What is the most interesting thing about engineering?

One of my friend is working in the research department of a top FMCG group. His PhD was on flow of granular materials. I will list down couple of projects he has done.
(1) He worked on the problem of fluid flow through the diapers. According to him it is a very complex problem. In diapers, just like software, there are different versions. Each version is more soft and more comforting to the baby (he works in baby diaper segment). He has to take into account different viscosity, chemical nature etc. Sometime when he is stuck at some science problem, he collaborates with academia and floats PhD problems. Otherwise it is finding an optimal solution with existing tools. His specific is to develop a material given certain limitations and them minimize the cost of production
(2) He previously worked with a chemical company where he was involved in designing silos. There also, he used his knowledge of mass transfer to optimize the design under the constrains of failure condition.
(3) He worked on a process engineering problem where batteries were being manufactured and wastage was high per production cycle. He worked out, using again mass balance equations, optimum rate of input and output so as to minimize the wastage.

• Civil Engineering
  Civil engineering includes the design and construction of buildings, roads, bridges and dams. It is one of the oldest forms of engineering and involves further specialist areas such as transportation, water resources, surveying and construction.


• Mechanical Engineering
  Mechanical engineering deals with the application of mechanical power and the design of mechanical systems, machines and tools. Mechanical engineers require an understanding of a number of important principles including those related to heat transfer, energy, fluid mechanics and kinematics.


• Electrical Engineering
  Electrical engineering includes the study of electricity and the design of electrical systems like circuits and computer chips. Some of the areas electrical engineers might work in include telecommunications, electronics, signal processing and control systems.


• Chemical Engineering
  Chemical engineering uses science to process raw materials and chemicals into useful forms. Work by chemical engineers can lead to the discovery of important new materials and processes


• Aerospace Engineering
  Aerospace engineering involves the design and construction of planes and space shuttles. Aeronautical engineering covers craft that stay inside the Earth’s atmosphere (such as commercial planes) while astronautical engineering covers craft that leave the Earth’s atmosphere (such as space shuttles).


• Genetic Engineering
  Genetic engineering involves the manipulation of an organism’s genes. Genetic engineers directly alter genes using techniques such as molecular cloning and transformation.


• Computer Engineering
  Computer engineering combines computer science and electronic engineering in order to design computer technology from the very small, such as microprocessors, to the very big, such as supercomputers.


• Software Engineering
  Software engineering involves research, design and modification in order to implement fast, high quality software in a range of areas. Software engineers apply a variety of principles and techniques to computers and other products that use software.


• Environmental Engineering
  Environmental engineering applies various scientific principles and ideas to help provide clean water, minimize pollution and improve the environment. Environmental engineers work in a number of areas that can relate to air pollution, waste disposal, recycling, global warming, water pollution and other environmental issues.