Edited by Kenneth Korane
Green engineering is the design and development of products and processes that bring environmental and economic benefits. That said, green engineering is fundamentally no different than any other type of engineering innovation. First, you need to get a handle on real-world behavior, which often entails measuring power consumption, emissions, and environmental factors such as temperature. Armed with the data, next you can improve efficiency or reduce environmental impact. On that front there is good news. Innovations in measurement, automation, and design tools have made the technology components for green engineering not only more accessible, but also easier to use.
Sometimes green engineering looks like plain old process optimization. When Nucor Steel acquired the Marion Steel Co. in 2005, one of its first actions was to add automation systems throughout the minimill. Melting and recasting steel demands a massive amount of electricity, so even small improvements in efficiency bring huge energy and economic savings. Nucor used programmable automation controllers (PACs) and NI LabView software to devise automation equipment that included a scale and weighing system, an online reactor in series with the furnace, and a remote switching station. This lets operators determine the exact amount of steel and, therefore, the exact amount of energy needed to heat the electric furnace.
Previously, the company had to estimate the quantity of steel in each burn. Results were hit or miss and sometimes the steel would overheat, waste electricity and, to make matters worse, cast steel with quality problems. The steel would then have to be reheated, consuming even more energy. Since implementing this weighing system, the company has drastically cut the number of reheats.
A significant portion of the work done for green purposes involves direct connections to ac-power lines. Fortunately instrumentation helps reduce the hazards of working with the potentially lethal voltages and currents. In wind turbines, for example, one of the biggest challenges is integrating the turbine with the electrical power grid. Occasionally, grid voltage dips and this traditionally causes wind turbines to trip out and stop sending power to the system.
It is now considered advantageous for wind turbines to stay online and ride out disturbances. But testing for this capability is a little tricky. Energy to Quality S.L., based in Madrid, Spain, has been testing wind farms for grid disturbance ride-through for the past two years. They use a mobile voltagedip generator controlled by an NI PXI data-acquisition system. The system measures secondary voltages at 110 Vac while controlling relays are connected to tripping coils. The hardware communicates results via TCP/IP to a remote computer safely away from lethal voltages. Tests take under a minute, so operators know immediately if the turbines comply with requirements.
All in all, designing eco-friendly products and technologies often begins with figuring out ways to measure the factors that put the green in green engineering.