Sunday, February 15, 2009

Energy from the dumpster downstairs


Massachusetts-based IST Energy has come up with an ingenious method of generating electric power from the daily waste. The Green Energy Machine (GEM) that the company developed does not look far from dumpsters commonly seen behind office buildings, including university buildings. However, instead of trucks collecting trash, the GEM offers the capability to turn trash into an energy source and use it to generate electric power.


Shown on the diagram, disposed trash goes into the GEM and passes through a waste conditioner where the trash is compacted, conditioned, and made into fuel pellets ready to be used in a gasifier. At the gasifier stage, the waste pellets are turned into syngas. (The benefit and effectiveness of gasification are not discussed in this post.) The final stage of the GEM is generating heat and electricity through the combustion of the waste pellets.

At a maximum waste processing capability of three tons, the GEM generates enough heat and electricity for a 200,000ft2 building. With a unit cost of $850,000 per machine, it is expected to have a payback period of three years or more due to savings from waste collection fees, lower energy bills with GEM-generated electricity, and tax credit. Environmentally, a reduction in waste product creates less landfill and the use of on-site dumpster / generator machine removes the necessity of waste transportation to the landfill.

Use of everyday trash regardless of their composition brings flexibility to the GEM because wherever there is a need for a commercial sized dumpster, it can be used and the user can reap the financial and environmental benefits.

I think the GEM is a viable idea and product which can be adopted into the UT campus-wide waste management system. With an increasing campus size and construction of more buildings, there is more demand for power and chilling stations. With the GEM system placed in the buildings that produce a large amount of daily waste such as Texas Union and dorms (especially), these buildings can become more self-sufficient in electricity while reducing the cost of waste removal along with food-rotting stink.

Sources:
[1] Turn trash into energy in your office parking lot
[2] IST Energy


6 comments:

perla.jennifer said...

This is similar to the “Cow/ Butterfly effect” post, where the methane from cow manure is converted in to electricity. It’s not clearly stated how much cow wasted is need to power 300 to 350 homes, but I think we have a winner in combing these two ideas. Both take into account daily wasted produce by both humans and animals, and converting it to a useful resource. I’m intrigued by the fact that wasted can be used to power our homes, which is a win-win situation since we will receive power and decrease waste.

You should check out the picture of the wasted pellets used as syngas,http://news.cnet.com/8301-11128_3-10140500-54.html, The picture remains me of rabbit food. It’s fascinating to see wasted reduced to these pellets and have it be useful.

I also noticed that this program could be beneficial to universities because it drastically can reduce the universities’ trash disposal fees. I’m curious to see if UT might consider this in the future.

Nate said...

This is a great idea, but I am hesitant to believe that all types of trash can be made into syngas. When plastics are present, how does this system deal with the emissions from burning a fuel pellet with plastic in it. I have been to a trash incineration facility in the past and the amount of environmental controls needed to scrub mercury, NOx's, SOx's, dioxin and other pollutants out of the emissions is massive and the most cost prohibitive aspect of incineration. At some point in this GEM system, the waste pellets will be burned for electricity generation, so my question is, how does it mitigate the pollution produced? Including the waste products left over after electricity generation? Its a good idea with some great potential, but I am not sold on its life cycle operations.

Mark McCarthy said...

I have to agree with Nate on this one. While it seems like a great idea, and may eventually become a standard method for disposing of waste, the issue of what gets put into it is a large one that will need to be overcome. The most obvious comparison that comes to mind is recycling bins... people put things in the wrong bin all the time. In this case, instead of being a slight annoyance, combusting the wrong materials would release a lot of toxins into the local air (imagine people throwing CFLs or PVC piping into it). It's a good start, but it will need either a very well controlled environment or a massive change in end user behavior to work at this time.

Michael E. Webber, Ph.D. said...

Waste=to-energy is a great way to go! And, these thermochemical pathways look particularly promising. But, environmentalists would probably raise concerns about air pollution, and consistency of the input stream is a challenge (a surmountable challenge, but a challenge nevertheless).

Jason C. said...

Interesting blog and article. One of the major concerns at a municipal solid waste (MSW) landfill is the relase of landfill gas (approx half methane half CO2 and trace of non-methane organic compounds) into the atmosphere that are produced from decomposition of solid waste. MSW landfills are the second largest human-generated source of methane emissions in U.S. which is not good as methane is a very potent greenhouse gas. By using the GEM to convert food, paper and wood into electricity on site, it will offset the amount of landfill gas produced at the landfill.
However, $850K is a steep capital investment for an unproven technology and I find it hard to believe it has a payback period of three years. I'm curious to know how much operating and maintenance costs are estimated per year. In addition, you would have to coordinate collecting trash from other buildings in the vicinity to feed it into the GEM which would require labor/equipment cost as well.

David Wogan said...

It's a very neat idea. I worry that toxic chemicals, batteries and plastics will make their way into the waste stream. One solution to this is require separate bins or containers for each type of waste: organic, recyclables, other, etc...

When I visited Korea a few years ago I noticed that you couldn't simply throw a plate of food into the trash can. You would scrape any leftover food into the organic waste bin, while the dirty plate would go into another bin. It seemed like a hassle at the time, but now it makes perfect sense to me. Getting this to work here is another story.