In this blog post, I’ll explain in simple terms the scope of resource processing engineering and why waste and carbon dioxide reduction technologies are so important.

The Department of Energy and Resource Engineering: Expectations vs. Reality

When people hear the term “Department of Energy and Resource Engineering,” many immediately think of “renewable energy.” Many freshmen, myself included, often enroll with the expectation of tackling global warming and conducting research on renewable energy. However, in reality, the university curriculum and research areas are not significantly different from those of traditional resource engineering.
Energy and Resource Engineering encompasses various fields, including geophysical exploration, petroleum and gas engineering, rock mechanics, resource processing engineering, environmental geochemistry, environmental economics, and geological engineering. Among these, I will focus on resource processing engineering—a field that is often difficult to understand just by its name.

Areas Covered by Resource Processing Engineering

Resource processing engineering deals with the separation and refining of natural resources, the recovery of useful resources from waste, the safe disposal of waste, and carbon dioxide reduction technologies. Waste-related technologies have recently garnered more attention due to events such as the Fukushima nuclear accident, and carbon dioxide reduction technologies remain—and will continue to be—a critical issue due to global warming.

Recovering Resources from Waste

Recovering useful resources from waste refers to technologies that reuse materials that were previously discarded as resources. Examples include extracting methane gas from landfills, recovering methane gas from abandoned coal mines, and recycling by-product gases generated at steel mills. Due to environmental concerns, rising energy prices, and technological advancements, technologies that transform discarded materials into resources are becoming increasingly important.
Specifically, this process involves collecting landfill gas from landfills and by-product gas from steel mills, then using various separation techniques to isolate the gases that can be used as energy sources. The separation methods used include various physical and chemical techniques, such as gravitational settling, electrostatic separation using electrical polarization, centrifugal separation using centrifugal force, and the spray method.
Looking more closely at the recovery of methane gas from coal mines, methane gas is sometimes trapped in the voids between coal particles when coal seams are formed. In the past, this methane gas was a cause of mine explosions, but recently, methane is recovered by injecting compressed carbon dioxide into the voids, causing the carbon dioxide to enter and the methane to escape. This approach allows methane to be recycled as a resource while simultaneously achieving the effect of sequestering carbon dioxide underground, making it a two-for-one solution.

By-product Gas Recycling and Enhanced Oil and Gas Recovery

The recycling of by-product gases is a practical example of collecting and purifying gases emitted from industrial sites for use as an energy source. Furthermore, Enhanced Oil Recovery (EOR)—a method that involves injecting carbon dioxide into oil and gas reservoirs to increase the recovery of remaining oil or gas—is already a commercially utilized technology that allows for the simultaneous achievement of carbon dioxide storage and resource recovery.

Urban Mining: Rediscovering Electronic Waste

Urban mining is a concept that emerged in the 21st century, referring to the field of recovering precious and rare metals from electronic devices—such as cell phones, computers, and TVs—that we discard in our daily lives. Currently, the recycling of electronic waste is still insufficient, and in many cases, only a very small portion of precious metals, such as gold, is recovered.
However, considering the trend of increasing electronic device usage and shorter product lifespans, urban mining is an industry with great potential. By establishing a systematic collection and processing system and improving recyclability, it can grow into a market with significant economic and industrial promise.

Technologies for Preventing Waste Dispersal and Responding to Accidents

Since the Fukushima nuclear accident, interest in preventing the dispersal and managing radioactive waste has increased. When substances lethal to humans—such as radioactive materials, sulfur gas, and heavy metals—leak into the ground, technology is needed to predict their path of movement, assess the extent to which they have already spread, issue warnings of danger, and prevent further spread.
Such technology focuses on modeling the movement paths of contaminants and preventing accidents before they occur through real-time monitoring. The key lies in predicting the potential for dispersion by considering ground conditions, groundwater flow, and chemical reactions, and then devising appropriate remediation and containment measures.

Carbon Dioxide Reduction: Pre-Process Reduction and Post-Process Capture and Storage

Carbon dioxide reduction technologies are divided into approaches that reduce emissions before the process and those that capture and store carbon dioxide emitted after the process. Methods for reducing emissions before the process involve avoiding carbon-generating reactions whenever possible and using alternative mechanisms; however, these often face limitations in practical application.
In contrast, post-process reduction technologies consist of two stages: capture and storage. After the process is complete, a mixture of various gases is emitted; the separation technologies mentioned earlier are used to isolate and concentrate only the carbon dioxide from this mixture. The captured carbon dioxide is typically utilized in existing applications, such as EOR (Enhanced Oil Recovery), or stored under pressure in underground spaces such as limestone caverns or salt dome cavities.
Storing it under pressure above ground is also possible, but it poses significant challenges in terms of cost and land availability. In contrast, storing compressed gas in underground caverns eliminates the need for separate high-pressure containers, and the empty space can even contribute to ground stability. However, storage stability must be thoroughly evaluated. This is because if the stored carbon dioxide leaks and dissolves into groundwater or escapes back to the surface, the purpose of storage is lost. Therefore, projects must proceed after conducting a detailed investigation of ground conditions in collaboration with relevant fields such as geotechnical engineering.

Conclusion: Why We Should Focus on Resource Processing Engineering

Nearly a century has passed since the start of the Industrial Revolution, and humanity has consumed vast amounts of resources and degraded the environment in pursuit of convenience and capital accumulation. We now all recognize that waste from factories and households is causing global environmental problems, and it is clear that technological advancement must go hand in hand with solving these issues.
It is difficult to halt the Earth’s overheating—which is already accelerating—all at once. Instead, we need “cooling” technologies—that is, technologies that recover resources from waste, suppress pollution, and reduce and store carbon dioxide emissions. Now is the time to direct more attention and investment toward resource recovery engineering, which plays this vital role.