Biomass

Biological pyramid of biomass

Like the food pyramid, the pyramid of biomass will include producers and consumers. Instead of showing the movement of energy through the trophic levels of a food chain/web, the pyramid of biomass shows the energy movement within a given area and given time.

Biomass pyramids indicate the relations between different trophic levels and their quantification. The energy is calculated from the dry mass of living organisms.

Fig. 1 - Biomass pyramid in an ecosystem

Calorimetry

The chemical energy stored within the biomass (dry mass) can be estimated using a calorimeter.

The calorimeter is used to measure the heat involved in this process. More specifically, a bomb calorimeter will be used to measure the heat released from a specific biomass sample. Bomb calorimetry is carried out in the following steps:

1. A sample (liquid or solid) that can be combusted is weighed.
2. The sample is blazed into a "bomb" vessel.
3. The vessel is filled with oxygen which ignites the sample, and it will start to burn.
4. The temperature increase in the vessel is measured as a calorific value (CV). This value can be calculated by comparing the number with previous sample combustions of a known substance.

Types of biomass used in the renewable fuel industry

You will often come across a slightly different definition of biomass within the renewable fuel sector. Biomass can also be referred to as a renewable and sustainable fuel source derived from organic matter (wood, crop, animal waste etc.). This is because the organic components can be recycled. For example, plans will release their nutrients into the soil as they decompose. You can have a detailed look at this process in our article Nutrient Cycles.

We use many types of biomass fuel in our daily lives. Wood is the biggest resource.

Fig. 2 - Biomass sources in an ecosystem

Forestry residue

Trees removed for commercial use usually leave unwanted parts in the logging sites. Pre-commercial thinning is often performed. The biomass used for fuel will include dead trees, commercially "unfit" trees (from thinning) and other unwanted parts such as diseased branches.

A lot of this waste will also be used by the industry making the waste.

Dedicated energy crops

Crops may be grown not only for food but also to provide biomass for fuel. There are two types of dedicated energy crops - herbaceous and woody.

Herbaceous crops, such as wheatgrass, are perennial, which means the plants will usually live for more than three years. Wheatgrass has high biomass and is classified as a C4 plant.

Woody plants include fast-growing hardwood trees (dicot trees). For example, maple, cottonwood and walnut trees.

Agricultural crop residue and animal waste

Agricultural crop residue often includes wheat, rice straw and corn stover. The residue is usually used to produce animal feed. Crop residue can also minimize soil erosion by wind and water. It can also provide thermal protection to the plants during cold temperatures.

Animal waste is often used as a natural fertiliser in agriculture. Livestock manure can also be used to produce fuel. The fuel can generate electricity for industrial and domestic heating and transportation.

Municipal waste and sewage

Municipal solid waste and commercial waste can be used to make refuse-derived fuel. Food waste collected with your recycling will also be biofuel. Alternatively, you could make your own compost from your food waste if you have a garden.

First, sewage will be treated to produce sewage sludge. After the treatment, it can be used as a fertiliser by the farmers. The leftover water containing invisible dirt particles will undergo other treatments to remove harmful bacteria.

Advantages and disadvantages of using biomass within the renewable fuel industry

We will cover some advantages and disadvantages of using biomass as a fuel resource.

Table 1. Advantages and disadvantages of biomass as a renewable fuel source.

Although biomass has a lot of advantages and the potential to be a good renewable source, it is still in its early developmental stages compared to other renewable sources, such as wind and solar power.

Biomass used as fuel is largely held back by its lower efficiency, space and costs. Biofuels are often blended with conventional fuels to counteract this efficiency problem and improve fuel economy. However, the efficiency still needs to be tackled before biomass can be a completely viable alternative to fossil fuel.

Biological farming

Biological farming can be defined as a chemical-free method of farming practices. Biological farming focuses on improving the microbiology of the soil to increase plant growth and produce yield.

Practices to increase the efficiency in energy transfer

To increase efficiency, farmers could:

• Reduce respiratory losses of farmed animals, such as reducing their movement. More energy will be transferred to the human food chain.
• Simplify human food chains. This will also lead to higher efficiency as less energy is lost to weeds and pests. You can do this through the use of herbicides and insecticides.

Advantages of biological farming in agriculture

We will discuss the main advantages of biological farming practices.

Sustainability

Biological farming aims to establish long-term soil fertility without artificial fertilisers, which require non-renewable resources for production. Organic fertilisers are used instead, such as manure and compost.

Biological farming allows the soil to sequester carbon. Various management practices such as integrating nitrogen-fixing legumes and crop rotations can increase carbon return into the soil. This helps to mitigate the greenhouse effect.

Biodiversity

• At the gene level - organic farms use traditional and adapted seeds. These are better adapted to battle diseases and more resilient to other external factors (e.g. climatic stress).
• At the species level - organic farms can act as refugee locations for wild plants, preventingbiodiversity loss in the area.
• At the ecosystem level - as an overall view, the ecosystem in an organic farm will generally produce a lower yield of crops. However, it will have greater biodiversity of species.

Oil

By growing a diverse combination of plants and animals, soil content is improved, and the nutrients and energy are recycled. More structured soil will reduce erosion and provide shelter for soil-living organisms. You will attract re-colonizing species, including birds, pollinators, and pest predators, by not using pesticides.

Disadvantages of organic farming

There are disadvantages to organic farming as well. Some examples include:

• Organic farming will often produce a lower yield.

• The quality of the crop will fluctuate during different years and seasons.
• Higher costs of the product.
• More intensive work is required, and more monitoring is required.