Organic waste makes up 14% of total waste generated in the US. What if we could convert all that waste into something valuable - for instance, electricity, fuel, and fertilizer products - with 0% waste left in the end? Harvest Power, recently voted one of the Global Cleantech 100, does just that.
To simplify, Harvest Power's industrial-scale process consists of two majors steps: anaerobic digestion and advanced composting. The anaerobic digesters extract methane from the organic waste. This biogas is then processed to either produce electricity (by fueling a combined heat and power -CHP- unit), heating, and/or transportation fuel (by processing the biogas into compressed natural gas, CNG).
Just a bit of energy101 to understand why it's better for the environment to use organic waste as fuel than let it go to the landfill: On one hand, if the organic waste is left alone and sent to the landfill, methane from the waste is released into the atmosphere. Methane is a greenhouse gas that is 30-70x more potent than CO2 as a harmful greenhouse gas. On the other hand, anaerobic digestion allows to extract the methane and burn it as fuel. Of course, the combustion of methane will still release CO2 into the air, but it will be much less harmful than directly released methane.
After the anaerobic digestion, the remaining organic solids are aerobically composted using Harvest's proprietary Covered Aerated Static Pile system and processed into high quality soil, mulch, and organic fertilizers.
Advantages of Harvest's model? Reduce landfill needs (which I'm learning can be extremely costly), provide a much cleaner solution for the waste (by burning the methane instead of direct release), AND create value out of waste (electricity, fuel, and fertilizers!).
Totally awesome. I'm a tad bit concerned about the fact that the facilities are centralized and the waste and fuel must be distributed - potentially over long distances - and distribution can sometimes be the pitfall of a technology. But I trust that Harvest is working that out.
If you couldn't tell, I'm a huge fan of converting organic waste into energy. Check out Sanergy, The Park Spark Project, and Purpose Energy for other cool projects with the organic waste/scat=>fuel principle.