One might find it difficult to categorize CHP technology otherwise also known as cogeneration as a Renewable Energy Source. In spite of this one finds Biomethane driven CHP plants nowadays in many parts of the world, including the Europe, which are interestingly fully fledged Renewable Energy Units.
Biomethane CHP plants need to be appreciated in more depth as they address many a complex environmental issue as well in surprisingly simple ways. If you leave them aside for the time being, do to conventional CHP technology deserve to get the distinguished mantle of being labeled a sustainable process?
A conventional generating plant uses a Fossil Fuel Burning prime mover (generally a reciprocating engine or a turbine) to generate electricity. This process at best about is 50% efficient .The remaining quotient of energy is simply thrown out to the environment as waste thermal energy.
In CHP units this waste heat is recovered in various ways so that the over all efficiency can be as high as 85%.
Sustainability which as applied to a human community is the status of meeting the needs of the present without
comprising the ability of future generations to meet their own. Fossil Fuels being a natural resource that exist in fixed quantities and cannot be replenished as fast as it is consumed is non renewable.
So it is clear that by definition CHP unfortunately cannot be classified as a sustainable Renewable Energy Process.
Consequently CHP does not get the VIP treatment reserved for other Renewable Energy Systems. In spite of this the benefits it offer are immense to the consumer whether it is the State or the Industrialist
- Reliability: CHP s has been in use in Ireland for at least 3 decades! In the context of Ireland the CHP power generation is distributed in the grid where as the wind turbine (the leading renewable energy generation system) is mainly confined to the West. And in this region you will find the network is the weakest. And when the wind speeds are high collectively all units in a wind farm would be shut down and will be of no use to the main power grid. Further, by nature the power generation is intermittent due to fluctuating wind speeds. One should not undermine the role of wind turbines as a reliable source of renewable power. But in relative terms CHP which can operate at 100% at almost all the time is more reliable it appears!
- Impact on the Power Grid: According to authoritative publications CERN/ESBNG/Iregrid have placed a moratorium on the new wind farm connections due to their inability to cope up with it resulting from system limitations. Unfortunately this necessitates public funding to upgrade. The CHPs luckily do not need new connections as these will be replacing old plants mostly and even if it is a totally new installation the site will not need heavy infrastructure improvements. The CHPs distributed in the grid would in addition reinforce and stabilize it.
- Impact on the environment: Unlike the renewable energy generated power systems the CHPs will not be distributed in the natural or reserved environments. In most instances they would be replacing inefficient existing units on one to one basis in urban surroundings. The new installations too will have them housed in or near building structures. Large tank farms around production facilities will be minimized.
It may be worthwhile to consider CHPs when you look for your new power plant and heating system if your requirement is 20 kw or above.