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Northel Energy
Sales & Service Agreement

In August 2011, we partnered with Northel Energy to provide sales and service support in the United States for their mid-range Wind Turbines (7.5kW - 250kW). To learn more click here.

 

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Upcoming Trade Show

RSSI 52nd Annual C&S Exhibition May 21-23, 2012 Duke Energy Convention Center Cincinnati, OH

There are several choices of technologies available related to power systems for remote site prime and backup power systems. This guide is focused on identifying those power systems that are most appropriate for a given application in the power ranges of 5 to 5000 watts. 

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

- Photovoltaic (Solar) Power Systems
- Wind Generators
- Fuel Cells
- Thermoelectric Generators (TEG)
- Extended Run Generators
- Hybrid Power Systems
- Battery Systems


While all of these systems 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.  The following information in this guide below should give you a good understanding of which power system is ideal for your particular application.  In any case we have a variety of engineering services available to help you determine which power system configuration best meets the needs of your application. For application support, email us at info@redhawkenergy.net or speak with a representative at 740-964-4000. 

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Overview of Technologies

Photovoltaic (Solar) Power Systems PV (solar) power systems provide a reliable source of DC power.  PV modules require very little maintenance with the occasional cleaning of modules, check of electrical connections, check of system regulators and check of battery storage systems being the only required maintenance annually.  PV systems operate on no fuel, rather "sunlight" and therefore don't incur ongoing fuel costs.  Most modules are designed and rated to provide reliable performance and life of over 20 years.  Nominal voltages of 12, and 24 volts can be scaled in a series and/or parallel configurations to accommodate an 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 multi-voltage DC or AC output. Application Considerations: Because PV systems are an intermittent generator of power, loads requiring power at all times other than when the sun is shining require an energy storage mechanism.  To accommodate loads that need to be powered through the night and over extended periods of inclement weather, batteries are used to provide an energy storage buffer.  Proper mounting structures are required to hold the individual PV modules in a system; allow integrated system wiring; and enable proper alignment and module tilt to optimize energy capture. Specific location factors will impact the structure design and should take into consideration wind loading, expandability, maintenance and exposure to vandalism. PV System Advantages: PV (solar) power systems are "green" energy producers, operate via sunlight and require no on-going fuel.  They produce no waste byproducts or emissions as they generate power.  PV System Disadvantages: PV (solar) power systems require a direct exposure to the sun hence they are a bit more susceptible to vandalism and theft.  Because of the efficiencies of the modules in converting sunlight to electricity, PV systems usually require a larger footprint than other power solutions of similar ratings.  Shading can present challenges in remote site areas with significant trees, hills or mountains and must be taken into consideration during the sizing of the system.	PV Solar Power System in a railway wayside application  Batteries are used to accommodate loads that need to be powered through the night and over extended periods of inclement weather PV Solar Power Systems are "green" energy producers, operate via sunlight, and require no on-going fueling Shading can present challenges in areas with trees, hills or mountains
Wind Generators  Wind generators typically consist of a rotor, electric generator, and a control system. The rotor, which looks much like an airplane propeller, is turned by the wind.  It is connected to a shaft which either directly or through a drive mechanism turns the armature of the generator thereby creating electricity.  Because of the speed variability of the wind and the typical applications in the smaller range, wind generators have a DC output.  The control system manages the interface to the load and storage batteries can provide a diversion for excess power that may be generated but not required by the load.  A variety of types and sizes of wind generators are available from the small (400 watt) to the large (megawatt).  For the purposes of this guide, we'll focus on small wind generators similar to the ones that we offer (non grid-tie wind generators in the under 5kW range). Application Considerations: Most small wind generators don't begin to generate any useful power until wind speeds reach 7-10 mph and don't generate rated power until wind speeds reach the mid 20 mph range.  Just like PV (solar) power systems, if loads need a continuous source of power, an energy storage system (batteries) should be used.  Because of the intermittent nature of wind compared to solar, the necessary energy storage system will be larger than for solar.  Often, solar and wind technologies can compliment each other in a hybrid power solution. Wind Generator Advantages: Wind is another form of renewable "green" energy and like sunlight; wind is a free resource.  Wind generators are also non-polluting and require no ongoing fuel expenses. Wind Generator Disadvantages: Wind generators can sometimes be noisy (during extremely winding conditions).  They may also have a negative impact on wildlife such as birds.  Because wind generators have a number of moving parts, as compared to PV modules, they therefore require more maintenance and attention leading to shorter lifespans.	Just like PV (solar) power systems, if loads need a continuous source of power, an energy storage system (batteries) should be used Often, solar and wind technologies can compliment each other in a hybrid power system configuration
Fuel Cells  Fuel cell systems are a power generation technology offering a reliable, clean, new source of energy that can be a cost effective replacement to traditional generators and battery-only systems.  For the purposes of this guide, we'll be concerned with the PEM type fuel cells only.  A PEM fuel cell is an electrochemical conversion device 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 electrical 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. Application Considerations: Like engine generators, fuel cells require a fuel source. The amount of operating time is dependent on the local fuel storage capability and refueling intervals.  A fuel cell operates best at load applications 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.  A fuel cell stack usually has a shorter lifespan as compared to other technologies in this guide.  While its expected operation lasts several thousand hours and is quite adequate for a standby or backup role, a 24x7 operation would require the fuel cell stack to be changed out every few years.  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 include a small battery or ultra capacitor to bridge the startup time. Fuel Cell Advantages: Fuel cells are a very clean power source. Emissions from PEM fuel cells are just heat and water vapor.  Fuel cells operate very quietly due to the fact that they have very few moving parts.  Fuel cells require very little maintenance annually.  Designs can be very robust and operate in all types of climates.  As a backup power source, the technology is particularly well suited for sitting idle for a very long period of time, but performing very reliably for an extended period of time once called upon.  Fuel cells are also considered to be a "green" energy source. Fuel Cell Disadvantages: Like engine generators, fuel cells require fuel storage and ongoing fueling requirements, which may impact where these systems can be deployed and their cost justification.  Fuel cells are not well suited for 24x7 prime power applications.	PEM Fuel Cell Stack Fuel Cell operation Some designs include batteries or an ultra capacitor to bridge the startup time
Thermoelectric Generators (TEG)  Thermoelectric generators (TEG) are extremely reliable, low maintenance, long-life generators which provide continuous DC power for a variety of remote site applications.  A TEG works by converting heat directly into electricity. As heat moves from a gas burner through a thermoelectric module, it causes an electrical current to flow.  A hermetically sealed thermoelectric module, called a thermopile contains an array of semiconductor 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 moving parts.  The technology dates back to the 1960s and has been deployed around the world and in space. Application Considerations: TEGs typically range in output size from 15 to 550 watts can be combined to power applications requiring up to 5,000 watts.  They are designed to run either propane, butane or natural gas.  Outputs can be be 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, do not instantly produce full power upon startup.  TEG Advantages: TEGs solid state design ensures trouble-free operation and high reliability.  A pro-active maintenance schedule for a TEG is 1-2 hours per year.  TEG systems have extremely competitive capital and operating costs for systems ranging from 5 to 5000 watts and above.  A single sealed thermopile has a 20+ year life expectancy.  TEGs can continuously operate in all weather conditions (wet, dry, hot, cold) and are not affected by dust and other airborne contaminants.  The physical layout/footprint of a TEG system is smaller than solar or other generator options.  TEG installations are low visibility and can be mounted inside security enclosures if required.  TEG Disadvantages: Like generators and fuel cells, TEGs require a fuel source to operate and fuel storage and refueling requirements can affect the suitability for deployment in a given application.  As power needs scale higher than 5kW, TEGs are not well suited from both a cost and application aspect.  As a power generating source, TEGs operating efficiency is lower than extended run generators and fuel cells.	TEG pictures from Global Thermoelectric 5 x 200 watt TEGs A small battery bank may also be integrated with the system to cover peak loads or to provide emergency backup TEG Remote Site Application
Extended Run Generators  Extended run generators are designed to deliver high quality, reliable, unattended prime power.  The engine component of these systems was originally developed with a focus on gas powered total energy systems with overall operating lifetimes up to 40,000 hours.  Extended run generators have robust internal combustion engines with tight manufacturing tolerances and special modifications allowing them to operate for extended intervals between oil, spark plug and filter changes.  They can be packaged as pure engine generator systems as well as micro CHP (combined heat and power) systems.  Low NOx and CO emissions and quiet operation make these systems environmentally friendly. Application Considerations: Extended run generators are fueled by either natural gas or propane.  They require a connection to a gas line or local fuel storage for their operation.  The local fuel storage must be sized to accommodate the desired interval between refilling based on the system load and fuel consumption of the engine.  These systems can be configured for various AC and DC output power.  System power ratings typically range from 1kW to 2.5kW.  Air for combustion and cooling is required as well as exhaust air flow.  These units can be used as prime power sources running continuously (maintenance/servicing required once per year).  These units can also be used as an intermittent standby source in conjunction with a hybrid configuration involving a secondary power source (solar, wind or batteries).  A hybrid configuration is typically utilized in applications that have high power requirements and suffer from shading conditions such as trees, hills or mountains during parts of the year.  Extended Run Generator Advantages: Extended run generators can handle higher and more varying power requirements more cost effectively than either solar or wind.  These systems are typically very efficient - up to 90% when heat recovery is used.  Compared to the typical small generator sets, these systems offer much quieter operation,  higher efficiencies, less required maintenance, lower emissions, and overall life expectancies are up to 100x longer.  These systems can easily be integrated into hybrid configurations. Extended Run Generator Disadvantages: Fuel storage and ongoing fueling requirements can impact where these systems can deployed.  Operating fuel costs can also impact the cost evaluation of the system as compared to solar or wind technologies whose fuel source is a free natural resource.  While maintenance and repairs are substantially lower than standard grade engine generators, these systems have several moving parts and require specific maintenance at specified intervals.	Extended Run Generator along Railway Wayside Application Local Fuel Storage for Extended Run Generator Hybrid Power System - Extended Run Generator & PV (Solar) Power System

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