A few weeks back, I had the opportunity to meet up with some interesting engineers at IIT Mumbai. But these engineers were entrepreneurs too, and they have set up a bio-energy technology company named Urjas Gasifiers.
Urjas, based out of the business incubation cell at IIT Mumbai, specialises in biomass gasifiers.
Put simplistically, biomass gasification is the process in which the biomass (wood chips, coconut shells, rice husk, groundnut shells and even saw dust) is converted into an organic mixture of gases, called the Producer Gas. This gas can in turn be used for heating (in a furnace or a boiler) or for power generation through its use in gas engines (these are similar to diesel gensets, except they can use producer gas as fuel instead of diesel).
A typical biomass gasification system illustration
Making the Case for Biomass Gasification ( instead of direct combustion)
You might wonder why someone would wish to undergo the gasification route, as it appears more complex than direct combustion of biomass.
The following are some of the reasons
1. In many cases, the use of gas for heating results in better efficiencies than direct combustion of biomass, as gas-based flame is more controllable than solid fuel based burning
2. In cases where you need a cleaner fuel, once again use of gas is superior to use of solid fuels, as it is possible to clean the gas before it is sent to the burner
3. In cases where power generation on small and small-medium scales (sub 1 MW) is the desired end result, producer gas comes up trumps over solid burning again as it can be used in small scale gas based gensets for power generation, while it is mighty difficult to operate rankine cycle based power generation for scales less than 3 MW.
[And, Pradeep Podal for Urjas Energy sent me an interesting pic that shows how a gasifier allows for an way to retrofit over other traditional solutions. I guess this is possible mainly of the fact that the fuel we get is a gas which can be controlled pretty niftily. Here’s the picture]
So, let’s say I have been able to convinced you that the gasification route has distinct advantages over the direct combustion of solid biomass, for both biomass heating and biomass power generation.
The (More Powerful) Business Case for Biomass-based Heating
I however need not try so hard to convince you on the business case for biomass-based heating per se – all you need to do is to refer to this post of mine that lays out the economic case for the use of biomass in lieu of fossil fuels such as furnace oil, LPG or diesel. There can be savings of an impressive 40% to an awesome 70% when you shift from fossil fuels to biomass for heating today.
You can now see where gasifiers fit – they have a sweet spot in the small and medium heat generating industries; this comprises companies that use perhaps a few thousand liters or Kgs of furnace oil, LPG or natural gas every day; especially LPG or natural gas, as they can now replace fossil fuel based costly gas with bio-based producer gas that costs much less.
If biomass heating has so many benefits, and if gasifiers present significant advantages over direct combustion, why isn’t every commercial unit that currently uses fossil fuels for heating standing in a long queue to purchase biomass gasifiers?
This is because biomass gasifiers present technical and operational challenges, some of which are unique to them.
Challenges with Biomass Gasification
1. One problem that has been often reported is maintenance issues. In fact, if you talk to anyone in the solid fuel based hot air generators or those making boilers, you will hear how boilers are absolutely trouble free and to a certain extent, even solid fuel hot air generators too are. But they will spend enough time telling you stories of how biomass gasifiers have the potential to make your life more than a bit uncomfortable with the amount of maintenance that they demand.
2. Inflexibility of fuel options – Another issue that has plagues gasifiers is that these are usually designed for specific types of biomass or coal. Changing the feedstock can have significant adverse effects on efficiencies and operations. And uh oh, biomass comes in all types of types and forms, from woody coconut shells to moist bagasse – you get it!
3. Continuous operations – In theory, one can store producer gas, but in practice I have not seen anyone do it, so it most likely doesn’t make economic sense. This implies that gasifiers are configured for continuous operation. Thus, if you need to slow down or stop the heating in the middle of the burning, you are out of luck, and you simply have to let off that producer gas (and loads of money) as waste.
Jeevan Gasifiers from Urjas Energy Solutions
What impressed me about the gasifiers from Urjas, a company that has been incubated at the labs at IIT Bombay, was that they were attempting to solve each of the above three challenges in a significant manner
Maintenance – On maintenance, due to a special improved design in the Jeevan gasifier, much less clinker and tar formation results, and an effective and proprietary gas cleaning system ensures that their gasifiers have relatively low maintenance. While ash formation is much less of a problem from a pollution control point of view, tar is a different story. Disposing tar is not easy, and even the phenolic water that results from wet scrubbing of the producer gas can be a headache for the gasifier operator. By reducing the amount of tar formation, this gasifier could result in far fewer pollution control problems.
On fuel flexibility, Urjas gasifiers are Multi Fuel gasifiers, and can use over 7 different types of biomass, including loose bagasse. And for those who have to turn to coal now and then, these gasifiers can also use lignite coal. I think this could be a significant benefit especially to small-medium units for whom it is difficult to secure continuous and reliable supply of biomass, as prominent and organized biomass suppliers might not be interested in catering to this segment. Thus, the ability to use multiple biomass feedstock, and even coal if needed, could come as a much needed feature for these sectors.
On the need for continuous biomass use as well, the Urjas guys seem to have done something really nifty. As mentioned earlier, gasifiers cannot be turned off suddenly. The only way to instantly reduce their output is to flush the gas from the system to a flare. However, this leads to unnecessary wastage of fuel. The Urjas folks have developed a control system which greatly reduces this wastage. Urjas gasifiers have a turn down ratio of 1/3, and this is clubbed with a smart customized control to make sure that rapid ramp down is rarely needed. This results in significant savings on fuel and improving efficiency. Depending on the application, this could on an average improve the system efficiency by 15% or more, according to the folks from Urjas.
Urjas proprietary Vortex burner in action. The special design allows for high flame efficiencies (Source: Urjas web site)
I was quite impressed by the fact that the team had thought through some of the challenges and had put in serious efforts to overcome them. I am sure it is early days for the young Urjas team, but I am confident that they can have a good shot at making it big in select market segments. Here’s wishing them the very best!
To know more about the Urjas Jeevan gasifiers, check out their Urjas web site
Some useful links
100s of Solar Questions Answered @ Ask Solar Mango - Read More