Waste as Resource

The concept of landfill mining is not new. There has been little progress, however, since the first efforts in the 1950s. Reclaiming valuable materials from landfills has been the vision, with hope to reduce mining virgin resources, but economic viability has stymied landfill mining efforts. The dispersion and contamination of valuable materials found in landfills — metals, plastics, discarded electrical devices, and soils — have hampered making reclamation profitable.

Increasingly, the approach being applied is multifaceted, more than just resource recovery. The benefits of other strategies are: reducing pollution (air and groundwater); extending the life of landfills by reducing the volume of waste, or even regaining the land for other urban uses; lowering greenhouse-gas emissions (landfills are major emitters of methane); producing energy from waste; and creating green jobs. Since these additional benefits often exceed the value of removing valuable materials, taking a more comprehensive approach often changes the equation to profitability.

Costs connected to landfill mining vary widely. Projects that are not cost-effective in one location could be in another. Part of the difficulty in starting a project is understanding the composition of the waste and the concentration of the recoverable materials. Health and safety risks can be significant. Although mitigation measures can be taken, they increase costs, sometimes prohibitively. Costs will continue to decline, however, as the industry gains experience and as new equipment and techniques become available. For example, increasing excavator bucket size lowers cost.

Profits are starting to be made by converting waste into energy. Since 2014, a Belgian landfill project is generating 75 megawatts of electric power. Methane has been successfully captured from landfills for some time, preventing it from entering the atmosphere. But now, a relatively new plasma gasification technology is making it possible to transform refuse into hydrogen and a mineral residue that gets recycled into a green, low-carbon cement. Some European countries are offering renewable energy certification, redeemable in money, for these waste-to-energy and waste-to-fuels approaches. California will probably soon offer cap-N-trade monies to support such carbon-sequestering endeavors.

The Dutch teenager Boyan Slat, who developed an ocean-cleanup scheme, has now gone big time with his innovation. Although not a landfill, mankind has been using the ocean as a dump for decades. A complement to Slat’s capture of ocean waste is pyrolysis, a thermochemical process without oxygen capable of turning old plastic and synthetic rubber tires into fuel and biochar. The biochar can be safely stored in the ground or, when free of contaminants, used in farming to enrich the soil.

In Sweden, less than one percent of household waste ends up in the dump. Because it has been so successful in transforming its waste into resources, Sweden is now importing waste from other countries. It’s time California followed this same pathway.