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|Gas Turbine or Engine with Heat Recovery Unit
(Click for larger image.)
|Courtesy of EPA|
According to the International Energy Agency, power generation from non-hydro renewable sources including solar, wind, and bioenergy will exceed gas and nuclear by 2016, while renewable power is expected to increase by 40% in the next five years. While solar and wind are well known alternative energy sources, it is estimated that about 8% of world electricity generation capacity currently comes from cogeneration power systems.
The United States Environmental Protection Agency (EPA) explains, “Combined heat and power (CHP), also known as cogeneration, is the simultaneous production of electricity and heat from a single fuel source, such as: natural gas, biomass, biogas, coal, waste heat, or oil.” The system was likely first introduced by Thomas Edison in 1882 at his Pearl Street Station which combined heat and power, producing electricity and thermal energy.
Cogeneration already provides a substantial portion of the national power production in countries such as Finland (almost 40%) and Denmark (over 50%).
Cogeneration is more of a principle than a single technology, with the main advantage of CHP plants being optimal efficiency. Conventional power generation discards up to 65% of energy potential as waste heat while cogeneration plants have a conversion efficiency of 75% to 90% and are particularly useful in colder climates where the heat can be used for heating buildings and industrial processes.
A further benefit lies in the proximity of the average cogen facility to consumers of the power. There’s typically a 5% to 10% lose in transmission of electricity from traditional remote power stations isolated from consumers.
Environmentally friendly, the majority of today’s large industrial and commercial CHP applications are in the pulp and paper, chemical, refining, food processing, ethanol, and manufacturing sectors, which require vast amounts of electricity and heat, and typically run on natural gas which is generally believed to be the cleanest fossil fuel. As natural gas is in great supply across North America, it is free of geopolitical strife.
Additional benefits: Cogeneration systems use less fuel to produce the same amount of energy. And cogeneration is an integrated energy system that may be altered depending upon the needs of the energy user.
Gas fired cogen plants are common, but biomass fueled plants have the added benefit of using a renewable, practically inexhaustible fuel source. In a pulp mill, for instance, wood waste that would typically end up in landfills can be recycled and used as fuel for on-site cogeneration plants to provide power for the pulp mill and steam for operations. Any excess power can be exported.
Cogeneration systems play a crucial role in meeting North American energy needs and reducing the environmental impact of power generation from sources such as coal. As reported by social engagement platform good.is, it takes 876kwh to power a single light bulb continuously for a year which equates to 714 pounds of coal or 143 pounds for natural gas. Cogeneration systems require less fuel than these conventional sources as both heat and fuel are utilized to produce energy. And fuel sources such as biomass waste can be used to further lessen the impact on the environment. Because less fuel is burned to produce energy, CHP reduces greenhouse gas emissions. CHP’s high efficiency and reliability results in overall operational savings.
Fortress Paper has made a significant investment in cogeneration at its Fortress Specialty Cellulose Mill in Thurso, Québec where the company has expanded into the renewable energy generation sector with the construction of a co-generation facility. They are upgrading the on-site cogeneration facility to produce up to 25 megawatts of green energy. The company has also entered into an energy supply agreement with Hydro Québec to provide green power to the grid over a 15 year term.
Cogeneration exemplifies a demonstrated, cost-effective, and energy-efficient solution for delivering electricity and heat. As we make a transition to a more sustainable energy future, continued availability of affordable natural gas is crucial. Newer technologies such as fuel cells, with their small-scale applications, also play an important role in cogeneration’s future.
As more organizations invest in cogeneration, we will likely see a noticeable reduction in peak electricity demand. This benefits utility providers by decreasing infrastructure costs and alleviates upward pressure on electricity costs. As climate change caused by greenhouse gases becomes a growing global issue, the significance of CHP as a real way to reduce emissions is more obvious than ever.
Read Biofuels and Bioenergy: Processes and Technologies from Amazon.