The commercial waste industry includes all those who collect waste from the simplest “collect waste and transport to a landfill” to the more complex “collect waste and process into re-usable components and energy.” This article will cover how we can collect material and fuel a clean energy system for our immediate future, while saving clean water and air.
Why Use Biomass?
Biomass refers to living and recently dead biological material—such as green, wood, biodegradeables and municipal solid waste (MSW)—that can be used as fuel to generate energy. Today, many States require 20 percent of generated power to be from renewable sources. Therefore, biomass is beneficial because most times it is the lower cost available fuel and can allow municipalities to provide heat and energy to nearby industrial/commercial users and their own facilities. Many biomass facilities can be tailored to the fuel stocks readily available in your region. Because multiple types of fuels can be used to produce energy, revenue sources from biomass can include tipping fees, electrical generation and recycling.
Types of Biomass Systems
There are four types of biomass systems: gasification (plasma technology and gasification from combustion process), incineration, solid fuel boilers and rotary cascading bed combustion (RCBC).
Gasification is a multi-step process using hightemperatures to convert biomass into a gas mixture that can be used for energy (see Figure 1). It is great for feedstock and product flexibility, emitting low emissions with high efficiency and it has energy security.
However, gasification is a complex multi-stage process with two-stage emissions control and an expensive initial setup because it includes several primary systems which are each complex in their own right:
- A gasification chamber with combustion cleaning
- Gas-air mix control and storage under pressure
- Gas combustion and heat use
With its accompanying multiple of components plus a pressurization system and pressurized containers, gasification is more costly, by multiples, than the simpler direct conversion RCBC system. In addition, upfront feedstock processing and pressurization is required as well as purifying the syngas (gas made synthetically rather than the natural variety).
A component of gasification is plasma, which uses high voltage arcs to break down waste into elemental gas and solid waste, resulting in syngas that can be used as fuel (see Figure 2, page 36). It is a very expensive technology using a complex, multi-stage process and requiring high maintenance. Plasma gasification does allow for recycling of large quantities of MSW and with the exceptionally high temperatures achievable.