Producing energy with biomass and sugar cane

Date de l'actualité
2021-12-21

Producing energy with sugar cane is possible! Indeed, some biomass power plants are powered by a second generation biofuel: bagasse. This is a residue from the production of sugar cane. This form of biomass is used instead of coal to power thermal power plants.

Focus on this renewable energy production method, its advantages and disadvantages.

The islands affected by this energy problem

Some islands do not have a connection to the mainland electrical grid. For these islands, the problems related to energy are very important.

Indeed, as it is impossible for them to be supplied with electricity coming from another territory, it is absolutely necessary that their network is autonomous in its operation. Thus, it is essential that the electricity is produced locally.

In general, the solution that has been found is to use fossil fuels and carbon. The implementation of renewable energies is therefore particularly important, especially through energy sources produced with local resources.

The use of sugar cane

During the production of sugarcane, the stalks are crushed to extract the juice. The bagasse is the remaining residue. It is washed to extract the maximum amount of liquid, then heated to reduce its moisture content. It will then be burned in a thermal power plant at more than 500 degrees.

This combustion will emit steam and turn turbines that will produce electricity. Most of this production will supply the local electrical grid, and the rest will be conserved to meet the needs of the production plant where the combustion is performed.

However, the exploitation of bagasse is not possible throughout the year, as the sugarcane harvesting period only takes place from July to December

Advantages and disadvantages

> Advantages

- Allows to valorize a resource which would have been simply a waste without this use

- Reduce the use of fossil fuels such as coal.

- Possibility of being stored. Bagasse is only used as fuel when energy is needed.

> Disadvantages

- The sugar industry is threatened

The competition is more and more important in this sector. This is worsened by the overproduction of some countries like Brazil and Thailand. All this has led to a significant drop in the price of sugar, which weakens the sugar industries. Thus, the number of small plantations has decreased in recent years.

- A contested environmental impact

During its combustion, bagasse emits CO2, like all biomass. However, the CO2 emissions linked to the combustion of bagasse are much lower than those linked to the combustion of coal.

It is difficult to find enough raw material to completely feed thermal power plants. In addition, it is often necessary to import wood pellets from foreign countries, with transport that increases the environmental impact of these operations.

The company Albioma is a major player in this energy transition, producing renewable energy.

"Faced with the climate emergency, Albioma is committed to drastically reducing CO2 emissions from its activities to reach 90% renewable in its energy mix by 2025 and nearly 100% by 2030.

To achieve this, the Group will notably convert its historical thermal power plants to biomass, in Guadeloupe and Reunion Island." Source: albioma.com

In 2019, renewable energies provide one-third of the electricity production on Reunion Island. Bagasse, meanwhile, accounts for 8% of this production.

How does a biomass plant work?

Biomass is a renewable energy source. It is the production of electricity and heat through the combustion of organic matter. The main interest of this energy production solution is that the raw material needed is inexhaustible if it is produced in an environmentally friendly way, unlike fossil fuels.

A biomass power plant produces electricity from the steam that is released during the combustion of raw materials. The combustion heats the water in a boiler, from which steam is released. This steam then sets in motion a turbine, connected to an alternator, which produces electric current.

Source : lendopolis

The dangers associated with this production

> Fire and explosion risks

Dusts like bagasse waste are likely to explode or burn.

For this to happen, the concentration of dust must reach a minimum explosive threshold in a small and confined volume and there must be contact with a source of energy (spark, static electricity, hot surface, etc.). The fuels used in sugar factories for heating or logistic operations (natural gas or fuel oil), the creation of explosive atmospheres by dust due to handling, grinding, sieving and transport, stocks in silos, are the source of fire and explosion risks.

The production and storage of alcohol also present a fire risk: ethanol releases combustible vapors on its surface that ignite and/or explode when in contact with a significant heat source (spark, flame, burning surface, etc.) above a certain concentration. It continuously emits vapors until saturation of the atmosphere in which it evaporates, and therefore a closed enclosure (tanks, reservoirs...) containing ethanol can be subjected to internal pressures increasing strongly with temperature.

> Chemical risks

Possibility of release of toxic gases (carbon dioxide CO2, sulfur dioxide SO2) leading to risks of intoxication.

Formaldehyde used to prevent or correct bacterial contamination in sweet juices, with periodic or punctual injection or as a surface disinfectant, is a skin irritant and a volatile organic compound which releases vapors at room temperature responsible for respiratory symptoms (asthma...).