Diesel engines and gensets have undergone significant technology modifications over the past few years in order to become more environmental friendly and efficient in operations. A recent technology trend has been the use of hybrid systems, which combine diesel engines with at least one renewable energy source. Such systems not only reduce the fuel cost, but also generate power that is cleaner. The deployment of energy storage battery solutions in a hybrid system adds to its benefits and makes hybrid systems more viable. Another technology trend that has gained traction is the use of smart diesel engines, which deploy digital solutions to control the operations, distribute load and ensure efficient combustion. Besides this, with the imposition of stricter environmental norms, diesel gensets are being equipped with selective catalytic reduction (SCR) systems and exhaust gas recirculation engine in order to reduce the harmful emissions to a large extent.
In the diesel engine and genset space, the use of hybrid technology solutions is fast gaining traction. These systems combine diesel gensets with at least one other renewable energy source such as solar and biomass. Such a system is cost efficient as it reduces the dependence on expensive diesel fuel, offers clean energy generation in compliance with the environmental norms, and provides uninterrupted power supply, thus resolving intermittency issues. The most common hybrid technology combines diesel gensets with solar photovoltaic systems. Such a system has the reliability of diesel gensets and the cost effectiveness of solar power systems. Solar energy produced by the modules during the day reduces the load on diesel gensets, saving fuel and thereby reducing operating costs. On the other hand, power from the diesel engine provides the requisite frequency and voltage to firm up the direct current produced by solar panels and to stabilise the load.
In the hybrid genset space, one of the emerging technologies is storage batteries. Integrating storage batteries in hybrid configurations helps further reduce diesel consumption as the battery bank provides the frequency to the current produced by solar panels during daytime or in the event of load failure from the grid in on-grid locations. Although adding battery storage to diesel-solar hybrid systems involves high capex costs initially, it also improves operational efficiencies during the lifecycle of the system and is cost effective in the long run.
Diesel gensets with WHR systems
One of the technologies that help in enhancing the efficiencies of diesel engines and gensets is waste heat recovery (WHR) systems. A WHR system recovers heat from steam and transforms it into electrical energy for utilisation. This is done using energy conversion devices like regenerators, recuperators and economisers. The exhaust of a diesel engine contains 40 per of the input energy and usually this energy is expelled into the environment and gets wasted. By using a WHR system, energy consumption can be reduced by 5-30 per cent.
Environment-friendly diesel gensets
Diesel gensets with SRC
The latest diesel engines are using technology solutions that help in meeting the prescribed emission norms. In order to manage NOx emissions, the diesel gensets use SCR. In SCR, an aqueous urea solution (AUS32) is introduced into the exhaust stream. Ammonia from AUS32 combines with NOx in the presence of a catalyst to form harmless by-products like nitrogen and water vapour. The SCR system is a simple system that offers better power and higher fuel economy due to higher combustion efficiency. Clean combustion ensures higher reliability of engines. It is a robust system to deal with lower quality of fuel and provides the customer a longer engine life. It is one of the most cost-effective and fuel-efficient emission control technologies available for diesel gensets.
In an exhaust gas recirculation (EGR) engine, a portion of the exhaust gas, which contains unburnt fuel and carbon, is re-circulated into the engine. This reduces the combustion temperature, thus bringing down NOx emission level. However, the EGR system has lower combustion efficiency and a higher heat rejection. This causes unburnt carbon and fuel to enter the system, which could impact its reliability and durability.
There is a growing demand for gas generators. Natural gas can be used to power both emergency and portable generators and is regarded as one of the most affordable and effective non-renewable resources for power generation. The consumers are also opting for retrofitting of the existing diesel gensets, which would enable them to run the existing generators on a combination of diesel and gas. A retrofitted diesel generation set could run on a combined ratio of 60 per cent gas and 40 per cent diesel. The cost of retrofitting is Rs 0.4 million-0.5 million, which can be recovered in about six months. Indraprastha Gas Limited is planning to replace diesel generators with gas generator sets in housing complexes and factories, pitching it as a cheaper and environment-friendly option for the national capital region, which is under threat from rising pollution levels due to polluting factories, increasing number of vehicles and large-scale construction activity.
Silent diesel gensets
The noise in a diesel genset occurs mainly when starting the engine as the fuel is injected into the pre-chamber and is forced to vapourise at a high temperature. However, recent advancements in sound attenuation materials and strategies enable reduction in noise levels to a significant extent. This is done by fitting the pre-chamber with sound attenuation pockets. These pockets are spaced and designed such that they nullify the detonation waves caused during combustion. Alternatively, these pockets are filled with porous or metallic ceramic pellets, which are coated with platinum or rhodium. Platinum and rhodium act as catalysts to achieve complete combustion and the pellets attenuate the noise levels. Other modifications involve placing attenuating materials such as porous ceramic or sintered metal near the mouth of the passage connecting the pre-chamber to the combustion chamber.
Smart diesel gensets
Smart diesel gensets consist of digital controls instead of analogue controls installed in conventional systems. Digital controls are highly integrated and report the real-time status of all aspects of a diesel engine – fuel, engine oil, coolant, engine temperature, battery status, transfer switch status, etc. These systems can be connected to a computer to enable the remote monitoring of operations. Digital controls also increase fuel efficiency and reduce emissions by making automatic adjustments to the fuel rate input and injection timing under varying load conditions. It allows common centralised monitoring and control of the whole system including diesel genset mechanical and electrical data, electrical parameters, fuel supply, lubrication and air and water cooling system. A digital diesel genset enables auto-synchronisation and fast synchronisation, eliminating any possibility of manual inaccuracy of operation. It allows auto-load distribution among all diesel gensets and auto-load shedding for system safety, preventing power cuts in critical equipment. Besides, an internet of things enabled diesel genset offers real-time insights into fuel consumption and theft detection.
Net, net, a number of advanced technological solutions are available in the diesel genset and engine space, which offer environment friendly and efficient combustion. However, for best results, it is essential to identify the most suitable technology depending on the needs and requirements of end-consumers.