Bioenergy
Outlook
Amid all the publicity surrounding wind and solar energy , it is easy to forget that bioenergy ( the generation of energy from biomass ) accounts for about 55 % of all renewable energy , or roughly one-tenth of the world ’ s primary energy supply . The IEA foresees a rapid increase in the use of bioenergy to displace fossil fuels , and demand is rising by about 6 % or 7 % a year ( 1 ) . This upward trend is supported by generous subsidies in the USA and many European countries .
Biomass
Biomass is organic matter used as feedstock in bioenergy facilities . The earliest form of industrial bioenergy was mostly ethanol , a corrosive alcohol used , among other things , as motor fuel . It is made from corn , yeast , sweet sorghum or sugar cane using a fermentation process . With the passing of time , more feedstocks and more products were developed . Forest and agricultural residues , crops , straw , waste , sewage , landfill gas and algae ( see box ) were used to create new products such as liquid biofuels ( especially biodiesel ) and biomethane ( biogas ). Biofuels are especially important in aviation , and biomass-fired
Are algae a viable fuel source ?
In the past decade , algae have been viewed as a promising biomass from which to produce energy . However , investment has greatly diminished because of the perceived drawbacks and costs . Although algae grow fast and can easily be turned into oil , they require vast quantities of water , and there are high costs and difficulties of oil extraction . Among companies that have closed their algae operations are Algenol , while Shell and Chevron discontinued their R & D programmes . However , Totalenergies and Veolia are building a demo biofuel facility near Marseille , France , which will harness algae to produce oil by 2025 . Reliance Industries is working to convert sunshine , CO2 and seawater into bio-oil . Other organisations are taking up the challenge , using new technology to improve productivity . The USA ’ s National Renewable Energy Laboratory uses medium temperature and low pH to more extract lipids from the algae to further process them into biodiesel . Indian Institute of Technology , Delhi has designed different models of biofilm reactors to cultivate microalgae .
power plants fuelled by organic matter such as waste , often in combination with natural gas or coal , have become increasingly popular . Many fossil-fuel power stations have been converted to biomass . Most biomass power plants feature cogeneration ( combined heat and power , or CHP ) for district heating , making them more efficient . A case in point is the Fortum Värtaverket KVV8 CHP plant in Stockholm , which has been operating since 2016 using advanced technology supplied by Andritz ( boilers , automation etc .) and actuators from Auma . It runs on forest residues but can switch to coal , and supplies heat to 190,000 households .
Liquid biofuels
Liquid biofuels include ethanol and biodiesel . Ethanol is used as an engine fuel and as a fuel additive such as E10 . The largest producers by far are the United States and Brazil . Biodiesel is produced from organic matter through a chemical process known as transesterification . It replaces diesel in ships , trains and automobiles . Aviation biofuel ( bio-
Raizen , Brazil : harvesting and processing plants to produce biofuels . Photo © Paulo Fridman ( https :// creativehub . shell . com ).
18 Valve World August 2023 www . valve-world . net