Renewable Energy

Renewable energy technologies such as solar, wind, and micro-hydro do not contribute greenhouse emissions to the environment during power production.  While a majority of electricity produced in Belize is from commercial hydro-electric plants, over half of its total energy demand is filled by Mexico whose primary electric power generation is from conventional thermal systems using hydrocarbon based fuel sources such as oil and natural gas.  Onsite renewable energy systems help Belizeans reduce their dependence on municipal systems as well as their contribution to greenhouse gas emissions.  Burning renewable fuels such as biodiesel, wood and biomass contribute relatively little greenhouse gas emissions.  Using energy efficient lighting reduces greenhouse gases as well. Replacing one 100W incandescent bulb with a 23W compact fluorescent light bulb (CFL) will prevent 1140 pounds of greenhouse gas emissions over the life of the bulb.   Replacing ten 100W incandescent bulbs with CFLs saves as much carbon dioxide during the life cycle of the bulb as a typical sports utility vehicle or (similarly-sized car) produces during a year.

Solar panels, image courtesy of Karin M. Abell

We promote the use of a variety of renewable energy technologies to remove the financial, informational, technical, and cultural barriers to the implementation of personal and community-scale renewable energy projects. The first consideration for any electric system is to maximize the efficiency of the system.  This includes, but is not limited to, reducing electrical use wherever possible, using low energy lighting and appliances, using alternative energy sources wherever possible, and maximizing passive systems. We strive to generate sufficient electricity from renewable energy collected on site to cover the center’s entire energy demand. Following a site analysis to determine availability and quantity of renewable energy resources, we will design integrated systems utilizing a combination of solar, wind, and/or micro-hydro electricity production.

Other examples of simple electricity conservation measures we rely on include:

• Natural daylighting
• Low-wattage lighting.  CFL or LED (preferred)
• Motion detector control of passage lights
• High-efficiency appliances
• Appliance placement
• Cool cupboard and root cellars for bulk storage of goods that only require cool storage, such as: fruits, vegetables, drinks, baking supplies, cheeses, eggs, etc.
• Public zone, shared low-wattage freezers (if necessary).  If available, spring fed chill boxes are optimal

Image courtesy of Angela Kilby

Example of a small microhydro installation

Micro-Hydro: Depending on availability and magnitude of the resource, micro-hydro can easily be utilized as a primary power source.  Hydropower is ideal for off-grid applications because of the steady predictability of a running waterway (unless seasonal variation makes year-round power production impossible).  This means that less energy storage is required because daily power output can be measured and relied upon.  Hydro systems can be smaller in power rating than solar, because they operate all day and night (compared to solar which is producing only when there is sunlight).   Micro-hydro designs of any size should include the use of flowforms for the portion of water that is diverted to the powerhouse to re-oxygenate the water before it is returned to the main waterway.[1]  If an adequate hydro resource is unavailable or is insufficient as a primary power source, we design to combine it with solar or a hybrid solar/micro-hydro system.

Solar Panels: While solar (PV) panels remain the most expensive choice when it comes to home-scale renewable electricity generation, the solar cell technology has been around for decades (in the semiconductor industry) and has proven its reliability.  In fact, solar panels are so reliable that most manufacturers offer a 20-25 year standard warranty for their panels. They are available in many sizes and can be ordered as whole-systems, reducing the cost and requiring less specialized equipment to install than putting together a bookcase.  Solar panels are rated using standard test conditions of 1000 W/m2 with a cell temperature of 25°C.  This isn’t generally indicative of normal operating conditions which are closer to 800-850 W/m2 with 50°C cell temperature.  This means in general, solar panels will see 80% of the power listed on the manufacturer’s specification sheet.  This is important to remember when sizing a system.

Image courtesy of Tom Check

Remote wind turbine water pumping installation

Wind Turbines: Wind turbines are one of the least expensive renewable energy options because they can be locally produced.  Wind is ideal for smaller and/or less demanding applications such as water pumping – especially where the mechanical energy can be used directly because this kind of system generates maximum efficiency.  There are several regions in Belize with moderate to good wind resources, ranging from 5.6-7.5 m/s average annual wind speed.[2]  However, we do not usually consider it as a primary power source, because wind is highly unpredictable from day to day, requiring more storage capacity for non-windy days.   Instead, wind use is often best used as part of a hybrid wind/solar or wind/solar/micro-hydro system. 

Pumps:  For solar water pumping applications, DC motors are preferable because they can be directly connected to the PV array.  Centrifugal pumps with submersible motors are optimal for their efficiency, reliability and economy.

To Grid or Not to Grid:  Off-grid options for main power sources can be linked to backup grid power or generators, depending on the availability and economy of grid connection.  Whether or not a structure is grid-connected or relies on a generator/battery back-up system depends on what is available. One of the most efficient solutions is to connect to a grid that allows for net-metering.  Battery back-up systems are less efficient than grid connections due to conversion losses from the panels to the batteries and then from the DC batteries to the AC house load. Generally, this amounts to an average loss of 14% over non-battery systems.

HEATING AND COOLING

Because of the warm climate in Belize, we focus on design efforts that eliminate the need for air conditioning such as the following:

Active Systems:

• Ceiling fans draw heat through in-floor grates, windows, etc. for heat evacuation and air circulation

Passive Systems:

• Radiant second-floor heat controlled by in-floor grates
• Window shades and other shade structures for summer sun
• Cross ventilation for summer cooling
• Root cellars attached to the kitchen for increased cross-ventilation
• Strategically placed thermal mass to maximize interior coolness
• Fenestration, or the arrangement of windows, doors, skylights, etc.
• Low emissivity, double-glazed glass optimized for transmission and insulation (if required)
• Infrastructure orientation to minimize solar heat gain