Solar bubble drier: Inflatable solar dryer for crop drying

Low-cost hygienic drying technology for high-quality products

The ISD (Solar Bubble Dryer) technology is a mobile drying system that dehydrates freshly harvested cassava roots in a protected environment using solar energy. It operates by harnessing solar energy through two main mechanisms. First, the drying tunnel acts as a solar collector, with sunlight entering through a transparent top and converting into heat to raise the air temperature, speeding up the drying process. Second, a photovoltaic system—consisting of a solar panel, rechargeable battery, and controller—generates electricity to power a small blower, which circulates air through the drying tunnel, inflates it, and removes moisture from the cassava. This system also allows product mixing without opening the tunnel, using either a roller on ropes beneath the tunnel or an internal rake.

This technology is pre-validated.

9•9

Scaling readiness: idea maturity 9/9; level of use 9/9

Adults 18 and over: Positive high

It enhances productivity by reducing post-harvest losses and improving the quality of produce. This can lead to higher income and improved livelihoods.

The poor: Positive medium

While the initial cost may be a barrier, the long-term savings from reduced losses and increased market access can help offset the investment, making the technology a cost-effective solution for poor farmers in the long run.

Under 18: No impact

Women: Positive high

It reduces their workload, allowing women to focus on other income-generating activities. It also provides an opportunity to increase the quality and quantity of dried cassava, leading to higher market value and potentially better income.

Climate adaptability: Highly adaptable

It utilizes solar energy, a renewable resource, for drying cassava, which makes it adaptable to changing climate conditions.

Farmer climate change readiness: Moderate improvement

It can improve the stability of yields by enabling timely post-harvest processing, which is critical for maintaining food supplies in the face of changing weather patterns.

Biodiversity: Positive impact on biodiversity

By minimizing chemical pesticide use (since the technology reduces the need for pest control), it contributes to preserving beneficial insects and organisms in the ecosystem.

Carbon footprint: Much less carbon released

It produces no emissions during operation, helping to reduce the overall environmental impact of drying processes.

Environmental health: Greatly improves environmental health

It promotes cleaner, healthier processing. It prevents the contamination of food and the surrounding environment, thus contributing to better overall environmental health.

Water use: A bit less water used

It can contribute indirectly to water conservation by reducing the need for overuse of water for crop processing or the washing of food.

Soil quality: Not yet estimated

Problem

Perishability of Fresh Cassava: Cassava roots deteriorate quickly after harvest, causing substantial post-harvest losses.
Unsuitable Traditional Drying Methods: Open-air drying exposes the product to weather, insects, dust, and animals, reducing product quality.
High Transportation Costs: Cassava’s high moisture content makes it uneconomical to transport fresh, highlighting the need for drying near harvest sites.
Degradation of Starch Quality: Delayed processing affects the purity and functionality of extracted starch.

Solution

Faster Drying and Improved Quality: Drying occurs in a closed, protected environment, enhancing product quality.
Mobility and Proximity to Harvest Sites: The mobile technology enables drying near harvest locations, reducing transport costs and post-harvest losses.
Energy Independence: Solar-powered and self-sustained, it does not require fuel or electrical grid connections.
Hygiene and Protection: The product is protected from rain, dust, insects, and pests, ensuring a cleaner, higher-quality output.
Reduced Post-Harvest Losses: The technology minimizes cassava losses, which are typically between 28% and 42%, through quicker, more efficient drying.

Key points to design your program

The Solar Bubble Dryer (ISD) technology addresses key challenges in post-harvest processing, such as crop spoilage and inefficient drying methods. By utilizing solar energy, it offers an efficient, environmentally friendly solution that reduces post-harvest losses and improves food quality. The technology supports the Sustainable Development Goals (SDGs) by promoting food security (SDG 2), providing sustainable solutions for rural communities (SDG 7), and enhancing environmental sustainability (SDG 13) through its use of renewable energy.

This innovation helps farmers dry crops faster, preserves the nutritional value, and increases shelf life, making it ideal for development programs aimed at improving food security and boosting farmers' incomes. It works well in conjunction with other agricultural technologies, providing a holistic approach to improving post-harvest management, reducing waste, and enhancing the economic opportunities of rural communities. Technical support from partners like local agricultural extension services ensures successful implementation and sustainability.

Cost: $$$ 1,800 USD

Initial investment

ROI: $$$ 7 - 180 %

Benefit for Cassava

90 - 145 kg of cassava per 3-5 day cycle

Drying Capacity

10 years

Lifespan

10,957 - 29,604 USD

Operating Costs

IP

No formal IP rights

Countries with a green colour: Tested & adopted
Countries with a bright green colour: Adopted
Countries with a yellow colour: Tested
Countries with a blue colour: Testing ongoing

Countries where the technology is being tested or has been tested and adopted
Country	Testing ongoing	Tested	Adopted
Cameroon	–No ongoing testing	Tested	Adopted
Democratic Republic of the Congo	–No ongoing testing	Tested	Adopted

This technology can be used in the colored agro-ecological zones. Any zones shown in white are not suitable for this technology.

Agro-ecological zones where this technology can be used
AEZ	Subtropic - warm	Subtropic - cool	Tropic - warm	Tropic - cool
Arid
Semiarid
Subhumid
Humid

Source: HarvestChoice/IFPRI 2009

The United Nations Sustainable Development Goals that are applicable to this technology.

Goal 2: zero hunger

By enabling farmers to dry their produce quickly and effectively in a protected environment, it helps ensure that food is available for consumption or sale, improving both quantity and quality.

Goal 5: gender equality

By adopting the ISD technology, women can significantly improve their productivity, increase their income, and reduce the labor-intensive nature of food processing.

Goal 7: affordable and clean energy

The ISD technology uses solar energy, a clean and renewable source of power. This supports the goal of providing access to affordable and clean energy for all, especially in rural areas where access to electricity or other energy sources might be limited.

Goal 12: responsible production and consumption

It helps minimize the need for chemical treatments or excessive use of water, which are often associated with traditional drying methods.

Goal 13: climate action

The use of solar power for drying reduces the carbon footprint of the food drying process, contributing to climate change mitigation.

To use the ISD (Solar Bubble Dryer) technology effectively, follow these steps:

Set Up the Dryer Near the Harvest Site
Place the Solar Bubble Dryer close to where the cassava (or other perishable crops) is harvested to minimize transportation costs and reduce post-harvest losses. Ensure the setup area is flat and free from debris for stability and optimal airflow.
Load the Fresh Cassava
Spread the freshly harvested cassava roots evenly within the drying tunnel. This ensures even exposure to the drying air, promoting consistent dehydration. Do not overload the dryer, as overcrowding can reduce airflow and slow down the drying process.
Activate the Photovoltaic System
Connect the solar panel, which powers the dryer’s blower, to start inflating the tunnel and initiate the drying process. The solar panel charges a rechargeable battery, so the blower can maintain airflow throughout the drying cycle, even if sunlight levels fluctuate. This airflow accelerates moisture removal from the cassava and regulates the internal environment.
Monitor the Drying Process
The Solar Bubble Dryer requires minimal supervision, but occasional checks are recommended to ensure even drying. Use the built-in roller or internal rake to mix the cassava without opening the tunnel. This mixing helps to expose all parts of the cassava to the heated air, promoting uniform drying.
Check for Optimal Dryness
Drying typically takes 3-5 days, depending on weather conditions and cassava moisture content. Cassava is optimally dried when it reaches the desired moisture level for processing or storage, which can vary depending on the specific requirements.
Unload the Dryer
Once the cassava is fully dried, turn off the blower and open the tunnel carefully. Remove the dried cassava and prepare it for storage or transport. The dryer can then be deflated and easily moved to a new location if needed.
Store and Maintain
After each drying cycle, inspect the dryer for wear, clean the transparent tunnel surface to ensure maximum sunlight entry, and check the photovoltaic system’s functionality. Proper maintenance will extend the dryer’s lifespan and optimize its drying efficiency over time.