Waste Gasification: How Old Technology Can Solve a Modern Problem

Over the next 30 years, global waste generation is predicted to grow to over 3.7 billion tons per year, a 70% increase over the current annual rate. The next 30 years are also set to be a critical time for the clean energy transition as nations push to cut carbon emissions and mitigate the extent of global climate change. With these challenges looming, waste-to-energy (WTE) technologies such as incineration have become a popular option for addressing both issues.

Despite incineration’s growing popularity in many parts of the world, it is also infamous among environmentalists for releasing harmful pollutants into the atmosphere. The solution to this may lie in an old technology that is being repurposed for this modern challenge: gasification.

While incinerators burn trash and use the heat to generate electricity, gasification involves no combustion. Waste gasification is a chemical process where trash is heated in a low-oxygen environment to the point that it breaks down into its constituent molecules. This reaction has two products: a combustible gas called syngas and inert slag or char. Depending on how it is processed, syngas can be used directly for electricity generation, or it can be refined into a variety of valuable products including diesel, hydrogen, and useful chemicals.

The option of refining syngas into synthetic fuels that can power internal combustion engines makes gasification a far more flexible WTE solution than incineration, which is limited to producing electricity and heat. Gasification is also the more efficient option for electricity generation. While conventional incinerators can net about 530 kWh of electricity from one ton of waste, gasification systems with integrated generation can net between 650 and 1,000 kWh from the same amount of trash. Syngas can also be cleaned of contaminants pre-combustion, making it safer for the environment than incineration with post-combustion emissions controls.

With this potential in mind, several companies have tried to enter the waste gasification market with mixed results. A standout in the field is Sierra Energy, a California-based waste gasification firm that has garnered tremendous support for its FastOx gasification system, which they claim can turn almost any waste stream into 90% syngas by using extremely high temperatures and an efficient design based on blast furnaces. While the system is still unproven at scale, the company’s first commercial FastOx facility was recently completed at Fort Hunter Liggett, which will serve as a proving ground for the technology’s long-term viability.

Even with these promising advancements, waste gasification faces challenges that it will have to overcome. For one, electricity generated from syngas will have to compete with the already low price of natural gas. No company understands this better than Plasco Conversion Technologies, which has transitioned to selling its technology to municipalities after their gasification WTE project failed to compete with natural gas in the electricity market. Even more daunting is the sheer risk of entering a relatively new sector with technology that still needs to be perfected at scale.

Despite these hurdles, there is good news for the economics of waste gasification. As landfill space becomes scarce around major cities, disposal and transportation costs will increase and make waste gasification a relatively cheaper source of energy. The flexibility of gasification also helps it here, as the products that syngas is refined into can be tailored to whatever is most profitable in local markets. In the future, waste gasification projects will likely also benefit from renewable energy subsidies and carbon credits based on the methane and fossil fuel emissions they offset.

While this technology still needs to be proven at scale, waste gasification has the potential to be a promising component of the future WTE and clean energy landscapes.

Matthew Fouts

Undergraduate Seminar Fellow

Matthew Fouts is an undergraduate student studying psychology and earth science at the College of Arts and Sciences. Fouts was also a Kleinman Center 2020 Undergraduate Student Fellow.