Information from Triveni Turbines Africa
The power generation industry around the globe has been undergoing a sweeping transformation over the last few years, and this phenomenon is expected to continue in the coming years as well. The rapid depletion of fossil fuel reserves combined with the environmental impact caused by CO2 emissions has pushed the world to look for alternative sustainable energy resources. This urge to find a suitable substitute has resulted in changing energy generation mix and prompted the shift from conventional energy sources (fossil fuel-such as oil, gas and coal) to renewable energy sources.
There has been an increasing focus on replacing the existing coal-fired power plants with clean-fuel fired power plants to reduce the carbon footprint worldwide. Renewable energy comprising non-thermal (such as hydro, solar and wind) and thermal energy sources can play a vital role in reducing carbon emissions.
Bio-energy industry, the prime thermal energy source, turns unconventional feedstock into solid fuels (biomass or wood pellets, sugarcane residues and palm oil residues, etc.), liquid biofuels (ethanol, etc.) and gaseous fuels (biogas, landfill gas). These fuels are then used to produce electricity, heat and transport fuels.
According to an international report on solid biomass, at the beginning of 2020, there were around 4200 active biomass-based power plants worldwide, which had an installed power generation capacity of about 72,5 GW. The installed power generation potential through biomass-based power plants is expected to reach 90,9 GW by the end of 2029, by adding around 1250 plants. This would take the combined total to 5450 plants.
The endeavor to use locally available agricultural and forest residues have benefitted generating power closer to the point of consumption that has enabled the establishment of biomass-based independent power plants (IPPs). The IPPs played a prominent role in the generation of power that is supplied to the grid or specific customers. For most IPPs, a feed-in tariff (FiT) or power purchase agreement (PPA) provides a long-term price guarantee.
Industrial waste generated from agriculture and forest produce based plants like the rice mills, sugar mills, and palm oil mills, along with wood waste from pulp and paper mills, can be feasibly used as biomass to produce power for captive consumption. Through the appropriate use of steam and increased use of non-bagasse (e.g., wood waste) fuel for power generation, the pulp and paper industry is continuously concentrating on improving its energy efficiency.
At present, process heat accounts for the co-generation of around 70% of biomass power. While industrial process heating applications are powered by these heat sources worldwide, they are being used for district heating in European countries.
Steam turbine companies provide innovative solutions which use low-pressure steam generated through an extraction turbine for heating applications by producing both heat and electric power (CHP). The cost of power generated through this process is 14 to 15% lower than the cost of power generated through independent power plants. Furthermore, the customer can get only electric power through IPPs.
The power generated through CHPs is beneficial for the customer even in comparison to solar energy, which is a renewable energy source as the energy from the sun can be used only during the daytime, whereas the power produced through CHPs can address the combined heat and power requirements of the plant 24/7.
The rapid increase in electricity consumption and the growing carbon emission levels is creating the need for alternative energy solutions across the globe. Unleashing sustainable power generation is possible by increasing the focus on electricity generation through biomass energy sources that are cost-effective too, as they combine both heat and electricity.
Case study1: Biomass based power plant in Turkey
Driven by a 16 MW condensing steam turbine with an inlet steam parameter of 42 Bar and 450°C with 0,1 Bar exhaust
Challenge: Inconsistency in the availability of biomass fuel (forest waste, paddy waste, canola stalk, sunflower stalk, and sweet corn stalk) affects day to day operations. The variation of fuel input affected the boiler load, which in turn affected the steam turbines operation.
Solution: The turbine internals (rotor and blades) and turbine controls were designed to operate at lower loads with optimum efficiency and lesser maintenance. The steam turbine generator (STG) delivery happened at a record timeline of seven months, and erection and commissioning occurred within 35 days during pandemic conditions.
Benefits: The customer can now run the power plant in varied fuel conditions by overloading the STG set wherever possible.
With the inflating costs, efficient turbine operations have become necessary for saving costs and creating a positive carbon footprint. The turbine becomes inefficient and increases the cost of power generation after being in service for long. It becomes pertinent for the turbines manufacturer to actively engage with the customer to understand their current needs and work on re-designing the existing turbine across all brands to meet the new parameters, which can ensure efficient functioning of turbines and thus lead to cost savings.
Case study 2
A renowned customer was operating their 8 MW European OEM turbine for more than 15 years. The turbine was operating inefficiently due to natural degradation. A review of the turbine design revealed that by modifying the parameters as per the current requirements, it was possible to ensure the availability of 1 MW of extra power.
The proposed solution was based on the idea to direct the additional steam to the existing turbine with an upgraded steam flow path design. By simply altering the internal parts of the turbine (rotor with highly efficient blades, diaphragms, bearings and gear internals) with the new design, the customer was able to achieve an enhancement of 9 MW power with lower specific steam consumption than the normal running condition.
As the civil foundation was not altered, the overall project cost was significantly lower. Also, the turbine housing was retained. The turbine was commissioned and handed over with a 1 MW power addition and process stabilisation, the payback period was less than a year.
The benefits accrued by the customer through enhancing the efficiency of their existing turbine yield faster return on investment (ROI) and reduced operational expenditure (OPEX) requirement.
Bio-energy will become the prime source of fuel in the future. Biomass fuels help the CHP and cogeneration systems generate sustainable power. The global power generation industry must captivate the needs and requirements of both independent and captive power producers, as the demand for biomass power is stipulated to grow.
Contact Christo du Plooy, Triveni Turbines Africa, Phone 010 007-5245, mktg@triveniturbines.com
