5. Different fuels could be used in the same boiler (Greenpeace UK, n.d).
6. CHP plants can be highly autonomous resulting in the reduction of operation and maintenance cost as well as the labours (Al-Mansour and Kozˇuh, 2007). Smith et al (2013) found that, CHP results in the reduction of the consumption of fossil fuels derived energy and CO2 emissions compared to the absence of CHP. This is highly achievable through the capture of waste heat associated with the electricity generation process of CHP through periods of low demand.
Figure (4) represents the carbon savings would be derived from the application of district heating networks derived from both renewable and non-renewable sources compared to conventional way of heat production. It can be figured out that, district heating networks operated by renewable source of fuels, like; biomass have higher carbon saving than non-renewable ones like natural gas. In general, DHN has better carbon saving than other technologies (PÖYRY Energy Consulting, 2009).
However, CHP system has some disadvantages. Firstly, it works at constant load more efficiently, while the heat and power demand of a building or a site served by it is fluctuating. Therefore, during the period of low demand there is loss of excess thermal energy compared to lack of it during high demand periods. The use of thermal energy storage is a helpful way to store the excess energy not used through periods of low demand. This will increase the efficiency, profitability and the period of CHP operation (Al-Mansour and Kozˇuh, 2007). Secondly, the application of CHP in district heating requires heat distribution networks to convey the produced heat to end users. This network is known to be expensive, which add to the cost of the CHP plant. Moreover, it is difficult to install and maintain this piping system into the existing buildings and dwellings (Finney et al, 2012).
Factors affecting the viability of CHP:
There are several factors that affect the investment in CHP including the policy of climate change mitigation and carbon emissions, financial incentives and energy policy. Most of the studies for the viability of CHP investment considered different factors and associated possible values like carbon price and carbon reduction targets, fuel price and discount rates which are highly influenced by governmental policies, energy market, money values and risk considerations (Hinnells, 2008).
Technical/ Practical Factors
Technology plays a role in the improvement of the efficiency of electricity generator in CHP which uses excess heat from the process of electricity generation. Cost of energy used and associated carbon savings from CHP are highly dependent on the efficiency of electricity generation, due to inefficiency in the central electricity generation, and the improvement in heat recovery. Therefore, increasing the efficiency of electrical generators will improve CHP performance in the use of excess heat. This is can be achieved...