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Organic Rankine Cycle Cogeneration Plant of one-farm size using rice straw as single fuel

Periodic Reporting for period 1 - POWERICE (Organic Rankine Cycle Cogeneration Plant of one-farm size using rice straw as single fuel)

Reporting period: 2017-01-01 to 2017-03-31

Rice straw potential as fuel for energy production is currently undervalued. This worldwide abundant residue from agriculture is used for composting, livestock bedding or field burning. Field burning, which is the most common form of disposal due to the need for short turnaround time between crops, causes air pollution - CO2 and methane emissions (0.74 g/Kg straw d/w). There is a total lack of small-scale (< 1MWe) rice straw power plants operating efficiently in a one-farm basis, since: (1) its combustion yields ashes, very rich in silica (purity >75%), and causes slagging and fouling of furnaces at high temperature, and (2) In situ rice straw collection makes maintenance and operational costs very high.

POWERICE is the unique turn-key cogeneration plant designed for single rice farms, using rice straw as only source of fuel. While widening the potential market, this carries on a distributed energy production model, reducing the demand from the national grid, and reducing costs and wastes resulting from energy transportation.
The following work was performed:

Definition of an execution plan with the technical/operational conditions of the combined technology

Ensuring the freedom to operate analysis (FTO)

Study of the main features of rice farms around the world, to determine the most suitable areas for commercialisation

Study of silica market and financial approach considering silica withdrawal by POWERICE seller as a payment form

The results indicate that:

Rice straw ash has viable markets in POWERICE’s target markets.

The optimal solution is a 300 kWe type ORC unit (100kWe for Italy) recovering up to 710 kWth of thermal power from a boiler.

Several Nations were identified as a potential market, according to their specific rice growing model and public incentives for biomass energy

Silica can be used and valorised in exterior supply chains, thus allowing a lower equity and / or mortgage for the purchase of POWERICE
Our rice straw based technology can work efficiently (less than 1MWe) with low capital and operational costs. We have downscaled the biomass boiler to allow it to fit on a farm, implemented an innovative method that limits burning temperature.

Currently, Italy has about 2,500 farms, out of a total 4,000 in Europe. The USA market has about 7,500 farms. Europe has 8 significant rice producing countries including Italy, Spain, Greece, Portugal, France, Bulgaria, Romania and Hungary that produce a combined total of 3 million tonnes of rice per year on average.

Given that each hectare of rice crop has the potential to yield approximately 9.2 tonnes of rice straw, a farmer producing 100 ha of rice yields about 920 tonnes of rice straw. About 15% of burnt rice straw becomes ash, implying about 150 tonnes of rice straw ash from 100 ha that can act as a source of income in silica markets.