Thermal generation is the process of generating electricity through the use of thermal energy, or heat. Thermal energy is used to produce steam which drives a steam turbine and generator, producing electricity. Production of electricity using thermal generation methods is common and many different fuel types can be used. Despite which type of fuel is used, the process of generating electricity is similar.
Thermal Energy Types
Bioenergy
Bioenergy is the process of creating energy through the combustion of biological materials such as forestry, agricultural, or livestock waste (plant material, manure, etc.). Bioenergy generation facilities are typically larger in scale and as such are not suitable for residential use.
Biomass technology, which burns wood or crop waste to produce electricity, is considered carbon neutral since the carbon dioxide released during combustion is part of the natural carbon cycle of the vegetation. This carbon would be released to the environment upon decomposition of the vegetation after its death. Other pollutants may still be released into the surrounding environment due to the combustion process, although it is often considered far less harmful than the burning of fossil fuels which are used in traditional thermal generating processes. The use of pollution control measures can be implemented to reduce this impact.
Bioenergy systems can be operated to generate energy around peak demand, but in order to be cost effective; the system must have enough available feedstock (combustible materials) to operate consistently.
Technologies also exist that allow for biomass feedstock to be used for the production of liquid fuels, meaning that a grid connection may not be required.
Landfill Gas
Landfill gas is created by the natural decomposition of organic waste in a landfill. The gas that is created from this decomposition process is primarily methane, which can be combusted to produce energy. Landfill gas generation needs to have a consistent supply of gas to combust in order to be cost effective.
Landfill gas is created by the natural decomposition of organic waste in a landfill and consists primarily of methane. The combustion of landfill gas can be used to create energy. Landfill gas generation facilities are typically larger in scale.
Although not a renewable energy in the strictest sense of the word, the use of landfill gas a fuel source does have benefits. It allows for the use of a resource that would otherwise be wasted, and offsets energy generation from the combustion of fossil fuels. Furthermore, landfill gas consists primarily of methane, which is known to have greenhouse gas properties which are even worse than carbon dioxide. The combustion process actually converts this methane into carbon dioxide, ultimately reducing the total greenhouse gas impact of the landfill.
As with any combustion process, pollutants may still be released to the surrounding environment. The use of pollution control measures can be implemented to reduce this impact.
Energy from Waste
Energy-from-waste is the concept of generating electricity from waste that would have otherwise gone to landfill. There are several available technologies, but in principal, the waste itself is burned to produce thermal energy. This differs from landfill gas, in which it is only the gas from the decomposition of solid waste already in a landfill that is burned. Energy-from-Waste generation facilities are typically larger in scale.
Like landfill gas, energy-from-waste is not actually a renewable energy but does have benefits. It is first and foremost considered a waste management solution and an alternative to land fill. Like the use of landfill gas to produce electricity, it can offset energy generation from the combustion of fossil fuels and ultimately reduce the total greenhouse gas impact of the decomposing waste due to the conversion of methane into carbon dioxide.
Due to the fact that waste materials are being combusted, there is a possibility for harmful pollutants to be released into the air. This can typically be mitigated to meet provincial air quality criteria through the use of air pollution control. An energy-from-waste facility would also have environmental concerns typical to a waste transfer station, such as potential for leachate.
The amount of available feedstock within the area (i.e. household waste) and public opinion would be limiting factors in the development of an energy-from-waste facility.
Technologies also exist that allow for waste feedstock to be used for the production of liquid fuels, meaning that a grid connection is not necessarily required.
Combined heat and power (co-generation)
With any thermal generating process, there is the opportunity for the use of Combined Heat and Power (CHP) applications. A CHP generating facility is one that produces electricity, but also produces useable heat from the process. In a typical thermal generating facility, this heat is wasted. The use of CHP technology allows for an increase in overall efficiency, ensuring the use of the most energy from the process as possible.
Excess heat is used to offset the heating needs in other areas of the plant, or in nearby buildings (possibly utilizing a district energy system). One limit to the use of CHP technology is that the user of the generated thermal energy must be located near the facility due to physical constraints with transporting heat.
CHP technologies could be integrated into any of the thermal generating processes described above.
Solar Thermal
Solar thermal energy is the use of the sun to collect energy in the form of heat. A basic example of this would be a small solar thermal water heater; it consists of a panel of tubing which is filled with water. When installed on the ground or on a roof, the sun heats this water for use in the home. This can also be done on a larger scale to serve large buildings or industries with hot water needs.
This technology doesn’t generate electricity, but can be used to reduce energy costs related to water heating. Technologies also exist that can use thermal energy to generate electricity by producing steam, but these technologies are typically placed in climates with maximum sun exposure.
Geo Thermal
Geothermal energy is the use of the earth’s thermal (heat) energy to heat and cool. Geothermal energy can be used directly and also for electrical generation. Electrical generation using geothermal technology is primarily limited to geographical locations with access to high levels of geothermal activity where temperatures within the earth are high, such as those found near tectonically active areas.
In areas without significant geothermal activities, such as our community, electricity generation and heating from geothermal energy is not possible, but geothermal heat pumps can be used.
At a depth of about 2 metres, the temperature of the earth stays relatively stable and is not affected by the temperature of the surface. A typical geothermal heat pump consists of several piping loops placed within this stable temperature zone. When water or another fluid is pumped through these pipes, heat can be gained or lost, reducing the energy required for space heating or cooling. A geothermal heat pump does not generate energy, but can be used to help offset the amount of energy used for heating and cooling, lowering the associated costs.
Energy Storage
Many renewable energy generation types are intermittent, meaning that there is no control in when the energy is produced. Furthermore, energy from intermittent sources is not necessarily produced when it is needed. For example, solar generation only produces sunlight during the day, but what if you need energy in the evening or at night? Energy storage, usually in the form of batteries, is required.
Conventionally, off-grid renewable energy generation systems have been limited by energy storage. Due to capital, operational, and maintenance costs, as well as a loss in overall electrical efficiency, the implementation of traditional battery storage systems has decreased the financial viability of off-grid renewable energy systems.
New technologies have and are being developed that can reduce the financial burden of battery storage systems. These technologies include more cost effective and efficient batteries as well as charging/discharging algorithms and configurations that can increase overall efficiency. In addition, means of energy storage other than electrical batteries are also available, such as the use of hydrogen fuel cells and water pumping/storage for use in hydroelectric generation.
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Cambium Indigenous Professional Services
1109 Mississauga Street, Curve Lake First Nation, Ontario K0L 1R0