Development of the First Combined Heat and Power plant in the Caribbean (CHP District Energy) Presented in the DistribuGen Conference & Trade Show for Cogeneration/CHP 2015 April 7-9, 2015 Houston, Texas This paper will be presented by: Alfredo Colombano from Colombs Energy, Bruce K. Colburn and Martin T. Anderson from EPS Capital Corp. Colombs Energy 1
CEPM CEPM s Overview Facts CONSORCIO ENERGETICO PUNTA CANA MACAO (CEPM), Is a privately owned utility company engaged in generating, transmitting, and distributing electricity through two isolated integrated power systems serving the fast growing tourism-based Punta Cana-Bávaro and Bayahibe regions in the Dominican Republic. Serves 60 hotels with approximately 35,000 rooms in these tourist destinations as well as approximately 17,000 commercial and residential customers. Company s installed capacity is 90 MWe with Wartsila and Hyundai diesel engines operated using HFO. CEPM also supplies thermal energies (5,000 TR chilled water, hot water and steam), with sales of: 700 GWhe/year of electric energy, 44 GWhcw/year of chilled water, 22 GWhdhw/year of domestic hot water. 2
District energy systems produce steam, hot water or chilled water at a central plant. The steam, hot water or chilled water is then piped underground to individual buildings for space heating, domestic hot water heating and air conditioning. As a result, individual buildings served by a district energy system don't need their own boilers or furnaces, chillers or air conditioners. The district energy system does that work for them, providing valuable benefits including: Improved energy efficiency Enhanced environmental protection Fuel flexibility Ease of operation and maintenance Reliability Comfort and convenience for customers Decreased life-cycle costs Decreased building capital costs Improved architectural design flexibility What is a District Energy? 3
Energy - Efficiency Comparisons From: International District Energy Association (IDEA) From: International District Energy Association (IDEA) 4
Chilled Water production with Electric Chiller (Without Cogeneration) 10 MWe (40%) 8 MWe Fuel Oil Energy HFO 25 MW (100%) 2 MWe 5 MWcw (1,421 RT) Chiller with electric compressor COP 2.5 5
Chilled Water Production with Absorption Chiller (With Cogeneration) 8 MWe (40%) Fuel Oil Energy HFO 20 MW (100%) 20% of reduction 7 MWth (35%) 5 MWcw 1,421 RT) Absorption Chiiler COP 0.71 6
CEPM s CHP-District Energy Project Overview As part of the expansion of CEPM s services to an Energy Services Company (ESCO), our team developed the First CHP-District Energy system in the Caribbean. This system provides 5,000 TR of chilled water (using Absorption Chillers) and Domestic Hot Water (DHW) to Hotels located near to CEPM s power plant. Waste heat comes from the exhaust gases and cooling water (Jacket water, Oil Cooler, Intercooler) of Wartsila Diesel Engines 18V32 Vasa (6 MWe each) that consume Heavy Fuel Oil (HFO). The distance from the power plant and the different Hotels is about 2.5 miles (4 kilometers), making the new hot water loop a viable installation process. 7
CEPM s CHP-District Energy Project Overview (cont.) Cooling is provided by locally based absorption chillers and the heat exchanger used to produce DHW (Domestic Hot Water) for both cooling and domestic hot water were installed inside the hotels. The HTHW (High Temperature Hot Water) is produced in the power plant with a temperature of roughly 248ºF (120ºC). At the hotel this HTHW supplies the thermal energy to drive single stage absorption chiller units. The HTHW output after being used to provide chilled water via the absorption chillers is then connected to an additional set of heat exchangers to produce DHW, and the spent HTHW loop temp water is then sent back to the power plant with a temperature of +/- 158ºF (70ºC). 8
CEPM s CHP-District Energy Project Overview (cont.) In this way a large delta T 90ºF (50ºC) can be effected by using the single loop to serve two purposes, first high quality heat to run the absorbers, and second the lower temperature resulting water out of the chillers used for all or part of domestic hot water generation. The key goal and advantage of this project is to recover waste heat from the operation of the existing diesel engines with an electric efficiency of 39.5%, and produce thermal energy which used to be wasted away and instead reuse part of it from the exhaust gases to create new economic value. Only about 16% of the heat is recoverable due to limitations imposed by the dew point of the exhaust gases when HFO with 2.5 % Sulfur is used, about 25.2 % on the cooling water which is only recoverable to the level of about 9.1%, and the remainder is low temperature water used via cooling water to dump heat, with roughly an additional 3% by radiation to the surrounding area. 9
CEPM s CHP-District Energy Project Overview (cont.) The sole reason the power company would consider this type of additional new investment is that their system MWe load has been growing about 5% per year, so redeploying some electrical load into thermal does not really hurt their business economically, and the lower resulting lower utility costs to the resort hotels provides an economic incentive to those resorts to continue dealing with the utility, which otherwise the resorts would not have to. All is economically done that benefits both the utility and the large resorts, to say nothing of helping control costs to the other local customers (more and more local businesses and homes are connecting to this grid, some having had their own small generator systems, or connected to an adjacent power source). 10
CEPM s CHP-District Energy Project Overview (cont.) The overall approach utilized as a business case was to take over the operation and maintenance responsibility at the resorts for the chiller plants, including compressors, chilled water pumps, condenser water pumps, and cooling towers, as needed, and install new absorption chiller systems, and thermal heat recovery systems, so that in the end chilled water, and domestic hot water heat are being sold. The heating system was similar in that the existing boilers and pumps were taken over by the utility, so that burden was removed from the resorts. The actual system results are sold as thermal KWH to the owners. 11
CEPM s CHP-District Energy Project Overview (cont.) The existing electric chillers are still used in summer peaking via electronic remote dispatch since there is insufficient heat through the loop for such peaks, but again, it is not relevant to the owner anymore since they buy delivered results. The paper will present the overall issues, and provide an overview of the results from this implementation process. It involved a few years of planning and budgeting, and securing written long term agreements from enough resorts to get the project rolling, with the rest presumed to come aboard as new loads once they could see the facility in long term operation, as has occurred in other district heating projects in Europe and the USA. The project was completed in 30 months and has been in operation now for 2 years. 12
CHP-District Energy Building Blocks Diesel Engine or Heat Source Waste Heat Recovery Systems Waste Heat Transmission & Distribution Circuit Chilled Water Plant End Users (Hotels) Heat balance Waste Heat Quality (Combustion Gases & Cooling Water Temperatures) Type of Fuel WHRU Gas & Water side Corrosion Issues Combustion Gases Dew point Load and Temperature Control Water/Water Heat Exchanger High Temperature Hot Water Vs Steam Maximum pressures & Temperatures Circuit Pressurization Differential Temperature (Supply and Return) Variable Vs Constant Flow Electric Energy for Water Pumping Water Hammer & Pressure Surge Water Chemical Treatment Single Stage Vs Double Stage Absorption Chiller Electric Motor Driven Compressor Chiller Adsorption Chiller (future) Thermal Load Hourly Profile Electric Load Hourly Profile Thermal Base load Vs Peak Load Thermal Energy Storage? Thermal energy Billing meter 13
Diesel Engine or Heat Source Schematic of CEPM CHP-District Energy (Cooling/DHW ) Waste Heat Recovery System Waste Heat Transmission & Distribution Circuit Chilled Water Plant End Users (Hotels) Wartsila HT Cooling System 195.8ºF (91ºC) 122 ºF (50ºC) LT Cooling System E - 1 EX3 EX2 HT Cooling System LT Cooling System 248 ºF (120 ºC) Main Feeder Pumps Expansion Tank 158 ºF (70 ºC) Condenser Water Cooling Systems (Cooling Tower TowerTech) COP = 0.70 Absorption Chiller (Broad) 176 ºF (80 ºC) EX4 Chilled Water Systems Domestic Hot Water DHW 140 ºF (60 ºC) Chilled Water (CW) Electric Driven Chiller Water Cooled 44.6 ºF (7 ºC) Electric Driven Chiller Air Cooled 14
Project Main Activities Data Collection and Analysis Impact over the CEPM Electric Load Economic Power Generation Dispatch Available Waste Heat from CEPM Power Generators Load Characterization and Modeling Optimization Chiller Plants Design High Temp. Hot Water System Design Waste Heat Recovery System Design DHW Plants Design CAPEX and Cost of Service for Thermal Energies Tariff Negotiation with Hotels 15
Diesel Engine Energy Balance (HFO) Diesel Engine or Heat Source Notes: (*) Depend on the configuration of charge air coolers (One-stage or two-stage charge air cooler (**) Depend on the outlet temperature of exhaust gases from waste heat recovery boiler, limited by the Dew Point of the combustion gases (Sulfur %) Electric Energy 6,000 kwe (39.5%) 6,000 kwe (39.5%) Fuel Input HFO 15,190 kw (100%) Exhaust Gases 4,860 kw (32%) Cooling Water 3,832 kw (25.2%) Exhaust Gases Waste Heat Non Recoverable 2,430 kw (16%) 350 C/ 662 F) Exhaust Gases Waste Heat Recoverable 2,430 kw (16%) (**) 350 C/ 662 F) High Temperature Cooling Water 1,382 kw (9.1%) (*) (91 C/ 195F) Low Temperature Cooling Water 2,450 kw (16.1%) (*) (50C/122F) 3,812 kw (25.2%) Radiation 455.7 kw (3.0%) 9,812 kw (64.7%) 16
Diesel Engine Energy Balance (NG) Diesel Engine or Heat Source Notes: (*) Depend on the configuration of charge air coolers (One-stage or two-stage charge air cooler) Electric Energy 000 kwe (39.5%) 6,000 kwe (39.5%) Fuel Input NG 15,190 kw (100%) Exhaust Gases 4,860 kw (32%) Exhaust Gases Waste Heat Non Recoverable 1,530 kw (10%) 350 C/ 662 F) Exhaust Gases Waste Heat Recoverable 3,330 kw (21.9%) (**) 350 C/ 662 F) 4,712 kw (31.0%) Cooling Water 3,832 kw (25.2%) High Temperature Cooling Water 1,382 kw (9.1%) (*) (91 C/ 195F) Low Temperature Cooling Water 2,450 kw (16.1%) (*) (50C/122F) Radiation 455.7 kw (3.0%) 10,712 kw (70.5%) 17
Waste Heat Recovery System Waste Heat Recovery System 6,000 kwe (39.4%) Fuel Oil Energy HFO 15,190 kw (100%) Exhaust Gases 662ºF (350ºC) HEX3 WHRU 329ºF (165ºC) 2,430 kwth (16%) 195.8ºF (91ºC) 248ºF (120ºC) HEX 2 1,382 kwth (9%) 3,812 kwth (25%) Diesel engine Wartsila 18V32 Vasa HFO 170.6ºF (77ºC) All figures are indicative 18
Temperature ºF Waste Heat Recovery Systems Temperature Profile 700 662.0 HFO # 6 100 % 650 Waste Heat Recovery System 600 550 500 450 400 350 300 250 200 150 100 296.5 248.0 331.0 250.0 195.8 194.5 194.5 This temperature is limited by the Flue Gases Dew Point temperature This temperature is limited by the minimum metal temperature in the tube HT Cooling Water 187.6 170.6 50 0 WHRU Hot end WHRU Cold end HEX2 Hot end HEX2 Cold end Exhaust Gases Temperature High Temp. Hot water Temperature WHRU Water Temperature HT Circuit Temperature to HEX2 19
Minimum Design Tube Metal Temperature Waste Heat Recovery System To avoid corrosion of the tubes, we must limit the outlet temperature of the exhaust gases recovery unit so that the temperature in the metal tube is not below the dew point exhaust gases, for example a sulfur content of 2.5% the curve indicates 93.3 C (200 F), while more will lower the temperature of the exhaust gases more heat is recovered but is limited by the dew point. 20
Minimum Design Tube Metal Temperature Waste Heat Recovery System Other literature indicates conservative values of the design temperature of tube metal. In this case to a sulfur content of 2.5% the curve indicates about 121.1 C (250 F), this fuel which take the value to adjust the water inlet temperature to the recovery unit, the temperature of the surface of the tube exposed to the exhaust gases tends to this value. HFO From: Steam 41th Edition The Babcock & Wilcox Company 21
Business Model Option 1 Produce High Temperature Hot Water (HTHW) 248 ºF (120ºC) Produce Chilled Water (CW) in power plant at CEPM 44.6 ºF (7ºC) 5,000 TR Distribute Chilled Water (CW) to the hotels Waste Heat Transmission & Distribution Circuit This option seems more expensive, because the temperature differential is only 9ºF (5ºC), which implies a large flow circulating (13,333 GPM) in the distribution net work and therefore larger pipe diameters (Diameters 24 to 30 inches) COP = 0.70 High Temperature Hot Water (HTHW) 248-176ºF (120-80ºC) 25,121 kwte 2,381 GPM Delta T = 72ºF (40ºC) Chilled Water 44.6-53.6ºF (7-12ºC) 5,000 TR 17,585 kwr 13,333 GPM Delta T = 9ºF (5ºC) 22
Business Model Option 2 Produce High Temperature Hot Water (HTHW) 248ºF (120ºC) Distribute High Temperature Hot Water 248ºF (120ºC) Produce Chilled Water (CW) 44.6ºF (7ºC) in each hotel 5,000 TR Produce Domestic Hot Water (DHW) 140 ºF (60ºC) in each hotel This option seems less expensive, because the temperature differential is 72ºF (40ºC), which implies a small flow circulating (2,198 GPM) in the distribution net work and smaller pipe diameters (Diameters 14 to 16 inches) COP = 0.70 COP = 0.70 Waste Heat Transmission & Distribution Circuit High Temperature Hot Water (HTHW) 248-158ºF (120-70ºC) 31,402 kwte (include 6,280 kwte for DHW) 2,381 GPM Delta T = 90ºF (50ºC) COP = 0.70 This option also allows to supply Domestic Hot Water to the hotels Chilled Water 44.6-53.6ºF (7-12ºC) 23
High Temperature Hot Water (HTHW) System Vs Steam System: Advantages of HTHW over steam heat distribution systems: Waste Heat Transmission & Distribution Circuit The amount of blow down required by a boiler depends on the amount and nature of the makeup water supplied. HTHW systems have closed circuits, require little makeup, therefore, practically never require blow down whereas steam systems commonly lose about 1% to 3 percent of the total boiler output because frequent blow downs are required. Operation within closed circuits permits reducing the size of water treating systems to a minimum Due to the heat storage capacity of HTHW systems (large mass of water), short peak loads may be absorbed from the accumulated heat in the system. The closed recirculation system reduces transmission and thermal losses to a minimum while practically eliminating corrosion and scaling of generators, heat transfer equipment, and piping. Both supply and return high temperature water piping can be run up or down and at various levels to suit the physical conditions of structures and contours of the ground between buildings without the problems of trapping and pumping condensate 24
Electric Motor Driven Centrifugal Compressor Chiller Energy Balance Chilled Water Plant COP = 3 W Electric Energy 333 kwe Electric Motor Driven Centrifugal Compressor Chiller Q C Chilled Water 1,000 kw (284 TR) (44.6ºF/7ºC) Coefficient Of Performance (COP) Cooling Water 1,333 kw Where Q C is the heat removed from the cold reservoir. W is the work or heat consumed by the heat pump. 25
Single-Stage Hot Water Absorption Chiller Energy Balance Chilled Water Plant COP = 0.7 Electric Energy 5 kwe W High Temperature Hot Water 1,428 kw (248ºF/120ºC) (Minimum 208ºF/98ºC) Single-Stage Hot Water Absorption Chiller Q C Chilled Water 1,000 kw (284 TR) (44.6ºF/7ºC) Cooling Water 2,433 kw Coefficient Of Performance (COP) Where Q C is the heat removed from the cold reservoir. W is the work or heat consumed by the heat pump. 26
Double-Stage Hot Water Absorption Chiller Energy Balance Chilled Water Plant COP = 1.4 Electric Energy 10 kwe W High Temperature Source 714 kw (356ºF/180ºC) Double-Stage Hot Water Absorption Chiller Q C Chilled Water 1,000 kw (284 TR) (44.6ºF/7ºC) Cooling Water 1,724 kw Coefficient Of Performance (COP) Where Q C is the heat removed from the cold reservoir. W is the work or heat consumed by the heat pump. 27
CDD (ºF) Cooling Monthly Profile End Users (Hotels) The cooling load is highly correlated with the Cooling Degree Day CDD and in a hotel is also influenced by the room occupancy 900 800 700 600 500 400 300 200 100 Punta Cana Cooling Degree Day CDD 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 28
0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Load kw Cooling Load Vs. DHW Load Hourly Profile End Users (Hotels) As shown there are two peaks in demand for DHW (red line) one at 8:00 and one at 18:00, these peaks do not coincide with the peak cooling demand therefore HTHW demand that drives the absorption chiller; in order to exploit the maximum of the thermal energy from HTHW circuit that leaves the absorption chillers to heat the DHW, tanks are used to store thermal energy during off peak hours. 1,600 1,400 1,200 Typical Hotel CW and DHW Load Profile 1,000 800 600 400 200 - Day's Hours CW Load (kw) DHW Load (kw) HTHW for Abs Chiller 29
The results of this project to date can summarize as follows: Reduction of 25% of the electrical energy (kwh) consumed by the resorts versus the option of not cogeneration, this is because about these resort group consumed 34% of the electrical bill to produce chilled water before the district project energy was implemented. This implies that the utility consume 25% less fuel to supply electric power to these resort group and can delay the expansion of electrical transmission and distribution networks. The base demand for chilled water of the resorts was covered by the new absorption chillers plus reuse of limited amount of existing peak cooling with the current older electric chillers. All demand for domestic hot water was supplied to the resorts group by the district energy, therefore the fuel consumption in the domestic hot water boilers was reduced to zero. This is meaningful given that all were operated from Diesel or GLP, which is very expensive. 30
The results of this project to date can summarize as follows: The overall COP of the systems with pumps, fans, compressors before was about 2.7, and the overall system after around COP=15 in winter, and about 7 or so for 365 days (due to the reuse of the older electric chillers for peaking purposes). The business case required that the resort owners sign long term contracts to insure the new cogen system loop and appurtenance s could be appropriately amortized.. This project demonstrated that you can use waste energy to produce thermal energies (chilled water and domestic hot water) required in the resorts for the comfort of its customers, in such a way that both the resorts benefit through total cost reduction as compared to the previous all electric load case, and the utility wins through actually increasing net revenues in a cost effective way which helps to cement a long term relationship with large key customers. This then becomes truly a win-win situation for all, which is one of the avowed goals of any third party cogeneration project. 31
Fuel Oil and Greenhouse Gas Emissions Reduction With this cogeneration approach, about 25% of thermal energy is recovered to drive absorption chillers and DWH heat exchangers and reduce the Fuel consumption by 35,740 Bbl/year of HFO and 32,881 Bbl/year of LPG. The Greenhouse gas emission is reduced by over 28,872 metric tons CO2/year. Greenhouse Gas emission reduction effects Chilled Water Production Absorption Chillers TR 5,000 Electric Chillers Displaced TR 5,000 Electric Chillers Displaced kwcw 17,585 Coefficient Of Performance (weighted) COP 6.0 Electric Power for Chillers Displaced kwe 2,931 Load Factor 0.95 Electric Energy for Chillers Displaced MWhe/year 24,390 GHG emission factor for HFO Power Generation tco2/mwhe 0.8084 Avoided CO2 emissions tco2/year 19,716 Avoided Fuel Oil (HFO) Bbl/year 35,740 Domestic Hot Water Production Domestic Hot Water Production displaced from boiler kwdhw 6,280 Load Factor 0.50 Domestic Hot Water Production displaced from boiler MWhdhw/year 27,506 GHG emission factor for LPG tco2/mwhdhw 0.3329 Avoided CO2 emissions tco2/year 9,158 Avoided Fuel (LPG) Bbl/year 32,881 Total Avoided CO2 emissions tco2/year 28,874 32
Questions? Alfredo Colombano BSIE, MBA, CEM, DGCP, REP Engineering Director Colombs Energy +1 281 686 2083 alfredo.colombano@colombsenergy.com alfredo.colombano@usa.net Bruce K. Colburn PhD., P.E., CEM, DGCP Project Energy Efficiency Engineer EPS Capital Corp. +1-610-525-4438 bcolburn@epscapital.com Martin T. Anderson Energy Efficiency Engineering Manager EPS Capital Corp. +1-610-368-3703 manderson@epscapital.com 33