Products / Astillas
Biomass fuel that doesn't depend on the harvest.
Astillas is the Steamax biomass fuel made from cashew de-oiled shell, an industrial by-product. It has a high calorific value, ash below 3%, and small uniform pieces that feed automatically into your boiler or heater.
4,200 to 4,500
kcal/kg calorific value, higher than pellets, briquettes and rice husk
Below 3%
ash, against up to 20% in other biomass fuels
All year
steady supply, not tied to a harvest
30 to 50% lower
fuel cost than oil and gas
Six reasons plants choose Astillas
Most biomass fuels are farm residues, so their supply and quality follow the season. Astillas is different, and the difference shows up in your fuel bill, your ash pit and your stack.
No seasonal swings
Its main ingredient, cashew de-oiled shell, is an industrial by-product of cashew processing, not an agricultural residue tied to harvest. Supply and quality stay steady all year, so you are not caught out by a bad monsoon or a price spike.
High calorific value
4,200 to 4,500 kcal/kg, and 4,430 in a lab test. That is more heat per kilogram than pellets, briquettes or rice husk, so you move, store and burn less fuel for the same steam.
Ash below 3%
A lab test measured 2.16% ash. Ash starts to deform only at 1,248°C, well above normal furnace temperatures, which helps avoid clinker on the grate.
Helps hold particulate emissions down
Low ash means less fly ash in the flue gas. Sulphur is just 0.07% and nitrogen 0.35%, so SOx and NOx stay low too. With a bag filter, particulate matter stays below 50 mg/Nm³ on biomass.
Low ash disposal cost
Much less ash means fewer trips, less handling and a smaller disposal bill. The ash is rich in silica, about 44%, so it can be reused in industrial applications such as cement manufacturing.
Small size, automatic feeding
Small uniform pieces flow through hoppers and screw feeders, so Astillas suits automatic fuel feeding. That means no hand firing, steadier steam pressure and less labour.
How Astillas compares
Against other biomass fuels, and against coal, oil and gas. Fuel values are typical, and they vary by grade and supplier.
| Property |  Astillas |  Pellets |  Briquettes |  Rice husk |
|---|---|---|---|---|
| Calorific value | 4,200 to 4,500 kcal/kg | 3,800 to 4,200 kcal/kg | 3,000 to 4,000 kcal/kg | About 3,200 kcal/kg |
| Moisture | Below 10% | Below 10% | 10 to 20% | Below 10% |
| Ash | Below 3% (2.16% in our lab test) | Below 5% | 5 to 20% | About 18% |
| Made from | Cashew de-oiled shell, blended with sawdust and wood chips | Compressed wood or agro residue | Compressed agricultural residue | Rice milling residue |
| Supply through the year | Steady. The main ingredient is an industrial by-product. | Follows the supply of the residue it is made from | Follows the harvest | Follows the paddy harvest and milling season |
| Form and feeding | Small, uniform pieces that suit automatic feeding | Uniform pellets | Large blocks, often fed by hand | Light and bulky, so it needs more storage and handling |
| Property | Astillas | Coal | Furnace oil | Natural gas |
|---|---|---|---|---|
| Fuel cost per tonne of steam | Lower than oil and gas. Higher than coal. | The lowest of the four | Higher than Astillas | Higher than Astillas |
| Calorific value | 4,200 to 4,500 kcal/kg | 4,500 to 6,000 kcal/kg | 9,500 to 10,000 kcal/kg | 8,500 to 9,500 kcal/SCM |
| Ash | Below 3% | 10 to 30% | Almost none | None |
| Sulphur | 0.07% | 0.5 to 1% | 1 to 4% | Negligible |
| Fossil CO₂ | Near zero net | The highest | High | The lowest of the three |
| Price stability | Stable and predictable, not tied to oil or gas markets | Moves with domestic supply and imports | Moves with crude oil | Moves with global gas markets |
Straight talk: coal is cheaper than Astillas per tonne of steam. Choose Astillas over coal when you need less dust and ash, lower sulphur, a fossil-free fuel, automatic feeding, or where coal use is restricted.
What a tonne of steam costs on each fuel
Change any price to match what you pay, and the cost of a tonne of steam updates for every fuel. The example prices are only there to start you off.
FuelYour priceCost of a tonne of steam
Fossil fuels
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Biomass fuels
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Assumptions behind these numbers
One tonne of steam needs about 0.63 Gcal of heat. Fuel use is that heat divided by the boiler efficiency and the fuel's calorific value. Ash disposal is added on top for solid fuels.
| Fuel | Calorific value | Efficiency | Ash |
|---|---|---|---|
| Coal | 5,000 kcal per kg | 80% | About 20% |
| Furnace oil | 9,170 kcal per litre | 85% | None |
| Diesel (HSD) | 8,680 kcal per litre | 85% | None |
| Natural gas (PNG) | 8,600 kcal per SCM | 85% | None |
| Astillas | 4,430 kcal per kg | 75% | About 2.5% |
| Pellets | 4,000 kcal per kg | 75% | About 4% |
| Briquettes | 3,500 kcal per kg | 75% | About 12% |
| Rice husk | 3,200 kcal per kg | 75% | About 18% |
Calorific values are typical and efficiencies are indicative. Fossil CO₂ uses IPCC default factors, and biomass CO₂ is counted as zero. Prices vary by region and season, so use your own.
If you switch to Astillas
₹ 0
Enter your values
- Fossil CO₂ avoided
- 0 t a year
- Ash a month, today
- 0 t
- Ash a month, Astillas
- 0 t
How Astillas is made
Cashew processing leaves behind large volumes of shell. Astillas turns it into a controlled, consistent fuel.
1
Sourcing
Cashew shell comes from certified suppliers, so quality is set at the start.
2
Pre-processing
Contaminants are removed and the moisture level is monitored.
3
Oil extraction
Screw expelling removes the cashew nut shell liquid and brings oil content below 5%.
4
Acid reduction
Heat treatment lowers the anacardic acid content.
5
Blending
The de-oiled cake is blended with local biomass such as sawdust and wood chips.
6
Drying and sizing
The blend is dried and screened into uniform pieces.
7
Packing and storage
Packed for easy transport and a long shelf life.
What the lab says
A laboratory analysis of Astillas. Values are for the tested sample, and lot-to-lot results vary a little. A copy of the report is available on request.
Physical and heat value
Bulk density
0.5263 g/cc
Gross calorific value
4,430 kcal/kg
Proximate analysis
Inherent moisture
8.49%
Ash
2.16%
Volatile matter
72.75%
Fixed carbon
16.6%
Ultimate analysis
Carbon
42.25%
Hydrogen
6.09%
Nitrogen
0.35%
Sulphur
0.07%
Oxygen
40.37%
Ash fusion temperatures
Initial deformation
1,248°C
Softening
1,317°C
Hemispherical
1,336°C
Fusion
1,361°C
| Compound | Share of ash |
|---|---|
| Silica (SiO₂) | 43.84% |
| Calcium oxide (CaO) | 17.29% |
| Alumina (Al₂O₃) | 10.91% |
| Phosphorus (P₂O₅) | 10.6% |
| Magnesium oxide (MgO) | 8% |
| Iron oxide (Fe₂O₃) | 7.86% |
| Titanium dioxide (TiO₂) | 0.74% |
| Sodium oxide (Na₂O) | 0.5% |
| Potassium oxide (K₂O) | 0.25% |
| Sulphite (SO₃) | 0.01% |
What plants save on Astillas
Three published results from plants that switched.
52%
lower fuel cost
Pharma plant, Roorkee: LDO to Astillas
A boiler burning 25,000 kg of LDO a month at ₹60/kg (₹15 lakh) was converted with the OBR kit. It now burns 60,000 kg of Astillas at ₹12/kg (₹7.2 lakh), saving ₹93.6 lakh a year.
44%
lower fuel cost
Packaging plant, Kashipur: PNG to Astillas
A 10 lakh kcal/h thermic fluid heater burning 66,000 SCM of PNG a month at ₹50/SCM (₹33 lakh) now burns 154,000 kg of Astillas at ₹12/kg (₹18.48 lakh). That saves ₹14.52 lakh a month, or ₹1.74 crore a year.
15.8%
lower fuel cost
Food processing plant, Karnataka: briquettes to Astillas
A 6 lakh kcal/h thermic fluid heater fed briquettes by hand, 15 tonnes a month at ₹9.5/kg (₹1.425 lakh). With an auto fuel feeding kit and Astillas it burns 10 tonnes at ₹12/kg (₹1.2 lakh), saving ₹2.7 lakh a year. Astillas costs more per kilogram here, but the plant burns a third less and no longer feeds by hand.
Results depend on your fuel prices, boiler and load. Use the calculator above with your own numbers.
Steady supply, delivered across India
Steamax runs a logistics network that delivers Astillas in almost 22 states, so you get timely, hassle-free deliveries whichever plant you run.
Andhra Pradesh
Assam
Bihar
Chhattisgarh
Goa
Gujarat
Haryana
Himachal Pradesh
Jharkhand
Karnataka
Kerala
Madhya Pradesh
Maharashtra
Manipur
Punjab
Rajasthan
Sikkim
Tamil Nadu
Telangana
Uttar Pradesh
Uttarakhand
West Bengal
Scaling up in Goa. Steamax and the Goa Energy Development Agency (GEDA) have signed an MoU to set up advanced fuel processing units for Astillas in Goa, with planned capacities of 5,000 to 15,000 tonnes a month.
Buy the fuel, or buy the steam
Astillas can be all you buy from Steamax, or one part of a complete switch to biomass.
Buy Astillas as your fuel
Delivered to your plant for a boiler or thermic fluid heater that already runs on biomass. It pairs well with automatic fuel feeding.
How you pay
You buy the fuel as you need it. Add Steamax operations and ash disposal whenever you want them.
Convert to biomass, fuelled by Astillas
Steamax converts your oil or gas boiler or thermic fluid heater with the OBR kit, then keeps it running on Astillas. See the OBR kit.
A conversion costs 60 to 70% less than a new biomass boiler, or nothing upfront under BOOT.
Steam as a service, fuel included
Under BOOT we supply the Astillas, run the plant and dispose of the ash. You pay per tonne of steam or heat.
How you pay
No capital outlay. Fuel, operators, ash disposal and upkeep are inside the steam or heat price.
BOOT means build, own, operate, transfer. See all the ways to switch for how it works across conversion, new boilers and existing plants.
Questions about Astillas
Yes. Per tonne of steam, coal is cheaper. Astillas costs less than furnace oil, diesel and natural gas, typically 30 to 50% less. Choose it over coal when you need less dust and ash, lower sulphur, a fossil-free fuel, automatic feeding, or where coal use is restricted.
Cashew de-oiled shell, which is what is left after the oil is extracted from cashew nut shell, blended with local biomass such as sawdust and wood chips. It is dried and screened into uniform pieces.
Not with the seasons. Its main ingredient comes from cashew processing, an industrial activity, so it is not tied to a harvest the way rice husk and briquettes are. Moisture is monitored during processing, and Astillas is specified at 4,200 to 4,500 kcal/kg.
Astillas is made for biomass burners and retrofitted boilers, and it works with automatic fuel feeding systems. If your boiler or thermic fluid heater runs on oil, gas or coal today, the OBR kit converts it.
Very little. Ash was 2.16% in our lab test and stays below 3%, against 5 to 20% for briquettes and about 18% for rice husk. The ash is rich in silica, so it can be reused in industrial applications such as cement manufacturing.
Sulphur is 0.07% and nitrogen 0.35%, so SOx and NOx are much lower than with coal or other high-sulphur fuels. Low ash means less fly ash, and with a bag filter we hold particulate matter below 50 mg/Nm³ on biomass.
Standard greenhouse-gas accounting counts biomass as near zero net CO₂, because the carbon released was absorbed by plants only recently. Switching from coal, oil or gas therefore cuts your fossil CO₂.
Email info@steamaxindia.com with your location and how much you burn a month. We deliver in almost 22 states, and Astillas is packed for easy transport and a long shelf life.
Tell us about your boiler or heater. We'll price the Astillas.
Share its size, what it burns and where the plant is. We will come back with a price and delivery plan.
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