INNOVATIVE BIOMASS ENERGY SOLUTIONS FOR AFRICA

Pennisetum purpureum also known as Napier grass, elephant grass or Uganda grass, is a species of robust perennial tropical grass native to the African grasslands widely and naturalised in tropical and subtropical regions of the world. 

Napier grass is a monocot C4 perennial grass in the family Poaceae. It is tall and forms in robust bamboo-like clumps up to 4 metre high. It is a heterozygous plant, but seeds rarely fully form; more often it reproduces vegetatively through stolons which are horizontal shoots above the soil that extend from the parent plant to offspring. It is fairly tolerant of different soil conditions, has low nutrient requirements and remarkably drought tolerant for a plant of high rainfall areas

Napier grasses improve soil fertility, and protect arid land from soil erosion and is the most important fodder crop for the dairy farmers in East Africa. It is also utilised for windbreaks and biomass fuel production.

The grass is also used in push-pull pest management which involves the desired crop being planted alongside a 'push' plant, which repels pests, in combination with a 'pull' crop around the perimeter of the plot, which draw insects out of the plot. Napier grass has shown potential at attracting stemborer moths (a main cause of yield loss in Africa) away from maize and hence is the "pull" crop. This strategy is much more sustainable, serves more purposes and is more affordable for farmers than insecticide use.

As a carbon farming solutions plant it is an excellent biomass industrial crop. Plantations produce up to 40 tonnes of dry biomass per hectare per year with an average energy content 18 GJ per tonne, and the grass can be harvested many times per year.

Industrial and agricultural processes often generate large amount of low value biomass waste. Examples are sawdust, waste planking, 221§4321§coconut shells and husks, rice husks, maize cobs and peanut shells. Many of these products have a low protein value and of no nutritional value to people or animals.

Low density energy crops are also a good source of biomass for fuel. This biomass has a low value before densification and is often burned off to make way for new crops.

If raw biomass is left open to oxidise and rot, the biomass decomposes and causes methane pollution which is more harmful than CO2. It can however be transformed into usable energy in solid, liquid or gas form using conversion technologies.

An important energy conversion technology is to dry, reduce the by-product into a pellet form. The high pressure compaction process heats the material, which plasticises the lignin in the biomass and forms a natural bonding agent. The compressed pellets are easy to store, transport and have a high calorific value. The biomass pellets can be used for heating applications or for the generation of electricity.

PELLETIZING BIOMASS – ADVANTAGES & DISADVANTAGES

Dried compressed pellets have bulk density advantages over wet biomass, which allow them not only to successfully compete with raw biomass and, in many cases, with solid fossil fuel but also to displace them from the fuel balance. 

The main advantages of biomass pellets are as follows:

1. Significantly higher combustion heat than that from original biomass (by two or more times in most cases);
2. A high level of unification of the fuel composition, which completely excludes the necessity in preliminary treatment for the final consumer;
3. Inexpensive automatic fuel feed options to the boiler furnace;
4. Evenness and completeness of pellet combustio
5. The almost complete absence of smoke during their burning, which will significantly facilitate the utilization of ash and other wastes.

Some disadvantages of biomass pellets are also observed:

1. High hydrophilicity and the trend towards catching atmospheric moisture cause not only the excessive moistening of the pellets but also the complete destruction of their mechanical structure.
2. The susceptibility to biodegradation in the atmospheric air medium that is caused by the activity of different fungi and microorganisms excludes the long-term storage of pellets;
3. The necessity to maintain a high level of the dryness of pellets and of the surrounding air under other conditions being equal increases the fire and explosion hazard of bulk storage.

These disadvantages are solved if packed into sealed moisture proof bags at the time of manufacture.

In September of 2000, Tom Reed presented a paper at a biomass combustion conference in Austria detailing work done on a “turbo stove” which he called a fan driven “reverse downdraft” gasifier stove. The stove made use of the “wood gas” from the pyrolysis process and utilised the volatile energy in the biomass fuel. This development was ground-breaking as it was the first time that gasification, used extensively in industrial applications was applied to a cooking application.

The design was named a TLUD (Top Lit Up Draft) stove by Dr Paul Anderson, follower and colleague of Tom Reed. This stove design has been developed and improved over the last 20 years and is now regarded as an advanced biomass combustion device. It is now considered a modern biomass cooking device by ESMAP, the World Bank program looking at improving access to clean cooking in developing countries.

Gasification uses a fire chamber with a two stage closely coupled biomass combustion process that 1st heats the fuel, and converts the solid cellular components in the biomass into volatile combustible gases. The 2nd stage, above the 1st stage, burns the converted hot gas cleanly and efficiently.

This combustion technique dramatically reduces emissions and increases energy efficiency. It has been thoroughly tested as the deanest biomass combustion technique available

The downside of most TLUD stoves has been their cost relative to other simple stove designs and the ability for local manufacturing of the stoves. Since 2015 Ekasi Energy has worked modularising the TLUD design and making it suitable for mass production based on using steel sheeting and advanced fabrication tools for parts manufacture. the design was dubbed the "FabStove" (Forced Air Biomass Stove).

In 2021, we presented a “gasifier stove engine” concept, which separated the gasifier (the combustion part of the stove) from the stove frame. This development allows for most of the stove to be constructed from mild steel components and just the fire chamber and stove top to use temperature tolerant stainless steel.

In 2023, the stove wast tested to ISO standards and certified as meeting Tier 4 standards for efficiency and emissions. A partnership with Energy-G-Africa was entered into whereby volume production of stove parts will be manufactured by them and distributed as stove kits for assembly in local markets.

STEAMBIO AFRICA

SteamBio Africa sets out to address two significant challenges facing Southern Africa; the need for clean, secure and reliable energy, and the need to address the challenge of invasive woody biomass species. This includes encroacher bush in Namibia, Botswana and South Africa and alien invader tress in South Africa.

SteamBio Africa will use a novel superheated steam technology to thermally upgrade the biomass feedstock, yielding solid biofuel, water, and a mix of potentially high-value organic chemicals. Upstream benefits include the development of the harvesting value chains, contributing towards the restoration of degraded lands and drainage systems, as well as creating new local economic development opportunities.  

With support from the EU Horizon 2020 funding programme over 36 months, and a working pilot program in Namibia, we aim to address these challenges by adding value to problematic biomass resources in order to produce a clean burning, high value solid biofuel with coal-like properties. 

Downstream benefits include the supply and distribution of the biofuel, being a direct substitute for fossil coal in industrial applications, as well as a substitute for less desirable solid fuels in low-income households.

Ekasi Energy is the South African consortium member in this project and involved in the commercial development opportunities presented for biomass processing for industrial use.

For more information visit www.steambioafrica.com or see an overview at https://www.youtube.com/watch?v=78dU1MW8_rY

SMART HOME ENERGY DEVICE (SHE)

The SHE project will develop a commercially viable heating product with charging and lighting capability, that will go beyond heating but generate multiple possibilities. The project is funded by the Europe Africa Partnership on Renewable Energy (LEAP-RE) group to a value of 0,6 million euros (R12 million).

It is an international project with Tshwane University of Technology (South Africa), Makerere University (Uganda), Graz University of Technology (Austria) and the Institute of Mines Telecom (France), as well as the University Carlos III de Madrid (Spain) as an associated partner together with Ekasi Energy.

The SHE device will be based on an existing portable micro-gasifier cookstove, which is used with compressed wood pellets, the currently available best performing cookstove regarding CO emissions. This basic stove concept for wood pellets was developed by Ekasi Energy, together with TU Graz using a combined experimental approach and extensive CFD analyses. In this project the innovative SHE concept is developed addressing the main barriers that hinder the broad implementation of this technology, i.e. lack of electricity production and limits in fuel flexibility. This is achieved by combining for the first time: 

• Expanding fuel options to biomass pellets made from available agricultural residues and perennial energy crops as affordable and readily available fuels and burning these fuels in a manner that meets the WHO cooking standards respectively with extremely low emissions and high efficiency;
• Integrating a thermoelectric generator to generate electricity and connecting it to a solar panel and battery to power small appliances and lamps grid-independently; and
• Integration of a smart low-tech method to track carbon-dioxide emissions based on a database of relevant fuels to monitor the heat and electricity generated by the SHE unit and an algorithm that correlates this with fuel and carbon-dioxide savings.

Many research papers exist on micro-gasification with wood pellets. This project specifically focuses on a using a multi-fuel approach utilising feedstocks from sources other than wood, which is in short supply in Africa such as agricultural; residues and energy crops. The prototype designs will be extensively tested with communities in Uganda and South Africa.