At full capacity, approximately 4,000 inverters are produced each day at SMA’s solar inverter factory in North Hesse, Germany. In operation since March 2009, the plant is the largest solar inverter factory in the world, with a production area of approximately 18,000 square metres, and an annual production capacity of up to 4 gigawatts.
Motivated by the desire to lead the way toward carbon neutral manufacturing, SMA partnered with the Distributed Energy Technologies Competence Network (Kompetenznetzwerk Dezentrale Energietechnologien or deENet) at the University of Kassel, and Seeger Engineering AG to develop a method that would enable companies to achieve a CO2 neutral production.
“The new SMA inverter factory is the flagship building for this method,” explains Günther Cramer, Chief Executive Officer of SMA Solar Technology AG.
Mr Cramer considers that, because the company is a leader in the industry from a technological and ecological standpoint, it bears a certain responsibility to contribute to the wider effort in tackling climate change.
“This carbon neutral factory project makes it clear that industry can play a major role in making the national climate protection strategy a reality.”
Mr Cramer says that the most innovative companies already consider climate protection an indispensable component of their corporate management and are implementing these measures to increase their competitive edge.
Implementing a carbon neutral production process
SMA’s strategy to achieve carbon neutrality involves reducing energy demand, sourcing energy from renewable and low emissions sources, and then, offsetting all unavoidable carbon emissions.
Emissions are reduced through internal efficiency measures in the production process and the building design (which meets the requirements of the German low energy building standard), including a combination of optimal natural lighting and smart ventilation systems that reduce energy consumption in the production and testing facilities.
The energy concept couples different energy sources to provide heating, cooling, compressed air, and electricity for a whole host of tasks in the industrial production process.
Electricity
The electricity from a building-integrated, 1.1 megawatt photovoltaic system is fed directly into the public power grid, positively impacting the factory’s carbon footprint. In addition to heat, the internal, biogas-fired combined heat and power plant also generates carbon neutral electricity.
Green electricity purchased from the local utility rounds out the energy supply needed to meet the demands of production. Eventually, SMA plans for the entire carbon footprint of the factory – including the green electricity portion – to be offset with renewable energy supplied exclusively from regional sources.
Heating
The biogas-fired heat and power plant produces the base load to heat the factory; the rest is piped in from the district heating and power station located at the neighbouring garbage incineration plant, and therefore also originates from a combined heat and power plant.
The third source of heat is the electric compressor, which provides compressed air for various tools and hoisting gear; all of its waste heat is fed back into the heat distribution system. The backup condensing boiler only takes over when the combined heat and power plant is being serviced. Each of these heat sources is connected to a reservoir, which helps handle peaks in production and consumption and allows for continuous use of the heat.
Cooling
Two methods are used for cooling: an absorption refrigeration system utilises the continuous supply of heat from the combined heat and power plant to cool the facility. The compression refrigeration system, by contrast, runs on electricity and works just like a commercial air conditioning unit. This system is only used when additional cooling is needed. A reservoir in the cooling system also smoothes out peaks in production and consumption and ensures adequate cooling at all times.
Compressed air
Compressed air is a simple, safe, robust source of power for driving tools and hoisting gear in an industrial environment. To generate compressed air, a compressor needs electricity and ambient air. The heat generated during this process is also utilised as it is channelled into the heat reservoir.
Monitoring progress
“Since the planned measures were implemented, we have been closely monitoring our CO2 emission on a continuous basis,” says Mr Cramer.
In co-operation with deENet, SMA monitors all material and energy flows throughout the entire lifecycle of the manufactured products, including upstream chains, in the factory, and during their useful life.
“We therefore need information from the purchasing department, the production department, and the sales department of a company in order to form an accurate assessment of total emissions. Of course, we also want to document and implement any potential for improvement,” says Mr Cramer.
“The inverters, being the heart of every photovoltaic system, already significantly contribute to an emission-free energy supply. With our carbon neutral inverter production we go even one step further. Today we can show that advanced production on an industrial level can be done with a minimal environmental footprint.”
