COWS: Turning Garbage Into Gas
As populations grow, the amount of food waste, animal manure and agricultural waste will continue to exceed our capacity to build large treatment facilities. The waste-to-energy (WTE) market hit US$17.3 billion in 2011 and is expected to reach more than US$33 billion by 2022. Inspired by nature and perfected by NUS researchers, the Contained Organic Waste System (COWS) is intended to tackle the dramatic increase in organic waste production caused by urbanisation, industrialisation and growing populations. COWS turns household waste into household energy!
The NUS Environmental Research Institute (NERI) has developed a compact anaerobic digester that effectively converts organic waste into methane gas, which can be used to generate electricity and heat. What makes the COWS unique is its patented concentration system that allows homeowners to take their WTE conversion needs into their own hands and be less reliant upon the grid for energy needs. COWS’s by-product is digestate, and this can be used to produce fertiliser for agricultural needs. The COWS anaerobic digester is suitable for high solids organic waste, such as food waste or animal manure. The device has a proprietary three chamber design which separates the conversion process into discrete and contained stages.
The key innovation behind the NUS anaerobic digester revolves around its integrated three-stage process. Each stage is completed in a separate chamber (all contained within a single vessel) in order to optimise the specific reaction parameters, such as pH levels. The three stages are:
- Hydrolysis – this breaks down larger molecules into smaller molecules and an organic acid by-product.
- Acidification – this process commences the generation of methane gas
- Methane production – the third process fully converts organic acid into methane gas. Conventional anaerobic digesters typically only have two stages, skipping this final process which maximises production of methane.
Applications and Advantages
COWS has the potential to be applied throughout the WTE sector by organisations looking for improved waste management and energy recovery solutions. COWS can even scale up from the single family home to multi-unit apartment blocks and even businesses in the food processing, waste treatment and agricultural industries.
COWS demonstrates treatment efficiency for high solids organic waste. Studies have shown 20-35% improvement of methane generated, compared to digesters currently in the market today. Other advantages include:
- Improved organic loading rate, resulting in time savings;
- A streamlined design with reduced digester volume, resulting in a smaller footprint, savings in space and equipment cost;
- Reduced energy consumption.
NUS is seeking industry partners, to help commercialise this technology and scale up for larger yields.
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