Second Nature

SUMMARY: This proposal is to develop and manufacture small, code-compliant, adaptable, moderate-cost, biogas digester systems that can be used anywhere in the world by people of all educational and cultural backgrounds.

PROBLEM SPACE: Biogas digesters were first developed in the 1950’s in India using “gobar” manure to produce methane gas and a nitrogen-rich fertilizer. In Asia, there are as many as 15 million, small digesters installed in primarily rural areas to provide cooking fuel, supply fertilizer/compost, improve sanitation, and safeguard water quality for individual families. These units are fairly primitive and have irregular gas output. In industrial societies, digesters are large and are used for waste treatment, farm and industrial residue, and recently, for reducing the volume of organic material in municipal waste streams.

SOLUTION: This proposal’s approach is unique because it combines elements of large, industrial digesters with those of small, primitive digesters to create a system adaptable to all cultures and circumstances. The main premise is that a safe, affordable, portable, small-scale solution that appeals to, and benefits, the widest possible audience will be able to improve living conditions for millions of people while reducing the negative impact of our species on the world’s ecosystems.

What is the solution?
The main component, an air-tight, recycled-plastic tank, contains naturally-occurring anaerobic bacteria that “digests” organic material in a water solution. The digester tank will be manufactured in different sizes to match the user’s input/output requirements. The contents are heated to 85 to 95 degrees fahrenheit, and are agitated with a mixing system to increase efficiency. The duration for organic material to remain in the digester tank varies from 20 to 30 days depending on gas output and degree of digestion desired. Digesters perform best when new material is continuously added at up to three day intervals.

Within the digester, bacteria reduce the volume of organic material by converting it to a gas, called biogas, which consists of 60% to 70% methane. Gas output is estimated at approximate 1.5 cubic meters of gas per day per cubic meter of digester volume. The gas is used directly for cooking/lighting/heating/refrigeration or is converted to electricity by a fuel cell or generator. Digesters also produce a primarily liquid, nutrient and nitrogen-rich, “slurry/compost” which has characteristics as good as, or better than, modern fertilizers.

The proposal is a modular system that will use the economies of industrial production and distribution networks to manufacture and install a network of small digesters worldwide. Collectively, these digesters will become a major producer of renewable energy. In developed countries the installations will have more features and be fairly automated, while in developing countries they will strive for simplicity and ease of use.

With options easily added to fit a wide variety of circumstances, the units will be easily transported, require minimal skilled labor to install and operate, and be usable in permanent as well as emergency/refugee installations.

The problems I am trying to solve and the preferred state I am trying to achieve.
The proposal offers a solution that is sensitive to native cultures in that it allows people to develop themselves within their own society without reliance on another political system or adaptation to an outside set of values. The goal is to provide a solution that educates each community that uses it, by engaging them in a hands-on way, toward a basic understanding of their participation in energy use and its vital relationship to living things.

This is in contrast to using fossil-based, non-renewable, sources of energy, and instead proposes that a portion of people’s energy be derived from renewable bio-mass. Coupled with this goal is the desire to reduce the need for centrally generated and distributed energy.

People in developing countries face many challenges in meeting basic needs. These problems are particularly acute in crowded, refugee settings where poor sanitation practices, such a open latrines, effect water quality due to sewage run-off, and encourages disease as a result. An anaerobic digester eliminates open latrines and manure run-off by converting the material to biogas and a liquid output (effluent) that is pathogen free.

Wood cooking-fires cause burns, and the smoke causes air-pollution and cancer, particularly in woman and children, who often spend hours searching for firewood every day. The effects of foraging for wood are significant in that the practice often denudes the landscape and results in desertification and erosion. Several of the mudslides in Haiti during hurricane Andrew were caused by deforestation as a result of intense wood gathering for cooking fuel.

In developing countries, a digester will encourage families to stay in one place because it will provide locally grown food, energy independence, and improves the surrounding ecosystem. As a result, there will be less migration and accompanying social conflict.

A digester, operating in a remote region, can provide gas for a clinic, school, orphanage or family. This can be used to run absorption refrigerators to keep medicine fresh, or be used for cooking or lighting. A digester can be used to heat water directly, or in sophisticated installations, power a generator or a small stationary fuel cell, whose waste heat, can warm the digester slurry for additional efficiencies.

A digester can provide stability and hope to a struggling family in a developing country, and a sense of pride to people in western cultures as they produce local food and energy while reducing their environmental impact.

What is the plan to implement it?
If awarded, the prize from this competition will be used to build and operate two or three prototypes, with the goal of developing an underwriter-certified, code-compliant, marketable, digester system. The intent is to then distribute and install one million, or more, units worldwide. It is anticipated that relief agencies, governments, institutions, companies and individuals, will install and operate the units to meet their needs.

Is it Comprehensive?
The proposal will reduce fossil fuel consumption, greenhouse gas production, soil erosion, deforestation, municipal solid waste volume, and migrations of people displaced by environmental degradation. The proposal will encourage local food production, stabilize developing societies, discourage centralized energy distribution, use “current” solar energy (plants and manure), improve sanitation, and reduce pathogens in water supplies.

Is it Anticipatory?
In the mid 1970’s, anaerobic digesters consisted of experimental “gobar” plants in India and municipal waste treatment installations in developed countries. Biogas digestion became widespread in China in the 1990’s and published data on small plants started to become available to western readers. Since then, large agricultural applications have become fairly common in the United States for manure run-off and odor control. In Europe, large industrial food residue and garbage digesters have become fairly common. There has been some use of biogas-sourced methane to power vehicles in Scandanavia.

It is anticipated that the interest in biomass sources of energy will continue. As people become more aware of the many benefits of anaerobic digestion, there will likely be continued growth in anaerobic digester installations worldwide.

Is it Ecologically Responsible?
The system’s operation has virtually no waste, and the components will be constructed of materials that are recycled, recyclable or reusable. The output is beneficial and the input is readily available. Other than in the manufacture/distribution of the components, solar and human power are the primary energy inputs.

Is it Verifiable?
The science of using anaerobic digestion to produce bio-gas and liquid fertilizer already has wide spread acceptance. The only aspect in need of verification is the business model and manufacturing/distribution protocol.
Is it Replicable?
Small scale digesters are replicable by almost anyone so inclined. They have been made using everything from abandoned oil drums to plastic bags.

Is it Achievable?
In developing countries a safe, portable and inexpensive digester will certainly be successful. In developed countries, people seeking a “greener” lifestyle, as well as those seeking the benefits of free energy and fertilizer, will embrace the technology if it is safe and convenient. Existing manufacturing, service and distribution networks can easily make the system available worldwide. As costs drop, use will become more widespread.

How will it be financed?
The cost of the first few units will be covered by funds received by this competition. The labor for the operation of the units will be free. Testing, engineering, manufacturing and legal costs will be financed by this competition. Once the testing and prototype development phase is complete, a start up loan/grant will fund the initial production, sales and distribution costs. After the manufacturing process is developed, the continued production and installation will be financed by sales to relief agencies, companies, institutions and individuals.

Who will implement it?
The development of the prototypes and business structure will be by the author, working with consultants and manufacturers. They will construct the prototypes, investigate regulatory issues and explore international sales and distribution networks.