German energy generation and engineering company AGO Energie + Anlagen and its South African subsidiary, AGO Energy, see potential for companies in South Africa to generate electricity through cogeneration or trigeneration, while using the excess thermal energy for heating or cooling purposes. Cogeneration and trigeneration are also environment friendly and save costs, says AGO CEO Hans-Ulrich Gruber.
While electricity in South Africa is significantly cheaper than electricity in Europe, the large increases in electricity tariffs for the next three years mean that there is now a more compelling business case for the development of cogeneration and trigeneration plants, he says.
AGO Energy specialises in developing electrical and thermal generation plants, from 1 MW to 16 MW or larger. Customers can use the thermal energy for heating or cooling processes, including the use of absorption chillers to produce subzero temperatures.
“We offer our energy solutions based on either fossil or renewable sources,” he adds.
The company developed a system for the Heineken brewery, in Sedibeng, with two 10-MW boilers that can run on natural gas, diesel or biogas, in 2009.
“Our interest lies in developing high-efficiency biomass plants for Europe and Africa. AGO is building Europe’s biggest wood-chip gasification plant that will deliver 5 MW of electrical energy and 7 MW of thermal energy. “This plant will save 40 000 t of carbon dioxide emissions a year,” he says.
In Italy, the company is developing plants that use steam turbines or organic Rankine-cycle turbines, where the 90 ºC hot water, gained from steam used to drive the turbines, is used to heat or cool other processes, which improves the efficiency of the process.
“The minimum size for a wood-chip gasification installation is between 4 MW and 5 MW electrical, because of the need for enough experienced staff to run the plant, which uses a combination of cogeneration in the engines and the organic Rankine process and improves the energy efficiency of the plant to 50% efficiency,” Gruber explains.
The exhaust air from such a process is expelled at around 400 ºC and is used to drive the turbines through steam generation. Water is used to cool the engines and this excess heat can be used efficiently in absorption chillers.
AGO Energy offers consulting services to assess a company’s carbon footprint and then presents the company with a number of ways to reduce this footprint, he adds.
“This analysis of the way companies use energy can present significant opportunities to reduce their energy dependence and environmental impact,” he says.
For South Africa, Gruber sees an opportunity to generate electricity and heating or cooling through the use of wood-chip gasification or combustion plants that will use biomass, such as invader plants, which are already being removed to save groundwater.
Further, companies that want to be more energy independent will benefit from the generation of electricity and 90 ºC hot water that can be used to heat or cool processes, he add.C
ompanies that do not use the hot water produced at over 90 ºC have the opportunity to use this wasted heat to generate subzero cooling without the need to produce more energy, he adds.
AGO Energy also predicts that natural gas will become more important as a fuel source in South Africa and Africa in the long term. This is due to the rise of electricity and oil-based product prices and the relatively stable price of natural gas, he says.