Over a billion individuals find themselves without electrical illumination once night falls, relying instead on hazardous fuels like kerosene, wood, or charcoal, if accessible. While advancements in solar and battery-powered lighting systems are emerging, particularly for clinics and organizations, billions remain in darkness. Many initiatives, ranging from grassroots makers to larger organizations, are striving to change this reality, and I am one of those involved.

The Weight of Responsibility on Women

The quest for fuel is a significant burden, consuming valuable time and energy. For those grappling with energy poverty, gathering or purchasing fuel is essential for cooking, heating, and lighting after sunset. This time could otherwise be spent on business endeavors by adults or on education for children. Unfortunately, girls often bear this responsibility globally, as families tend to prioritize resources toward fuel collection over education.

Burning carbon-based fuels, whether refined kerosene or charcoal, releases not only carbon dioxide but also harmful byproducts such as carbon monoxide and soot into homes. As primary cooks in many households, women face daily exposure to these dangerous chemicals. Organizations like PATH and the Global Alliance for Clean Cookstoves are working to provide efficient cookstoves to those in need, creating microindustries globally to tackle this issue. While this approach addresses cooking and health concerns, it does little to alleviate the need for light sources.

Fuel is not only costly but also limited. When fuel serves as a light source, access to illumination after dark becomes equally restricted. Having light in the evening can provide essential time for small business owners to continue their work or for children to study after completing chores, making a significant difference for families and communities.

Harnessing Solar Energy for Solutions

Women and girls not only bear the health risks associated with burning these fuels but also face heightened dangers of assault when accessing public latrines or water sources at night. Thus, integrating public lighting with solar energy systems can help address multiple challenges.

Numerous organizations are dedicated to distributing larger solar systems to communities worldwide. Solar Sister aids nano-entrepreneurs in establishing businesses that sell small solar lighting systems. Little Sun has been running a buy-one-give-one initiative for solar lights and mobile device chargers, showcasing impressive impact statistics on their website. Many small organizations are engaging in similar efforts, and I encourage you to support their missions.

However, there are limitations with these solar systems. Two key components—the lighting system and the battery—often cannot be produced by the users themselves. While some maintenance and battery replacement may be feasible, the production of these tools remains out of reach for the end-users. The pandemic has highlighted the fragility of our just-in-time supply chains, and while the components may be reusable, the battery often cannot be easily replaced.

The Quest for Sustainable Batteries

Typically, lithium-ion batteries are used, but what happens when they fail? If there is no replacement or recycling method available, the need for a battery "recipe" that individuals can learn and share becomes clear. This recipe must be straightforward, safe for homes with children, easily recyclable, and constructed with minimal skills or tools. I have developed such a solution (US10749168B1) and am currently creating a book to share this knowledge, along with collaborating with alpha testers to refine the technique.

My prototype, although rudimentary, has been operational for three years with minimal maintenance. It produces sufficient energy density to power a bright LED light throughout the night, using a battery size comparable to that of a car battery.

After nearly six years of experimentation, I have found that achieving 5 Wh/Liter is relatively easy, while 25 Wh/Liter requires careful planning. This battery chemistry is not ideal, but it meets essential goals and is rechargeable and serviceable. Although it cannot match the performance of lithium-ion cells, it can still power lights effectively.

Innovative Lighting Solutions

To maximize the efficiency of our LED lights, we can explore the possibility of pulsing the LED to create an apparent brightness while consuming less power. Early experiments utilized a "Joule Thief" circuit to boost low voltages to drive LEDs, yielding bright flashes that are imperceptible to the human eye.

This technique, however, can damage standard batteries if not managed carefully. Instead, a low-voltage cell, like the inkwell, allows for more robust lighting options. In my lab, I utilize a "Boost Converter" to run LEDs off the battery, requiring an increase in voltage for USB-powered devices.

Now that we have replaced the faulty battery with one that can be locally produced, we consider further improvements. Do we always need a bright white LED for illumination? For nighttime tasks, a less intense light could suffice, reducing the energy demands on the battery.

Exploring Color Efficiency

If our client requires light for walking to a public well, she needs visibility but not necessarily full color accuracy. By cutting down the energy consumption of an LED, we can enhance safety while utilizing less powerful batteries.

LED Driver Implementation

Utilizing a circuit to pulse the LED can create brief bursts of brightness that are energy-efficient. When these flashes occur rapidly enough, they provide a useful light without draining the power source excessively.

When applying steady DC power to an LED, it may draw around 120 milliWatts. However, with pulsing, we could achieve comparable brightness at only 160 microWatts—approximately 1000 times less power.

The Importance of LED Choice

Indium gallium nitride (InGaN) LEDs are exceptionally energy-efficient, but is white light always necessary? Alternatives like green or cyan light could be just as effective for situations where color detail is less critical.

Leveraging Biological Sensitivity

The human eye has two types of receptors: rods for brightness and cones for color. In low-light conditions, rods dominate, particularly sensitive to the blue-green spectrum around 505nm.

By focusing on this range, we can maximize the efficiency of light output while minimizing waste. A light source designed for longevity and efficiency in low-resource settings can make a significant difference.

Integrating the System

By selecting a 505nm cyan LED combined with an efficient pulsed driver, we can create a sustainable lighting solution.

Existing Solutions in the Maker Community

Innovators like Ted Yapo are already merging the efficiency of cyan LEDs with pulsed drivers to create long-lasting flashlights. Although they may be costly initially, mass production can make them affordable for communities in need.

As I explore options that do not rely on advanced microcontrollers, I aim to develop accessible solutions that can be crafted by local makers. This journey began with a serendipitous conversation with Mr. Yapo, who pointed out the need for practical solutions for developing regions.

Together, through collaboration and shared knowledge, we can illuminate the path out of darkness.

Stay Luminous, friends.

Learn More about Ted Yapo's Work

For more insights into Ted Yapo’s contributions, follow him on Twitter @tedyapo or visit his Hackaday pages detailing the decade flashlight.

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