Kalanguya, Ibaloi, Isinai, Iwak and Ifugao indigenous cultural communities, LGUs were also called to take a more active role in watershed protection. Cabrera welcomes the favourable result of the Mandanas Ruling, where local governments won in getting their share in revenues collected outside the Bureau of Internal Revenue. The Supreme Court has ruled that LGUs can now get a share from the collection of the Bureau of Customs and other national revenues. Information available from the Department of Budget Management (DBM) revealed LGUs, which include provinces, municipalities, and barangays, could get as much as 37% increase in their internal revenue allotments from the national government in 2022. A DBM advisory directed LGUs to use these additional money to fund the full devolution of services, of which, integrated social forestry is one. Nueva Vizcaya Governor Carlos M. Padilla made a friendly overture when nasty comments were posted over social media by angry residents of Tuguegarao City who wallowed in deep floods for several days after Typhoon Ulysses. Some people accused people in Nueva Vizcaya of denuding the watersheds. Relief goods from Nueva Vizcaya were immediately sent in flood-stricken areas, a gesture that Cagayan Governor Manuel Mamba deeply appreciated publicly. He also called for collaboration between people downstream and upstream of the Cagayan River to understand and take actions together. During the last Watershed Management Council meeting, Gov. Padilla reiterated the importance of collaboration and networking to save watershed commons. He recalled a 2018 agreement with stakeholders which includes big water users such as SN Aboitiz and NIA, the two institutions managing the Magat hydropower and irrigation dam in Ramon, Isabela. Also included in the public pledge of support to the 2018 Nueva Vizcaya Declaration on Water are thousands of farmer’s organizations using water resources for irrigation and water utilities, like Solano Water and other entities providing services to majority of urban households. Watershed Management Councils were potent avenues for collaboration in watershed protection and maintenance. In Davao, a bulk water project implemented by Apo Agua Infrastructura, Inc. mentioned in a webinar that the Watershed Management Council has played a crucial role in mobilising communities and people. The TF-BBB in Cagayan Valley experience could be one of the best in the current administration’s whole-of-society approach in big projects. By mobilising both government agencies and communities, it has covered all areas of concern from the top of mountain ridges to the reefs in the sea. It would be exciting to measure if the impacts are indeed better ten years from now.
Philippine Resources - June 22, 2021
DENR studies possible lifting of ban on open-pit mining
The Department of Environment and Natural Resources (DENR) is still studying the possible lifting of the ban on open-pit mining, Malacañang said on Thursday. Presidential Spokesperson Harry Roque clarified that Executive Order No. 130, signed by President Rodrigo Duterte on April 14, does not include a lifting of the ban on open-pit mining. EO 130, which lifts the nine-year moratorium on mineral agreements, is to spur economic growth and support projects and programs of the government. “There is nothing in the executive issuance on mining which is EO No. 130 which lifts the ban on open-pit mining. I have conferred with [DENR] USec. Benny Antiporda and he says the matter is still being studied by the DENR,” Roque said in a Palace press briefing. He, however, reiterated that open-pit mining remains unacceptable for Duterte. In November 2017, Duterte said he agreed with the open-pit mining ban given the environmental damage it causes. Duterte, in his third State-of-the-Nation Address (SONA) on July 23, 2018, also warned the mining industry not to destroy the environment, saying environmental protection is one of his government’s priorities. “To the mining industry, I say this once again and maybe for the last time, do not destroy the environment or compromise our resources; repair what you have mismanaged,” Duterte said. Roque reiterated Duterte’s call to the mining industry to find other ways to extract minerals without destroying the environment. “But I understand from USec. Benny Antiporda that both the President and Secretary [Roy] Cimatu agreed that the mining industry must reinvent mining in a manner that would ensure that it is sustainable and would cost the least damage to the environment,” he added. Open-pit mining is allowed under Philippine law, but Duterte has rejected previous recommendations to lift the ban. The Philippines is the world’s biggest supplier of nickel ore and also among the top producers of copper and gold.
Philippine Resources - June 21, 2021
Villar: Estrella-Pantaleon Bridge On-Track for July 2021 Opening
Photo Credit: Department of Public Works and Highways Public Works and Highways Secretary Mark Villar reassured on Friday, June 18, 2021 that remaining civil works are being fast-tracked to open the new and modernized Estrella-Pantaelon Bridge by next month. “We are here on-site to show you that all substructure and superstructure of the Estrella-Pantaelon Bridge have been constructed and we are confident that we will be able to finish remaining works on approach road and ancillary/miscellaneous works by July 2021,” said Secretary Villar. Secretary Villar together with BCDA President & CEO and Presidential Adviser for Flagship Programs and Projects Secretary Vince Dizon, Transportation Secretary Arthur Tugade and DPWH Undersecretary for Unified Project Management Office (UPMO) Operations Emil K. Sadain inspected the substantially completed Estrella Pantaleon Bridge following an on-site Press Conference on Progress Update of Build, Build, Build Program. Citing a report from Undersecretary Sadain, Secretary Villar noted that the ongoing bridge project across Pasig River linking Estrella Street in Makati City and Barangka Drive in Mandaluyong City is now 93 percent complete. When completed, the new Estrella-Pantaleon Bridge widened from two (2) lanes to four (4) lanes is expected to accommodate as much as 50,000 cars daily, improving traffic situation in the area and decongesting the Epifanio delos Santos Avenue. The bridge-modernization project is implemented by the DPWH-UPMO Roads Management Cluster 1 (Bilateral) and is funded under a Chinese Grant together with Binondo-Intramuros Bridge. Article Courtesy of the Department of Public Works and Highways