technical paper - redhawk energy

Technical PaperPower Choices for Remote Site Prime &

Backup Power Applications

RedHawk Energy Systems, LLC 10340 Palmer Rd., S.W.

Pataskala, OH 43062

ph: 740-964-4000 www.redhawkenergy.net

Purpose: There are several choices of technologies available related to power systems for remote site prime and backup applications. This paper is focused on those power systems that are appropriate for applications in the range of 5 to 6000 watts.

Choices:Among the available choices for locally generating electrical power (AC and/or DC) when a utility connection is not available and/or too expensive:

While all of these choices can work in a given application, the most appropriate choice requires an analysis of the specific application needs, the local environmental conditions, and the operating conditions (including desired maintenance intervals) involved.

Photovoltaic (Solar) Power SystemsReliable, proven source of DC power by converting sunlight directly into electricity.

Wind Turbines Durable source of DC power by capturing the energy of moving air and converting it into electricity.

Fuel Cells Solid state DC generator that converts chemical energy into electricity.

Thermoelectric Generators (TEGs) Reliable source of DC power by converting heat directly into electricity.

Stirling Engines Closed-cycle external combustion engine that efficiently transforms a variety of fuels and other heat sources into electricity.

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Copyright © 2017 All Rights Reserved RedHawk Energy Systems, LLC

Power Choices for Remote Site Prime & Backup Power Applications

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Photovoltaic (Solar) Power Systems

Application Considerations:

PV Advantages:

PV Disadvantages:

PV (solar) power systems provide a reliable, proven source of DC power by converting sunlight directly into electricity. PV modules require very little maintenance with the occasional cleaning of modules, check of electri-cal connections, check of system regulators and check of battery storage systems. PV systems operate on “sunlight” and therefore don’t incur any ongoing fuel costs or requirements. Most PV modules are designed and rated to provide reliable performance and life for 20+ years. Nominal PV module voltages of 12 and 24 volts can be scaled in a series and/or parallel configu-rations to accommodate and extended range of system operating voltages and power ratings. Because PV modules are DC power sources, the use of inverters and/or converters can be used to provide mult-voltage DC or AC output.

PV systems are intermittent generators of power. Loads requiring power at times other than when the sun is shining require an energy storage system (batteries). Batteries (pictured right) provide an energy storage buffer and are used to accommodate loads that need to be powered through the night and over extended periods of inclement weather. Proper mounting structures are required to hold the individual PV modules in a system, allow integrated sys-tem wiring, and enable proper alignment and module tilt to optimize energy capture. PV systems are effective in most places with unobstructed access to sunlight. Specific location factors will impact the structure design and should be taken into consideration such as: wind loading, expandability, maintenance, and exposure to theft/vandalism.

“PV systems are effective in most places with unobstructed

access to sunlight”

• Proven Source of DC Power

• No Waste Byproducts/Emissions

• No Ongoing Fuel Costs

• Require Direct Exposure to Sunlight

• Larger Footprint Compared to Other Power Solutions Due to Panel Inefficiencies

• Shading From Trees, Hills & Mountains Can Cause Issues

• Susceptible to Vandalism & Theft

• Subject to Seasonal Variations

• Low Maintenance

• “Green” Energy Producer

• 20+ Years Life (Panels)

Solar (PV)

RedHawk Energy Solar Power System (pictured)

RedHawk Energy Battery Box (pictured)


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Wind Turbines


Wind Turbine Advantages:

Wind Turbine Disadvantages:

Wind Turbines capture the energy of moving air and convert it into electricity. A wind turbine typically consists of a rotor, electric generator, and a control system. The rotor, which looks much like an airplane propellor in most cases, is turned by the wind. The rotor is connected to a shaft which either directly or through a drive mechanism turns the armature of the gen-erator thereby creating electricity. The control system manages the interface to the load. Because of the speed variability of the wind, wind turbines have a DC power output.

Most wind turbines do not begin to generate any useful power until wind speeds reach 7-10mph and do not generate rated power until wind speeds reach the mid 20mph range. With that in mind small Wind Turbines in the 400W-1kW range are often paired and act as a supplemental power source with another power generation technology like solar due to the intermit-tent nature of wind. Newer advances in turbine technology like over speed protection can prevent damage to turbines when wind speeds approach high levels by automatically and individually adjusting blade pitch to the wind force. Temperature compensated charge control and diversion control can also help charge batteries at the right temperature and automatically divert surplus power to a dump resistor block to maximize operation.

“Wind Turbines are best suited for areas which average windspeeds of

12mph or greater“

• “Green” Energy Producer

• Non-Polluting

• No Ongoing Fuel Costs

• Useful Power Isn’t Generated Until Speeds Reach 7-10mph

• Rated Power Isn’t Generated Until Speeds Reach Mid 20mph Range

• Can be Noisy While Operating

• May Have Negative Impact on Wildlife (Birds)

• Requires Periodic Maintenance

Wind

SuperWind SW350 Micro-Wind Turbine (pictured)


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Solid Oxide Fuel CellsA Solid Oxide Fuel Cell (SOFC) is an electrochemical reaction device that converts fuel and air into electricity. These fuel cells consist of two elec-trodes (the anode and cathode) that are separated by an electrolyte. Fuel is added to the anode side of the fuel cell and air is added to the cathode. Electricity is produced when the fuel and oxygen from the air combine forming water. One of the key differences between SOFC and most fuel cell technologies is the process in which electricity is produced. While most fuel cells generate electricity by moving fuel through electrolyte, a SOFC moves oxygen from the air through electrolyte. The result is a system that is able to process conventional fuel such as propane and natural gas.

Powered by commercially available and low cost propane or natural gas, Solid Oxide Fuel Cells have the ability to sit in a standby mode for months at a time monitoring battery voltage and are then able to automatically start when the primary power source is lost ensuring critical applications have 100% reliable power or to operate as a primary power generator in remote applications. When compared to other fuel cell solutions, a SOFC offers a much broader environmental operating and storage envelope. Because a SOFC utlilizes a ceramic electrolyte they are not susceptible to freezing and thawing cycles that are a com-mon problem for fuel cells that use a hydrated polymer membrane such as Proton Exchange Membrane (PEM) fuel cells. A SOFC can operate in very cold climates (-40°F to 122°F), whereas other fuel cells may require continuous electrical energy input or the unnecessary consumption of fuel to prevent freezing. Temperature compensated charging algorithms provide accurate and optimized battery state of charge management regardless of changes in ambient conditions which minimizes the # of charge cycles to maximize fuel cell efficiency and extend the functional life of the backup batteries and consume less fuel.


“SOFC” Advantages: “SOFC” Disadvantages:

• Reliable Starting After Extended Storage

• Runs on Readily Available & Low Cost Propane or Natural Gas

• Wide Operating Range (-40°F to 122°F)

• Zero Maintenance (no moving parts, oil changes, etc.)

• Easy Integration (utility grid, solar, wind, batteries, generators, etc.)

• Clean“Eco-Friendly” Energy Producer

• True Standby Mode (only runs when needed)

• Quiet Operation

• Requires Local Fuel Source for Operation

• Power Isn’t Instantaneous (approx 30 min startup)

• Not Well Suited for 24/7 Prime Power Applications

• Needs Air/Ventilation for Operation (can’t be confined)

• Larger Upfront $ than Diesel/Gas Generators

• Stack Life - 250 cycles or 3,000 Hours (before replacement)

Fuel Cells

Ultra-USSI P250i Solid Oxide Fuel Cell (pictured)


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Proton Exchange Membrane Fuel CellsA Proton Exchange Membrane (PEM) Fuel Cell is an electrochemical con-version device. A PEM fuel cell is comprised of two adjacent chambers - the anode side and the cathode side - separated by a membrane. Hydrogen gas from the fuel processor enters the anode side where the atoms release their electrons when reacting with a platinum catalyst on the membrane. The anode chamber then becomes flooded with free electrons and with hydrogen protons (hydrogen atoms stripped of their electrons). The positively charged hydrogen protons pass through the membrane into the cathode side of the fuel cell. The electrons exit the anode side and flow into an external electri-cal circuit. After running through the circuit, the electrons re-enter the fuel cell on the cathode side, completing the electrical path. On the cathode side, the hydrogen protons that passed through the membrane combine with the free electrons and with oxygen molecules to produce pure water and heat.

Like engine generators, fuel cells require a local fuel source - with the amount of operating time dependent on local fuel storage capability and refueling intervals. A fuel cell operates best at load conditions near its rating, as its not well suited for very light loading. Current PEM designs are best suited for “backup” power applications rather than continuous prime power applications. PEM design fuel cell stacks have a shorter life expectancy as compared to other technologies discussed in this paper. While PEM design fuel cells expected operation lasts several thousand hours and is quite adequate for years of standby and/or backup service, a 24/7 operation would require the fuel cell stack to be changed out every few years which would get $ expensive. PEM fuel cells do not provide instantaneous power and different designs have varying start-up times that range from a few seconds to several minutes. Some designs will incorporate a small battery bank or ultra capacitor to bridge the startup time.


“PEM” Advantages: “PEM” Disadvantages:

• Extended Run Backup Power

• Onsite & On-Demand Hydrogen Production

• Low Maintenance

• Very Low Emissions

• Clean“Eco-Friendly” Energy Producer

• Quiet Operation


• Power Isn’t Instantaneous (approx 30 min startup)

• Not Well Suited for 24/7 Prime Power Applications

• Hydrating of Stack is Required Periodically

• Larger Upfront $ than Diesel/Gas Generators

Fuel Cells

Ballard (IdaTech) ElectraGen ME Fuel Cell (pictured)


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Thermoelectric Generators Thermoelectric Generators (TEG) are extremely reliable, low maintenance, long-life generators which provide continuous DC power by converting heat directly into electricity. As heat moves from a gas burner through a thermo-electric module, it causes an electrical current to flow. A hermetically sealed thermoelectric module, called a thermopile contains an array of semicon-ductor elements. When heat from a burner is applied to one side of the thermopile and the other side is kept cool via cooling fins, the temperature difference across the thermopile creates steady DC electricity with no mov-ing parts. The technology dates back to the 1960s and has been deployed around the world and in space.

TEGs typically range in output size from 15 to 550 watts and can be com-bined to power applications requiring up to 5,000 watts. They are designed to run on either propane, butane or natural gas. Outputs can provided to match virtually any DC or AC voltage requirement. TEGs are designed for continuous operation; which means that expensive battery systems, which need maintenance and periodic replacement, are not a required component of this power system. If batteries are used to cover high peak loads, TEGs operate in float charge mode which assures long battery life. TEGs are well suited for both prime and standby applications, though like a fuel cell, they do not instantly produce full power upon startup. Requirements for opera-tion of TEGs include: a mounting stand for the generator (to keep it from being inundated with water or snow), a local fuel supply (propane, butane or natural gas), and electrical connections to the load. A small battery bank may be integrated to cover peak loads, bridge the startup time or to provide emergency backup.


TEG Advantages TEG Disadvantages

• Solid-State Design Ensures Trouble-Free Operation & Reliability

• Well Suited for Prime Power Applications

• Low Maintenance

• Competitive Capital & Operating Costs

• Thermopile (20+ year) Life

• Operation in Any Climate (hot, cold, wet, dry)

• Small Footprint

• Batteries are Not Required Component


• Power Isn’t Instantaneous Upon Startup

• Low Operating Efficiency

• Not Suited for Applications Higher than 5kW

• Larger Upfront $ than Diesel/Gas Gensets

• Doesn’t Like to be Cycled On/Off

TEGs

Gentherm Power Technologies Thermoelectric Generator (pictured)


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Stirling EnginesStirling Engines combine free piston technology with advanced combustion capabilities to efficiently transform propane, natural gas, ethane, biogas and multiple associated gas streams into electricity. The external combustion engine and automatic control system enable the generator to produce steady, dependable power up to 6kW. Using a highly efficient thermodynamic pro-cess, a free-piston Stirling Engine (FPSE) generator can create electricity from virtually any heat source. The heat input creates a temperature differential across the engine causing the helium inside the engine to expand and contract, which in turn drives a linear reciprocating motion of the piston. The FPSE directly converts the reciprocating motion of the piston into electrical power via the integral linear alternator. A Stirling Engine has few moving parts, no direct-contact points that cause wear and require lubrication thus making it a truly maintenance-free technology that offers long-life performance; two key features that make it an ideal power source for remote site applications.

Stirling Engines feature a flexible and modular design, a package that can be tailored to run on a variety of gas sources and provide a broad range of pow-er output architectures to meet electrical requirements for remote sites with the following power ratings available: 120/240VAC -16 amps @ 240V (3840 watts), 24VDC - 4800 watts and 48VDC - 5650 watts. Units can be paralleled to power larger requirements. Stirling Engines are suited for both continuous prime or intermittent backup power and have a 60,000 hour design life with zero maintenance needs. Stirling Engines can be easily integrated with existing power infrastructure like solar & wind and are capable of operating between -40°F to 122°F to meet a variety of hot and cold climates.

Stirling Engine Advantages Stirling Engine Disadvantages

• Well Suited for Continuous Prime & Backup Power Applications

• Zero Maintenance (Hermetically Sealed Engine)

• 10-15 Years of Continuous Operation

• Ultra Quiet Operation

• Battery Charging Capability

• Can Operate Via Wide Range of Fuel Sources


• Larger Upfront $ than Diesel/Gas Gensets

• Power Isn’t Instantaneous Upon Startup (90 seconds rampup)

Stirling Engines


Qnergy Stirling Engine (pictured)


RedHawk Energy Systems, LLC 10340 Palmer Rd., S.W.

Pataskala, OH 43062

ph: 740-964-4000 www.redhawkenergy.netScan QR Code

About Us

About Us RedHawk Energy Systems, LLC is a value-added manufacturing subsidiary of the Arthur N. Ulrich Company. Since the early 1980’s, we’ve helped commercial and industrial customers tackle their critical prime and back-up power challenges with innovative solutions ranging from a few watts to several kilowatts. Our customers include virtually every Class 1 railroad in North America, shortline railroads, midstream, upstream and downstream oil & gas companies, telecommunication companies, shipping companies, government agencies, Fortune 500 & 1000 corporations and many others.

Solar Power Systems

Wind Turbines

Fuel Cells

Thermoelectric Generators

Stirling Engines

Hybrids

Batteries

Battery Boxes

Battery Enclosures

Battery Accessories

Engineering Services

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Copyright © 2017 All Rights Reserved RedHawk Energy Systems, LLC

technical paper - redhawk energy

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