While decentralized sources of power, such as harnessing solar and wind energy to generate electricity, are well understood opportunities, there are additional fundamental areas where we are moving inexorably towards an infrastructure where being on the grid is an option, not a necessity. A recently announced new waste-to-energy system that turns trash into clean energy from IST Energy is an exciting example of this trend.
There are several credible companies developing ways to convert municipal solid waste (MSW) into energy, such as Ze-Gen, Plasco Energy Group, Rentech, Bluefire Ethanol, Coskata, Enerkem, and many others. But unlike these companies, which are developing technologies for centralized plants to convert thousands or, even more likely, millions of tons of MSW feedstock into electricity or fuel each year, IST Energy has developed a system that operates at an onsite scale.
If IST Energy’s technology moves out of the pilot phase – they are currently demonstrating a prototype unit for potential customers – the implications are huge. Instead of paying for expensive trash pickup and removal services, so waste can end up in a landfill, campuses, military bases, hospitals, and other institutions or commercial complexes can install a waste-to-energy solution from IST Energy, available in modules so it can be scaled to whatever waste processing requirement may apply.
During an interview last week with Stu Haber, CEO of IST Energy, he said the unit they are developing is 30′ by 8.5′ by 8′ high, able to fit in a standard shipping container for intermodal delivery anywhere. Into this volume, the system IST Energy has designed includes space for 3 tons of MSW storage at the front end (so it only has to be fed once per day), with a shredder, dryer, pelletizer, zero-emission gasifier, and internal combustion engine electricity generator that runs on the syngas extracted from the MSW.
|A cutaway view of IST Energy’s onsite waste-to-energy system.
(Image: IST Energy)
How much energy comes out of this system? A typical waste stream has somewhere between 8,500 and 12,000 BTUs of embodied energy per pound. With a gasifier that can extract up to 90% of this energy and convert it into syngas, and an internal combustion engine generator that converts the mechanical energy of the engine into electricity at about 27% efficiency, about 25% of every pound of waste input comes out the other end as electricity. Put another way, somewhere between 1-2 pounds of waste equals one kilowatt-hour, depending on the specific composition of the waste input. Additional energy is extracted in the form of heat, improving overall efficiency, and making these units miniature combined heat and power plants.
IST Energy intends to sell these units for about $850,000 each, meaning for that price you could process about 1,100 tons of waste each year, generating about 1.3 million kilowatt-hours, along with co-gen heat. At $.15 per kilowatt-hour, you would recover $200K per year just in electricity, plus you would harvest the heat, and presumably, save money on garbage collection fees (only about 5% of the volume of the waste material input remains as ash). If IST Energy can deliver this unit in large quantities according to these specifications, they have a very disruptive technology.