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There are around 250 rice mills[1] in Cambodia producing rice-based products. In remote areas without access to the electricity grid, mills are usually powered by diesel generators at a very high cost of the fuel. In areas where access to electricity grid is available, the cost of electricity is much lower than in the off-gird areas, but there are still margins to reduce the energy bill by using cheaper energy sources.

 

The rice husk waste produced in the milling process can be used as a fuel for gasifiers in order to produce syngas, which replaces diesel for electricity generation. Additionally, the biochar obtained as a byproduct of the gasification process can be used to improve the soil quality.

There are currently about 150 gasifiers installed nationwide, and it is foreseen that the number will increase up to 600 additional medium size (100-300 kW), and 50 large gasifiers (up to 1 MW)[2].

 

LESSONS LEARNT FROM THE EEP MEKONG PROJECT IN CAMBODIA

 

Implemented by the Cambodian Centre for Study and Development in Agriculture (CEDAC), the Improving Farmers’ Livelihood through Rice Value Chain project aimed to improve access to energy and the livelihood of rice farmers. With funding support from EEP Mekong between 2013 and 2016, the project developer procured and installed three gasification units at the rice mills in Prey Kambas and Bati districts of Takeo province, as well as in Kamcheay Mear district, Prey Veng province. The project was implemented in partnership with the Rice Mill Cooperatives established by CEDAC in these districts. Trainings on gasifier operation and basic maintenance were provided to selected cooperative committee members. The biochar produced from the gasification process is sold to farmers as a soil conditioner.

An analysis of the operation performance and economic indicators of the project provides a better understanding on under what conditions gasification is financially feasible. There are constant and variable factors that impact in the economic performance of the gasifier. The variable ones are those related with the volume of rice milled along the year (capacity factor), and are key to determine when a gasifier is feasible.

 

Constant factors impacting the economic performance of the gasifier (100kW):
  • Initial investment: 55,000 USD
  • Operation and Maintenance costs: 2,086 USD/Year
  • Cost of rice husk waste (fuel): 3 cents of USD/kWh
  • Cost of energy generation using diesel: 1 USD/kWh
  • Electricity grid tariff in Cambodia: 800 Riels/kWh (~20 cents of USD/kWh)

 

Variable factors impacting the economic performance of the gasifier:
  • Amount of rice milled per year (capacity factor): (Tn of rice / year)
  • Amount of diesel back-up required: (%) *This is also related to the Capacity Factor

 

The gasifier installed in Prey Kambas, with a capacity of 100 KW, is operating on a seasonal basis, based on the market demand of rice, and its production is estimated on 500 tons of rice milled per year. This amount is milled in just 625h per year, which is a very low utilization rate of the equipment (capacity factor[3]).

Such a low and intermittent use of the gasifier causes a higher demand of diesel to cover the periods while the gasifier is igniting. It is estimated that diesel accounts for around 17% of the total fuel used by the generator under this conditions, and the levelized cost of the electricity generated is 30 cents of USD per kWh; way above the grid tariff.

The levelized cost of the electricity is inversely proportional to the amount of rice milled per year. The break-even point where the cost of electricity is equal or lower than the grid tariff (20 cents of USD) is reached when the amount of rice milled exceeds 1,200 tons per year, and the diesel back-up covers less than 12% of the generator demand.

 

 
 
The green line in the figure shows the parity point where levelized cost of the electricity from the gasifier (blue line) and the price of the electricity from the grid (red line) are equal. For larger amounts of rice milled, the levelized cost decreases until it reaches its minimum at 3,000 Tons of rice per year.  
 
 

CONCLUSION

 
The utilization of rice husk to generate renewable energy through a gasification process, is only a feasible option for a utilization rate of the gasifier (Capacity factor) higher than 40% of its capacity, which is equivalent to milling at least 1,200Tn of rice per year. 
 
A lower utilization of the gasifiers, is not economically feasible and can’t pay back the investment within the lifespan of the project. Moreover, gasifiers performance is optimal only on a steady operation mode but not on an intermittent use for small quantities.  
 
The main factor negatively impacting the economies of the gasifier is the amount of diesel required to cover the periods while the gasifier is not fully operational. Small scale gasifiers with low utilization rates operate intermittently, and therefore require large amounts of diesel back-up: Over 20% of the energy used by rice mills (with gasification) that are milling below 1,000 Tn of rice per year, is generated with diesel.  
 
Thus, gasification is only feasible if the proportion of diesel used against the amount of rice husk is lower than 12-15%. This target is achieved only when the operation of the gasifier exceeds 1,200 Tn per year. 
 
Rice husk gasification in Cambodia has been traditionally based on donor funding due to significant market barriers in the sector. The main challenge for small farmers is the high upfront investment required. Other factors include lack of supporting policies (subsidies or Feed-in-Tariff), seasonal / intermittent supply of rice husk, and lack of access to financing from local banks. It was also found that farmers’ capacity to operate and maintain gasification units is limited.  
 
Based on the Rural Electrification Strategy of Cambodia, 70% of rural households will be electrified by 2030[4]. Thus, gasifiers to be installed within areas that are planned to be electrified will be competing with the grid, and must consider carefully the economies of scale described above. However, for the remaining remote areas not expected to be electrified within the lifespan of the rice mills, gasification will continue to be feasible due to the high cost of the alternative generation with diesel. 
 
In conclusion, gasification can be a feasible alternative to electricity from the grid only for rice mills with a high capacity factor and steady operation, but it is fully feasible in off-grid areas where diesel is the only option.
 
 

 


 

[3] The ratio of actual power generation installed against capacity. (http://en.openei.org/wiki/Definition:Capacity_factor)


 See more of project photos from Flickr Photostream

 

For more information, please contact EEP Mekong Regional Coordination Unit

Bernhard Meyhoefer
Programme Manager
Email: Bernhard.meyhofer (at) eepmekong.org 

Cosme de Arana
Business Support and Capacity Building Expert
Email: cosme.arana (at) eepmekong.org 

Website: www.eepmekong.org