How is biomass harnessed for energy

To narrow this alarming deficit, emerging several business and technological opportunities exist for renewable and alternative sources such as wind, hydro, solar and biomass. Biomass can exist in the form of agricultural waste residues or as dedicated energy crops grown on marginal and saline lands.

Pakistan has a large abundance of both, agricultural wastes such as rice husk, straw etc, and availability of marginal and saline lands which, if utilised to grow energy crops have huge potential as a renewable energy. Of all the above, biomass derived energy stands out because of three reasons. Second, biomass is the only renewable source with a defined effect of economics of scale which is important to lower production cost and maximise revenues in commercial settings.

Third, the use of biomass offer flexibility to place power generation plants near to biomass availability and electric grid. This not only offers a possibility for centralised bio-energy generation plants but also for starting a localised small power generation plants, especially in an area without electricity. A prime example is setting up a mobile biomass powered electricity production systems configured to power tube-wells and domestic usage.

The raw material biomass is available to farmers which can be stored until next crop is available. This strategy is better than solar powered pumps which are climate dependent, are temporal in use, involve security issues and are times more expensive than biomass powered technologies. Similar is the case with wind turbines with energy production dependant on wind speed varying through the year and a poor access to grid availability in remote regions.

Renewable synthetic natural gas Pakistan is a developing country with animal and human food production tightly associated with fertile land use. Therefore, conversion of non-edible biomass grown on marginal land is a successful strategy for cheap renewable, long-term, and large scale bio-energy applications. The prospect of growing energy crop is especially attractive since other agricultural biomass such as rice husk, bagasse and other residues are valued for their use as fodder, timber, paper industry or heating fuel in rural areas, and hence would compete with bio-energy industry.

We have experimented with energy crops such as switch grass, miscanthus and genetically modified sorghum for attaining maximum biomass on semi-arid land. Sorghum cultivation has shown yield potential of ton per hectare, has resistance to weeds and major pests and other common diseases all of which can improve economics in energy production.

By utilisng excess lands or degraded agricultural land for growing energy crop would earn extra income for farmers and landlords. Once a secure supply of biomass is achieved, it can be converted to synthetic renewable gas non-manure biogas which can be used in electricity generation, domestic use and the transportable sector. The country has developed technologies that can convert biomass into gas which is times faster and 20 times more yielding than any other manure derived from biogas.

Production of renewable synthetic natural gas from biomass holds maximum potential mainly because of three reasons. Biomass continues to be an important fuel in many countries, especially for cooking and heating in developing countries.

The use of biomass fuels for transportation and for electricity generation is increasing in many developed countries as a means of avoiding carbon dioxide emissions from fossil fuel use. Biomass contains stored chemical energy from the sun. Plants produce biomass through photosynthesis. Biomass can be burned directly for heat or converted to renewable liquid and gaseous fuels through various processes.

Direct combustion is the most common method for converting biomass to useful energy. All biomass can be burned directly for heating buildings and water, for industrial process heat, and for generating electricity in steam turbines.

Thermochemical conversion of biomass includes pyrolysis and gasification. Both are thermal decomposition processes in which biomass feedstock materials are heated in closed, pressurized vessels called gassifiers at high temperatures. They mainly differ in the process temperatures and amount of oxygen present during the conversion process.

Pyrolysis entails heating organic materials to — o F — o C in the near complete absence of free oxygen. Biomass pyrolysis produces fuels such as charcoal, bio-oil, renewable diesel , methane, and hydrogen. Hydrotreating is used to process bio-oil produced by fast pyrolysis with hydrogen under elevated temperatures and pressures in the presence of a catalyst to produce renewable diesel, renewable gasoline, and renewable jet fuel.

Syngas can be used as a fuel for diesel engines, for heating, and for generating electricity in gas turbines. It can also be treated to separate the hydrogen from the gas, and the hydrogen can be burned or used in fuel cells.

The syngas can be further processed to produce liquid fuels using the Fischer—Tropsch process. A chemical conversion process known as transesterification is used for converting vegetable oils, animal fats, and greases into fatty acid methyl esters FAME , which are used to produce biodiesel. Biological conversion includes fermentation to convert biomass into ethanol and anaerobic digestion to produce renewable natural gas.

Ethanol is used as a vehicle fuel. Renewable natural gas—also called biogas or biomethane —is produced in anaerobic digesters at sewage treatment plants and at dairy and livestock operations. It also forms in and may be captured from solid waste landfills. Properly treated renewable natural gas has the same uses as fossil fuel natural gas. Researchers are working on ways to improve these methods and to develop other ways to convert and use more biomass for energy.

In , biomass provided about 4, trillion British thermal units TBtu , or about 4. A collective term for all plant and animal material, biomass can take many forms — from plants and wood, to animal and agricultural waste. In power generation it is commonly used as wood pellets that are harvested from forests and burned to release energy. At a time when coal-fired power plants are being phased out due to climate and environmental concerns, it is becoming an increasingly-considered option for alternative power generation.

Biomass can also be used more indirectly, by converting organic material into biofuels that can be used as alternative energy carriers to traditional fuels like diesel or petroleum. So while the pros of biomass energy revolve around its potential as an alternative to fossil fuels, its major cons stem from concerns that it is still a fuel that releases emissions — and that large forested areas often need to be removed to produce feedstock.

As the availability of biomass sources such as plants, manure and waste may not diminish compared to finite fossil fuels, the alternative source of energy is considered by many as a renewable form of energy. Trees and crops can be replanted to offset those that are removed — although effective agricultural and land management is essential to ensure resources do not become depleted faster than they are used.

Other organic materials such as food and animal waste are constantly being produced, and on a much shorter timescale than it takes for trees to be cultivated. As biomass sources can be converted to fuels and electricity, they can help in reducing the dependence on fossil fuels. The global energy system is shifting its focus away from fossils like coal, oil and gas as measures are taken to address climate change, meaning new sources of energy are needed to fill the gap.

While renewable technologies like wind and solar will likely dominate the future energy mix, biomass-fired power generation has also emerged in this transitional period. Many former coal plants are in the process of converting their existing equipment to run on biomass feedstocks.

Meanwhile, biofuels will be important alternative energy carriers to fuels like diesel and petroleum, to be used in transport, heating and some industrial processes. There is some debate about whether or not biomass can in fact be considered a carbon-neutral source of energy. The argument in favour is due to the fact that, although carbon emissions are released when burning, plant material like trees actually remove CO2 from the atmosphere during their lifetime through photosynthesis.

If biomass power plants can be equipped with effective carbon capture and storage technologies, there is an extra dimension to claims of carbon neutrality — and some companies have even made bold claims for becoming carbon-negative using this technique. There is another aspect to consider too. Generating energy from organic waste materials can greatly help in waste management, which has become a major issue in many countries.