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Composting • Organic Farming • Renewable Energy • Greenbuilding |
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What is renewable energy? Renewable energy refers to energy derived from sources that are naturally and continually replenished, such as wind, solar power, geothermal, hydropower, and biomass. These non-fossil fuel based resources can keep producing indefinitely within the human time-scale, without being permanently depleted. Use of renewable energy resources, as opposed to combustion of fossil fuels, can reduce the production of greenhouse gases as well as air pollution. The Macoskey Center demonstrates several renewable energy alternatives, including:
Photovoltaics (PV) is the direct conversion of sunlight to electricity. Sunlight hitting a semiconductor surface creates an electric potential, which can be collected and stored or converted directly into direct (DC) or alternating (AC) current. Groups of PV cells can be arranged into arrays, or logical layouts, and connected together for greater energy collection. With the appropriate power conversion equipment, PV systems can be used alone to supply electricity to a building, charge batteries or power machinery. They can also operate in parallel with and interconnected to the local utility grid.
The Macoskey Center utilizes five types of PV arrays: grid-tied, building-mounted, greenhouse, the renewable energy toolkit (RET) and the fence energizer.
The array faces south and collects direct sunlight. The angle of the array can be adjusted for maximum solar absorption. This system is tied into the local utility company. If the system generates more power than the house is using at any given time, it feeds back into the utility grid and the Center is credited for it (the meter turns backwards). Conversely, if the house load is greater than what the PV system is generating, we can draw power from the grid. Data on both power generation of the system and power consumption in the house is constantly recorded, and can be viewed with the web-based Fat Spaniel energy monitoring system. See the current energy generated by the grid-tied PV system
The building mounted PV system provides the Macoskey Center with a backup electricity source. The PV panels, located on the roof of the house, collect solar power which is stored in 12-volt batteries in the sunspace of the house. With a small inverter, the stored energy can be used for a variety of applications, including running small-load household appliances.
The system uses 3 - 116 6v 375 Ah batteries to store energy for use when the sun is not shining. Energy generated by this system provides all the electricity needs for the greenhouse.
This system was constructed by students and volunteers during a Spring 2007 workshop.
The renewable energy toolkit (RET) consists of a portable PV power
source and an electric cultivator. To create the solar power
cart, a commonly available garden cart was modified to hold
adjustable photovoltaic panels and hardware.
Two Siemens 75 watt solar modules provide 12 volt DC current to a Prostar 12 charge controller, rated at 4,297 watt hours per week (from May through September) under average insolation conditions (4.12 kWh/m2/day).
For demonstration purposes, the power cart is connected to a single-row track-laying cultivator unit manufactured by Sam Beechy and Sons. The unit has a cultivation bar with adjustable tines for secondary tillage in row crop systems, and is available with a hiller for making raised beds. When a 140 watt inverter is linked to the controller, the cart can be used to operate a laptop computer, portable radio, and other low amp devices. Heavier loads can be accommodated by a 600 watt inverter directly linked to one or more batteries.
The cultivator was purchased without the standard 3 hp gasoline engine attached. Modifications were made to the forward frame to accommodate a steel battery mounting plate; and the handle assembly was raised 4 inches to clear the electric motor installed at the rear of the frame. The original idler pulley clutch was relocated to a position under the motor. The permanent magnet 12V DC electric motor was custom fabricated to our specifications, and produces 1.5 Horsepower at 1,800 RPM, while drawing up to 128 amps.
Feasibility and siting of the system was based on a one-year study of wind speed and direction, carried out by an SRU graduate student.
Data on both power generation of the system and power consumption in the house is constantly recorded, and can be viewed with the web-based Fat Spaniel energy monitoring system. See the current energy generated by the wind turbine system
A fire is built in the main burn chamber twice a day. The chamber of the stove holds up to 60 lbs. of wood. The fire burns at extremely high temperatures, up to 2000º, which means the heater produces 40% more heat from the wood than a regular stove would. While the fire burns, gases and flames are pulled into a secondary burn chamber. There, the gases are re-combusted and burn off any impurities not burned in the primary burn chamber. These super heated gases are then channeled through the interior of the heater. This is the process in which the exterior masonry is given a chance to heat up. The high thermal mass of the exterior masonry provides slow, even heating once the high-temperature fire has burned. Once the super heated gases flow past the exterior heater walls, they are then circulated throughout the heater and drawn up the chimney. The end result of this complex burning process is a gas emission that is 98% clean, leaving no harmful gases to be vented into the atmosphere.
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The Robert A. Macoskey Center at Slippery Rock University 247 Harmony Road • Slippery Rock, PA • 16057 • (724) 738 - 4050 • macoskey.center@sru.edu |
Renewable
Energy
use of wind power in the 
The grid-tied PV system at the Macoskey Center is located southeast of
Harmony House. The 2.4 kW PV array is constructed from 20
Evergreen Solar EC120 12v PV modules and uses a Sunny Boy 2500U PV
240V AC Intertie Inverter. 
This
1.2 kW off-grid PV array was constructed from the PV panels formerly
used to provide energy to the Harmony House. The old PV array
was decommissioned and the 60w panels were reused to construct this
20 panel system.
A
practical run time that protects battery integrity has been
established of approximately 1.25 hours when 3 batteries are used.
The
fence energizer system is another portable PV system, similar to the
RET. A PV panel is attached to a modified toolbox that
contains a chargeable 12V battery. The collected power is fed
through an energizer unit (blue unit in photos). The unit
energizes the electric poultry netting in our rotational grazing
system, keeping predators such as
foxes away from the chickens.
The
wind turbine system at the Macoskey Center is located on the ridge
behind the Market Garden, to the south of Harmony House. The
turbine is part of a grid-intertied system, which provides an emissions-free source of electricity for Harmony
House.
Wind
causes the three-blade rotor to spin and drive the generator inside
the tower. The crescent-shaped tail of the turbine keeps the
rotor facing into the wind, and kicks it out of the wind when winds
speeds are high enough to damage the system.
The
masonry heater at the Macoskey Center can provide almost 90% of the
BTU's needed to heat Harmony House. It is a Finnish-style
heater, chosen for its heating and baking capabilities. 