Biomass (see What is Biomass?) is available in most parts of the world in plenty. And a good amount of it, in the form of crop waste and forest residues, is available at low costs for use for heating or for power generation.
Use of biomass (in the form of wood chips, small logs etc) for residential cooking is commonplace in many developing countries, especially in rural areas, and also in commercial establishments.
The industrial sector has also been using biomass in various forms for their heating purposes.
But besides heating, biomass can also be used as fuel to generate power. Given the fact that many industries have captive power generation systems (usually coal, diesel or natural gas based power plants), an interesting question arises: If biomass can be used to generate power, can these industries use biomass instead of coal (or diesel or natural gas) for power generation?
In some cases, this question becomes a lot more relevant.
A good number of industries – especially agro based industries – actually produce a good amount of waste biomass (saw dust, rice husk, oil cake…). These industries also require a significant amount of electricity to run their operations.
So, can the biomass waste generated by these industries be used for captive power generation for their own operations?
In a good number of cases, companies around the world have installed biomass based power plants for their captive power generation. Some of these are small power plants (as low as 50 kW) and some are as large as 10 MW or even higher.
To highlight, here are two examples (one from small scale and another from a large scale user) of how biomass can be used for captive electricity generation:
- One is rice mills. Rice mills need power to run their machinery and they also produce a waste product, rice husk. Combine the two and what do you get? Rice husk based biomass gasification power plants. Not surprisingly, many rice mills worldwide have installed captive power generation plants. From what I have seen, most of these rice mills require not more than 1 MW of power generation capacity. For this relatively low capacity, they use what are called biomass gasifiers, combined with a gas engine, to generate power.
- The second example is bagasse at sugar factories: Bagasse is a waste product generated from sugar factories/distilleries. For a long time, the bagasse was already being used by these sugar factories to generate heat for their processing requirements. Now, using the concept of combined heat and power that enables a sugar mill to generate also power in addition to heat, many sugar mills worldwide are using biomass for captive power generation. These units almost always use steam turbines to generate power, owing to their large scales.
From a recent discussion I had (in Aug 2016) with the head of biomass power for a large multinational company supplying biomass boilers, I understood that in many Asian countries (India, China…), there are significant supply chain challenges faced by large independent biomass based power producers. These challenges have to do mainly with volatility in prices of biomass, and in some cases, regular supply of biomass also pose challenges. Industries using biomass for captive power generation fortunately do not have to face these two challenges.