How can agricultural waste provide sustainable materials and energy?

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The world generates millions of tons of agricultural waste every day. A country like India alone generates over a million tons of agricultural waste a day.

A large portion of the agricultural waste is not utilized productively. Worse, a good portion of the waste is actually burnt at the fields, releasing CO2 without any attendant benefits. Adding more misery, such farm based burning, in many cases incomplete, could emit significant amounts of dioxins, a toxic pollutant. In fact, a 2014 Canadian study mentions that, “It has been found in Taiwan, for example, that during the week of the most intense agricultural burning, the concentration of dioxins in the atmosphere is up to 17 times higher than in weeks when such burning is absent.

Surely human ingenuity can turn such crop waste into something far less harmful and far more useful?

Not surprisingly, the answer is a big yes.

Agricultural/crop waste can be converted into one or more of the following “energy products”, using a variety of technologies:

  • Biochar/charcoal – These can be used as fuel, or for making valuable substances such as activated carbon. The more woody crop waste – coconut shells for instance – the better they are suited for charcoal making. Charcoal commands a good price in many markets, so this route indeed presents an attractive business case. (See How is Charcoal Made from Biomass?)
  • Power generation for commercial and industrial units – Using a variety of technology routes, crop waste can generate power from very small scale (10 kW) to large scale power plants with tens of MWs! A wide range of agricultural and farm waste can be used for this. I have seen biomass ranging from rice husk, saw dust, stalks of a variety of plants, paddy straw, bagasse, coconut pith and even sugarcane trash used for power generation. See here, here and here for more on this.
  • Commercial and industrial heating – Almost every crop or farm waste can be used for industrial heating purposes – in boilers and hot air generators, in cook stoves, ovens and other small appliances. While some of these – especially for some types of boilers – can be in their loose form, many other appliances will need these crop waste in the form of briquettes or pellets (these are forms of compacted biomass – more on briquettes and pellets here).
  • Biofuels such as biodiesel or ethanol can be produced from crop waste.  While crop waste rich in starch or cellulose (think waste from sugar cane, potato, corn…) can be used to make ethanol (a substitute for gasoline), crop waste rich in lipids (well, this list is more select – think unproductive oil seeds such as jatropha, and also certain types of microalgae) can be used to make biodiesel, a direct substitute for diesel. See also: Can I make biofuels from agricultural waste?

The above crop-waste-to-energy avenues are already established sectors with mostly mature technologies.

In addition, a number of interesting non-energy avenues are also emerging as end product ideas for crop waste. These include:

  • Crop waste to plastic substitutes – examples include food plates, cutlery and related products made from crop waste such as rice husk and bagasse. (Some basic questions answered on sugarcane bagasse based plates and cutlery).
  • Bioplastics and polymers – currently, most starting raw materials for these are still food based starch products (such as corn and sugarcane), but increasingly, companies are figuring out ways to have crop waste as the starting point. (For more, read: Can we use plants to make plastics?)
  • Other sustainable household materials – an emerging area is wood plastic composites, where crop waste based fibers or biomass is used along with plastic to make an end product that contains less of plastic and more of renewable materials.

Thus, with just a bit of foresight and investments, a good portion of the agriculture waste can be converted into something of value. This is a win-win for everyone – for the farmers (as they can monetize the waste), for the industry (they now have cheaper feed stock), and the environment!

When I visit a number of rural areas (especially in India) as part of my work in my consulting or research work, I come across farmers burning agri waste because they need to clear that space and they have no other methods of disposal. When I tell them about the alternative uses of such waste which could also provide them with some decent cash, they feel that a lack of an organized collection and logistics of their waste is the main bottleneck in such monetization. This bottleneck is even more prominent for villages that are farther away from industrial areas that need the waste. I do not have a ready answer, but here surely is an opportunity for entrepreneurs to think up a business model that can make a difference and make money!

How can agricultural waste provide sustainable materials and energy? - Cleantech Guide

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