Distributed Generation Mohammad Amin Latifi Bureau of Privatization Ministry of Energy

US electric industry as an example

Distributed Energy Systems Future Trends of Electric Utility Industry Central Power Plants Distributed Energy Systems Photovoltaic Array Microturbine Wind Turbine Fuel Cell Combustion Gas Turbines Energy Storage Devices

Operating System For DG  Distribution Substation Energy storage devices Micro-turbines Gas turbines Central Power Station Transmission line Smart controller Communication Regional Dispatch Energy Value Information Electric Power Monitoring & Control Lines Town Building Hospital Factory Remote location Stand-alone Distribution line  Source: Distributed Utility Associates

Definition Distributed Generation (DG) is the implementation of various power generating resources, near the site of need, either for reducing reliance on, or for feeding power directly into the grid. DG may also be used to increase transmission and distribution system reliability.

Technologies for DG Technologies for Distributed Energy Systems (DG) Gas technologies  Combustion gas turbines  Micro-turbines  Fuel cells Renewable Energy Technologies  Biomass power  Small wind turbines  Photovoltaic Arrays

Applications for DG Applications of DG Stand-alone Standby Grid-interconnected Peak shaving

Benefits of DG Benefits of DG Environmental-friendly and modular electric generation Increased reliability Fuel flexibility Uninterruptible service Cost savings On-site generation Standby Generation

Value of DG

Grid losses Vs. DG penetration level

Barriers of DG Barriers Technical Barriers  Protective equipment  Safety measures  Reliability and power-quality concerns Business-Practices Barriers  Contractual and procedural requirements for interconnection  Procedures for approving interconnection, application and interconnection fees,  Insurance requirements  Operational requirements Regulatory Barriers  Tariff structures applicable to customers  Net metering  Environmental permitting

What supports Technologies of DG? Power Electronics Technologies  Advanced Power Converter Design Technique  High-speed/high-power/low-losses power switches  New control techniques  Digital signal processors with high performance New communications in the form of the Internet Planning and valuation tools  Value to grid  Capacity needs assessment

Combustion Gas Turbine Comparison of Several Technologies Technology Combustion Gas Turbine Micro-turbine Fuel Cell Wind Turbine Photovoltaic Array Size 0.5 – 30+MW 25 – 500 kW 1 kW – 10 MW 0.3 kW – +5 MW 0.3 kW -2 MW Installed Cost ($/kW) 400 – 1,200 1,200 – 1,700 1,000 – 5,000 1,000 - 5,000 6,000 – 10,000 O&M Cost ($/kWh) 0.003 – 0.008 0.005 – 0.016 0.0019 – 0.0153 0.005 0.001-0.004 Elec. Efficiency 20 - 45% 20 – 30% 30 – 60% 20 – 40% 5 – 15% Overall Efficiency 80 – 90% 80 – 85% Fuel Type natural gas, biogas, propane natural gas, hydrogen, biogas, propane, diesel hydrogen, natural gas, propane wind sunlight  Source: Distributed Energy Resources and Resource Dynamics Corporation

Combustion Gas Turbines (1) fuel air Power Turbine Combustor Compressor Generator Power Converter HRSG (Heat Recovery Steam Generator) Feed water Process steam Fig. 1 Block diagram of Combustion Gas Turbine System.

Combustion Gas Turbines (2) Features Very mature technology Size: 0.5 – 30+ MW Efficiency: electricity (20 – 45%), cogeneration (80 – 90%) Installed cost ($/kW): 400 – 1,200 O&M cost ($/kWh): 0.003 – 0.008 Fuel: natural gas, biogas, propane Emission: approximately 150 – 300 ppm NOx (uncontrolled) below approximately 6 ppm NOx (controlled) Cogeneration: yes (steam) Commercial Status: widely available Three main components: compressor, combustor, turbine Start-up time range: 2 – 5 minutes Natural gas pressure range: 160 – 610 psig Nominal operating temperature: 59 F

Combustion Gas Turbines (3) Advantages & Disadvantages Advantages  High efficiency and low cost (particularly in large systems)  Readily available over a wide range of power output  Marketing and customer serving channels are well established  High power-to-weight ratio  Proven reliability and availability Disadvantages  Reduced efficiencies at part load  Sensitivity to ambient conditions (temperature, altitude)  Small system cost and efficiency not as good as larger systems

Micro-turbines (1)

Micro-turbines (2) Features Size: 25 – 500 kW Efficiency: unrecuperated (15%), recuperated (20 – 30%), with heat recovery (up to 85%) Installed cost ($/kW): 1,200 – 1,700 O&M cost ($/kWh): 0.005 – 0.016 Fuel: natural gas, hydrogen, biogas, propane, diesel Emission: below approximately 9 - 50 ppm NOx Cogeneration: yes (50 – 80C water) Commercial Status: small volume production, commercial prototypes now Rotating speed: 90,000 – 120,000 Maintenance interval: 5,000 – 8,000 hrs

Micro-turbines (3) Advantages & Disadvantages Advantages Disadvantages  Small number of moving parts  Compact size  Light-weight  Good efficiencies in cogeneration  Low emissions  Can utilize waste fuels  Long maintenance intervals Disadvantages  Low fuel to electricity efficiencies

Fuel Cells (1)  Electrochemical energy conversion: Hydrogen + Oxygen  Electricity, Water, and Heat Power Converter Reformer Fuel H2 O2 from air Anode Catalyst Cathode Polymer Electrolyte +  H2O Exhaust AC Power Fig. 3 Block diagram of Fuel Cell System. 18

Fuel Cells (3) Features (2) Size: 1 kW – 10 MW Efficiency: electricity (30 – 60%), cogeneration (80 – 90%) Installed cost ($/kW): 1,000 – 5,000 O&M cost ($/kWh): 0.0019 – 0.0153 Fuel: natural gas, hydrogen, propane, diesel Emission: very low Cogeneration: yes (hot water) Commercial Status:  PAFC: commercially available  SOFC, MCFC, PEMFC: available in 2004

Wind Turbines (1) Fig. 4 Block diagram of Small Wind Turbine System. Gear Box Generator Low-speed shaft High-speed Wind Power Converter Nacelle Fig. 4 Block diagram of Small Wind Turbine System.

Wind Turbines (2) Features Size: small (0.3 - 50 kW), large (300 kW – +5 MW) Efficiency: 20 – 40% Installed cost ($/kW): large-scale (900 - 1,100), small-scale (2,500 - 5,000) O&M cost ($/kWh): 0.005 Fuel: wind Emission: zero Other features: various types and sizes Commercial Status: widely available Wind speed:  Large turbine: 6 m/s (13 mph) at average sites  Small turbine: 4 m/s (9 mph) at average sites Typical life of a wind turbine: 20 years

Wind Turbines (3) Advantages & Disadvantages Advantages Disadvantages  Power generated from wind farms can be inexpensive  Low cost energy  No harmful emissions  Minimal land use : the land below each turbine can be used for animal grazing or farming  No fuel required Disadvantages  Variable power output due to the fluctuation in wind speed  Location limited  Visual impact : Aesthetic problem of placing them in higher population density areas  Bird mortality

Photovoltaic Arrays (1) PV module Cell Array Charge Controller AC power DC power Power Converter Batteries Fig. 5 Block diagram of Photovoltaic Array System.

Photovoltaic Arrays (4) Features (3) Size: 0.3 kW – 2 MW Efficiency: 5 – 15% Installed cost ($/kW): 6,000 – 10,000 O&M cost ($/kWh): 0.001 Fuel: sunlight Emission: zero Main components: batteries, battery chargers, a backup generator, a controller Other features: no moving parts, quiet operation, little maintenance Commercial Status: commercially deployed An individual photovoltaic cell: 1 – 2 watts

Photovoltaic Arrays (5) Advantages & Disadvantages Advantages  Work well for remote locations  Require very little maintenance  Environmentally friendly (No emissions) Disadvantages  Local weather patterns and sun conditions directly affect the potential of photovoltaic system. Some locations will not be able to use solar power

Energy Storage Technologies Batteries Capacitors Flywheels Superconducting Magnetic Energy Storage Compressed air energy storage

Different Configurations for DG 1. A Power Converter connected in a Stand-alone AC System (1) Distributed Energy System Power Converter Vdc Loads DSP Controller Sensors V, I, P, Q 3  AC 240/480 V 50 or 60 Hz Trans. Fig. 6 Block diagram of a Power Converter connected in a stand-alone AC system.

Different Configurations for DG 1. A Power Converter connected in a Stand-alone AC System (2) I Vdc V E Load 3  AC 240/480 V 50 or 60 Hz Fig. 7 Simplified block diagram of Fig. 6.

Different Configurations for DG 2. A Power Converter connected in Parallel with the Utility Mains (1) Distributed Energy System Power Converter Vdc Utility Mains 3  AC 240/480 V 50 or 60 Hz DSP Controller Sensors V, I, P, Q Trans. Loads Fig. 8 Block diagram of a Power Converter connected in parallel with the utility mains.

Different Configurations for DG 2. A Power Converter connected in Parallel with the Utility Mains (2) Utility Mains I Vdc V E 3  AC 240/480 V 50 or 60 Hz Fig. 9 Simplified block diagram of Fig. 8.

Different Configurations for DG 3. Paralleled-Connected Power Converters in a Stand-alone AC System (1) Power Converters Micro-turbine Fuel Cell Loads DSP Controller V, I, P, Q Sensors 3  AC 240/480 V 50 or 60 Hz Trans. Fig. 10 Block diagram of Paralleled-Connected Power Converters in a Stand-alone AC System.

Different Configurations for DG 3. Paralleled-Connected Power Converters in a Stand-alone AC System (2) Vdc1 I1 V E I2 Vdc2 Loads Fig. 11 Simplified block diagram of Fig. 10.

Different Configurations for DG 4. Paralleled-Connected Power Converters with a common DC grid in a Stand-alone AC System (1) Power Converters Micro-turbine Loads DSP Controller 3  AC 240/480 V 50 or 60 Hz V, I, P, Q Sensors DC Grid Fuel Cell Fig. 12 Block diagram of Paralleled-Connected Power Converters with a common DC grid in a Stand-alone AC System.

Different Configurations for DG 4. Paralleled-Connected Power Converters with a common DC grid in a Stand-alone AC System (2) I1 Vdc E I2 DC Grid Loads 3  AC 240/480 V 50 or 60 Hz Fig. 13 Simplified block diagram of Fig. 12.

Schematics of an average European electricity grid and connection levels for DG and RES

DG Network Connection Issues Impact on power system operation (changing power flows, voltage profile, uncertainty in power production and etc) Voltage regulation Power losses Power quality (Sags, swells and etc ) Harmonics Short circuit levels Location and size of DG Safety and protection consideration

Voltage regulation example

Data needed to evaluate the DG impact Size rating of the proposed DR Type of DR power converter (static or rotating machine) Type of DR prime energy source (such photovoltaic, wind or fuel cell Operating cycles Fault current contribution of DR Harmonics output content of DR DR power factor under various operating conditions Location of DR on the distribution systems Locations and setting of voltage regulation equipment on distribution system Locations and settings of equipment for over current protection on distribution system

Main Barriers to DG

RES Historical Development

Distributed Generation (DG) Share of Total Generation Capacity (2007)

What is CHP? Integrated System Provides a Portion of the Electrical Load Utilizes the Thermal Energy Cooling Heating

Overview of CHP Technologies Technology Pros Cons Fuel Cell - Very low emission - Exempt from air and permitting in some areas - Comes in a complete “ready to connect” package High initial investment Limited number of commercially available units Gas Turbine Excellent service contracts Steam generation capabilities Mature technology Requires air permit The size and shape of generator package is relatively large Micro-turbine Lower initial investment High redundancy Low maintenance cost Relative small size and installation flexibility Relatively new technology Synchronization problems possible for large installations Recip. Engine Low initial investment Relatively small size High maintenance costs Low redundancy

Benefits of CHP High Efficiency, On-Site Generation Means Improved Reliability Lower Energy Costs Lower Emissions (including CO2) Conserve Natural Resources Support Grid Infrastructure Fewer T&D Constraints Defer Costly Grid Upgrades Price Stability Facilitates Deployment of New Clean Energy Technologies

Factors for CHP Suitability High Thermal Loads-(Cooling, Heating) Cost of buying electric power from the grid versus to cost of natural gas (Spark Spread) Long operating hours (> 3000 hr/yr) Need for high power quality and reliability Large size building/facility Access to Fuels (Natural Gas or Byproducts)

Generators Two Types of Generators Induction • Requires Grid Power Source to Operate • When Grid Goes Down, CHP System Goes Down • Less Complicated & Less Costly to Interconnect • Preferred by Utilities Synchronous • Self Excited (Does Not Need Grid to Operate) • CHP System can Continue to Operate thru Grid Outages • More Complicated & Costly to Interconnect (Safety) • Preferred by Customers

Efficiency Benefits of CHP

Environmental Benefits of CHP (NOx)

CO2 Emissions Reductions from CHP Power Plant 6.0 MWe 70,000 pph Steam Boiler 117 Boiler Fuel (Gas) Lb/MMBtu CO2 Emissions 56k Tons/yr 43k Tons/yr …TOTAL ANNUAL CO2 EMISSIONS… 95k Tons 56k Tons 52k Tons/yr Conventional Generation Combined Heat & Power: Taurus 65 Gas Turbine Efficiency: 31% Efficiency: 80% Efficiency: 82.5% Power Station Fuel (U.S. Fossil Mix) 186 lb/MMBtu 117 CHP Fuel (Gas) Lb/MMBtu 39,000 Tons CO2 Saved/Year

CHP and Energy Assurance Combined Heat & Power (CHP) can Keep Critical Facilities Up & Operating During Outages For Example, CHP can Restore Power and Avoid: – Loss of lights & critical air handling – Failure of water supply – Closure of healthcare facilities – Closure of key businesses

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