The modern civilization that originated from the Industrial Revolution is now spreading throughout the world. The demand for natural resources is rapidly increasing and the environmental problems are getting globally more and more serious. Our civilization seems hardly sustainable. What should we do to make it sustainable? This series establishes the fundamental theory of civilization, analyzes the problems of resources and the environment in terms of entropy, and suggests a solution to them.

Most of people believe that material recycling is the true recycling and thermal recycling is a fake. But the conventional material recycling is actually downcycling, whereas thermal recycling by the gasification system can realize more radical recycling. That is to say, what was thought to be the genuine recycling is deceptive, whereas what was thought to be the deceptive recycling is genuine. This recognition leads to reconsideration of the role that the government must play to promote recycling.

Georgescu-Roegen coined the fourth law of thermodynamics according to which matter continuously and irrevocably degrades from an available to an unavailable state in a closed system including the Earth and predicted that we would soon arrive at the state of maximum entropy, material death rather than heat death. He also insisted that recycling could not avoid this material death, because the ideal of complete recycling is based on the illusion of the thermodynamically impossible perpetual motion. But what he called the fourth law of thermodynamics is false. A closed system such as the Earth can reduce material entropy in exchange for increasing thermal entropy, keeping the former low by dumping the latter in outer space. That is to say, a sustainable economy based on recycling is possible, at least theoretically.

As Our Common Future insisted in 1987, “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” Since the Industrial Revolution, human development has accelerated so much that its sustainability has come into question. Here I would like to present my proposal for what we should do to make our civilization sustainable. There are three major problems, namely the restriction of population growth, the maintenance and restoration of vegetation, and the utilization of renewable energy.

How long can our civilization flourish? Will our civilization remain thousands of years hence? During the Cold War the greatest threat to humans was nuclear annihilation, but today it is the environmental problem. Many people are afraid that global warming might collapse our civilization. In 1997, COP3 adopted the Kyoto Protocol to reduce greenhouse gas emissions, but the U.S. and Australia have declined to ratify the agreement. It has turned out a failure. On this page, I analyze the problems of the Kyoto Protocol and propose an alternative feasible framework that reduces greenhouse gasses.

Fuel cells were invented in the 19th century, but their practical application has been extremely limited to date, as thermal power generation has become the mainstream method of power generation. Today, with decarbonization and the hydrogen economy, fuel cells are again attracting attention as a method of power generation using hydrogen. Innovations are necessary for fuel cells to become more practical than they are today, not only in the fuel cells themselves but also in the way of storing and transporting their fuel, as well as in the method of producing it.

About one-third of the world's land surface is arid or semi-arid. The Earth's landmasses are losing 24 billion tons of topsoil and making 12 million hectares of the Earth useless for cultivation every year. The desertification is, however, not necessarily anthropogenic. So, first, we must elucidate what are the natural conditions of the desert. Then we can identify what are the artificial causes of desertification.

Today, mainstream scientists recognize global warming as a challenge for our civilization, while skepticism persists. There are various types of skepticism, but we can classify them into three categories: skepticism about the trend of global warming, its anthropogenic causes, and the assessments of its impacts. Here, I would like to examine these three issues about global warming: facts, causes, and assessments. I will then consider how we should deal with global warming.

Although we intuitively understand what pollution is, its essence is unclear. Without gaining an insight into the concept of pollution, we cannot find a solution to eliminate it. In this article, I first define what pollution is in terms of entropy and then examine the feasibility of material recycling and energy recovery of waste as the solution for waste disposal.

Oil and coal, which have brought about modern industry, are limited resources and destined to be exhausted someday. Moreover, combustion of oil or coal causes various kind of pollution. That's why the advanced nations are groping for the clean alternative energy sources since the oil crisis. There are many candidates for it, such as nuclear power, photovoltaic power, wind power, waterpower generation, but it is my considered opinion that methane is the best alternative energy sources. I'll tell you the reason for it.