Let’s Think Seriously About Alternative Energy Sources

Mohammad Mahfuzul Islam

April 17, 2026

FacebookTwitterRedditBlueskyEmail

Getty Images and Unsplash+.

The long and serpentine queue at the refuelling station is a simple reminder that the world cannot run without fuel. In the current situation, we have to consider various options to address the energy crisis in Bangladesh. Bangladesh, like many other countries, is suffering due to the oil crisis caused by the most recent geopolitical war. Wars are waged for the control of natural resources, driven by resource magnetism. The colonial era was heavily motivated by the plundering of natural and cultural resources.

Some farmers are concerned about the possibility of irrigation amid the oil crisis caused by the insane war. Some are already using solar energy to run deep tube wells to irrigate the agricultural land. Unfortunately, even in the age of aluminum, dependence on fossil fuels is still the dominant practice. In a country with abundant sun and wind power, the reliance on fossil fuels is incomprehensible. Power generators in urban areas to keep the flow of uninterrupted electricity to home and office infrastructures also rely on diesel. Even electric vehicles’ charging stations are run by fossil fuels.

In Borolekha, Bangladesh, an oil mine has been sitting idle for a long time without being utilized for extraction. We know the impact of oil drilling on the environment. If this oil mine were used, it would be a disaster for the adjacent environment. Oil mining always contaminates the water sources, making the local ecosystem suffer and crumble.

Brazil has reduced its dependence on fossil fuels and has been using ethanol to fuel vehicles. So, whenever there is a price hike or scarcity of oil, they are the least affected. Sugarcane-based ethanol is better than maize-based ethanol for the environment. In Brazil, many vehicles run on pure ethanol alongside mixed-type fuels. It is setting examples for other countries to follow.

In India, E-20 (20% ethanol and 80% petrol) is used in vehicles to decrease reliance on fossil fuels. Contrary to popular myth, it does not harm the engine and leaves a smaller carbon footprint compared to 100% fossil fuels. Although the mileage might be a little less, the environment would be saved more if vehicles were more dependent on ethanol.

Used Cooking Oil (UCO) can be an alternative to fossil fuels. Singapore is experimenting with the use of UCO and is keen on converting all vehicles to run on this renewable fuel. Instead of throwing away and using the same cooking oil again and again, posing a big threat to the consumers’ health, it has gone for an alternative use.

Spain is also experimenting with the possibility of using used frying oil to fuel airplanes. As a logical outcome, it could move to other vehicles to curb greenhouse gas emissions. Sustainable Aviation Fuel (SAF) is the goal of the industry to deal with the growing carbon footprint.

In Chile, recycled cooking oil is used by different vehicles to act responsibly to save the rivers, jungles, and streams from carbon build-up. They are happy that they are doing something to make a difference in the environment. Although they have to filter used cooking oil regularly to keep the engine moving, at the end of the day, they remain optimistic that positive changes can be brought about by responsible actions.

Bangladesh can think about the possibility of using UCO to deal with the fuel crisis and go for greener solutions. Instead of exporting UCO to other countries, it should tap its huge production of Used Cooking Oil.

Pakistan has become dependent on solar energy to meet the ever-increasing demand for electricity. Instead of looking at oil-rich countries for fuel, Pakistan is relying on solar power to solve its problem of electricity crisis. It can be a good example for other countries to follow the example and deal with their respective problems. Bangladesh is also in a good position to utilize solar energy to minimize the problem of frequent blackouts.

Nuclear power is not a good option for producing electricity. Even though it is very cheap, the cost of a nuclear disaster is huge. Japan, despite being the victim of a nuclear bomb, trusted the uranium-derived energy. But they learned the harshest lesson when there was a nuclear fallout caused by a tsunami in Fukushima.

Disasters in Chornobyl and Fukushima should help us wake up from the dream of becoming a nuclear power in producing electricity in Bangladesh. Rooppur nuclear power plant is a constant threat to the environment due to its probable fallout. It would be very difficult for the government of Bangladesh to deal with the cost of any future disaster. Our politicians can easily abscond if there is any disaster or a change in the political scenario, but the local people have to pay the price for generations.

Hydroelectric projects like the Kaptai Hydroelectric dam were a nightmare for the local people of Rangamati, who lost their ancestral land to the artificially created lake. Projects like this are disastrous for those whose homelands are taken away by a huge reservoir. Hydroelectric projects have become an ineffective method to produce electricity as they victimize locals by submerging their homelands.

Like other countries, kitchen garbage should be used to produce electricity. Right now, it is used only in landfills, which does nothing to meet the growing electricity demand. As a result, tons of kitchen garbage are wasted. In the coming years, Bangladesh can think about this possibility to address the energy issue.

We can say that Bangladesh should diversify its fuel sources to deal with the energy crisis. It is very sad that despite having various options, we are concerned about the reserves of fossil fuels. Dependence on other countries for fuel is a suicidal step. Although a globalized world indeed calls for international trade, sole dependence on imported products will be lethal for the country’s energy-economy complex.

The oil refinery that Bangladesh has is designed for refining crude petroleum, which is heavily dependent on oil imports; instead, it should focus more on refining kitchen oil for meeting future demand. Bangladesh should install its own refinery for processing frying oil like Spain and the UAE. In an increasingly precarious world, alternative energy sources should be the top priority of the new Bangladesh.

Mohammad Mahfuzul Islam is an anthropologist and a faculty member at Independent University Bangladesh (IUB).

What’s In Your Gasoline? Understanding U.S. Motor Gasoline Formulations – Analysis

April 16, 2026 

By EIA

Motor gasoline in the United States is a blend of hydrocarbons and chemicals, with specific formulas varying by region and season. To meet federal air quality standards, the U.S. Environmental Protection Agency (EPA) and state regulators require different formulations, depending on air quality and location, which affect performance, cost, and emissions. In addition, warmer summer months require a different gasoline formulation than cooler winter months. Key differences between formulations include octane rating, volatility—commonly measured as Reid vapor pressure (RVP)—and emissions. This year, the EPA will relax federal enforcement of summer RVP standards to help reduce gasoline prices.


What are the main types of gasoline formulations in the United States?

There are two main types of gasoline: Conventional gasoline is the standard gasoline blend used in areas of the United States that meet federal air-quality standards. Conventional blend gasoline meets basic federal limits on emissions and volatility. Most of the United States uses this formulation.
Reformulated gasoline (RFG) is required by the Clean Air Act in areas with high smog. RFG burns cleaner than conventional gasoline but is typically more expensive to produce. Approximately 25% of U.S. gasoline sales are RFG, according to the EPA.

Both types of gasoline are available in different octane ratings (regular, midgrade, premium) and are usually blended with ethanol. In addition to conventional and reformulated gasoline, refiners adjust gasoline blends for summer and winter.

Why do gasoline formulations change seasonally?

The EPA uses RVP to regulate gasoline volatility: the lower the RVP, the less volatile the gasoline and the less evaporative the emissions. To reduce smog-forming emissions, the EPA mandates that summer grade gasoline has a lower RVP (less volatility) to control evaporation, which would normally increase in warm weather. In cold weather, higher volatility helps engines start more easily.

How do RVP limits change across regions?

During the summer season, EPA limits gasoline in the continental United States to an RVP of no more than 9.0 pounds per square inch (psi). However, regulators apply stricter limits in areas with air quality issues, including:Gasoline with a RVP no higher than 7.8 psi in areas requiring federally mandated gasoline

RFG program gasoline with RVP no higher than 7.4 psi in federally designated areas
Gasoline made to specification for State Implementation Plans (SIP) that are more stringent than federal requirements

How does the RVP limit change through the year?

The summer season for retailers and wholesale purchasers runs from June 1 to September 15. For refiners and bulk terminals, it starts earlier, running from May 1 to September 15, to allow time for supplies of summer-grade gasoline to get from producers to retailers. Some areas require longer periods for summer-grade gasoline use to further control emissions. Although not mandated, switching back to winter-grade gasoline in the fall is common because of its lower production cost.

Why is gasoline with lower RVP more expensive?

Gasoline with lower RVP is more expensive to produce because it requires pricier components for blending. For example, butane, a low-cost octane booster, has high RVP that limits its use in summer or RFG blends. Instead, lower RVP gasoline uses more expensive components such as alkylate to maintain octane while reducing RVP, contributing to higher retail prices.

Do all states follow the same rules?

Not exactly. The EPA sets federal standards but allows states or regions to set stricter gasoline specifications. Arizona, for example, requires the use of Cleaner Burning Gasoline (CBG) in parts of the state. California has stricter requirements than the federal government.

Data source: California Air Resources Board

The California Air Resources Board (CARB) requires gasoline RVP has no more than 7.0 psi during the summer season. In addition, CARB requires longer periods for summer-grade gasoline. These requirements contribute to consistently higher gasoline prices in California.

Principal contributor: Alex de Keyserling

Source: This article was published by the EIA

The U.S. Energy Information Administration (EIA) collects, analyzes, and disseminates independent and impartial energy information to promote sound policymaking, efficient markets, and public understanding of energy and its interaction with the economy and the environment.

ALT FUELS

 

Vale signs charter deal with China’s Shandong Shipping to build ethanol-powered ships

Reuters | April 9, 2026 |

Valemax Sohar Max, one of the world’s largest ships in with a wind propulsion system. (Image courtesy of Vale.)

Brazilian miner Vale has signed a 25-year charter deal with China’s Shandong Shipping Corporation, which will build the world’s first two transoceanic ethanol-powered vessels under the agreement, a Vale executive told Reuters on Wednesday.

The two Guaibamax-class vessels, each with a capacity to transport up to 325,000 metric tons of iron ore, are scheduled to be delivered from 2029 onwards.

They will be equipped with rotor sails to harness wind energy and more efficient engines, among other energy-efficiency improvements, Rodrigo Bermelho, Vale’s navigation director, said.

“We see decarbonization as an irreversible trend,” he said. “It is at the core of Vale’s strategy, not only in maritime transport but across all the products we have been developing for the steel industry.”

Vale is one of the world’s largest iron ore producers.

The agreement comes amid the US-Israel war on Iran, as disruptions on international oil markets have reinforced the appeal of alternative fuels and greater diversification in maritime transport.

“Situations like the one we are witnessing show the importance of having a flexible system that can adapt to different market conditions to ensure business continuity,” Bermelho said.

He noted Vale’s shipping operations have not suffered any material impact from the war.

Bermelho declined to disclose the value of the charter contract for confidentiality reasons, but said the deal includes an option for additional vessels.

Vale operates a fleet of around 50 Guaibamax vessels and has already announced the chartering of another 10 dual-fuel ships, capable of running on methanol and heavy fuel oil, from Shandong, with deliveries scheduled between 2027 and 2029.

The miner is studying the possibility of converting these vessels to also use ethanol.

(By Marta Nogueira and Fernando Cardoso; Editing by Chizu Nomiyama and Rod Nickel)

Mining Giant Vale Orders World's First Ethanol-Powered Giant Bulkers

Vale plans to build at least two Guaibamax bulkers running on ethanol (Vale)

Published Apr 9, 2026 7:29 PM by The Maritime Executive

Vale reports it has entered into an agreement with China’s Shandong Shipping Corporation to build the first large ocean-going vessels that will use ethanol as their primary fuel. It is an adaptation of its current design for the massive Guaibamax vessels (325,000 dwt) and follows news from earlier this year that reported Vale and Everllence were working on ethanol as a marine fuel for its engines.

According to Vale, the agreement with Shandong includes 25-year contracts for the construction of two vessels, with an option for additional ships. The adoption of these second-generation Guaibamax vessels, which are 340 meters (1,115 feet) long and have a capacity of 325,000 tonnes, is part of the Brazilian mining company’s multi-fuel strategy. In addition to ethanol, these vessels will be capable of using methanol and heavy fuel oil, and their design also allows for conversion to use liquefied natural gas (LNG) or ammonia. 

Shipping companies and the engine manufacturers have reported they are exploring ethanol as an alternative fuel. While there are concerns over supply, it is easier to handle than ammonia, which is toxic and highly corrosive. Maersk reported last December that it was exploring ethanol aboard its pioneering methanol-fueled feeder ship Laura Maersk. Everllence reported in September 2025 that it had success testing ethanol on its large two-stroke engines in the factory. 

“The use of ethanol as fuel in the ships that transport our ore, combined with the adoption of rotor sails to harness wind energy, places Vale in a unique position for the energy transition in global shipping over the coming decades, whilst driving similar initiatives in the sector,” said Rodrigo Bermelho, Vale’s Director of Shipping.

Considering the full fuel cycle from well to wake, Vale highlights that ethanol can reduce carbon emissions by around 90 percent (in the case of second-generation ethanol) compared with heavy fuel oil. In addition to maritime transport, Vale’s adoption of ethanol in its logistics operations includes trials on trucks at its operations and on locomotives on the Vitória a Minas Railway (EFVM). 

The new ethanol-powered ships will be similar to 10 other dual-fuel vessels (methanol and heavy fuel oil) that Shandong will deliver to Vale starting in 2027. The second generation of the Guaibamax will be equipped with five rotor sails to provide wind-assisted propulsion, as well as more efficient engines, hydrodynamic devices, a shaft generator, frequency inverters, and silicone paint, among the energy efficiency improvements. Vale says this set of technologies applied will reduce GHG emissions by around 15 percent compared to the current generation of Guaibamax. These technologies and alternative fuels are being tested as part of Vale’s Ecoshipping program. 

The mining giant had reported in October 2024 that it was proceeding with the installation of rotors on one of its 400,000 dwt vessels. It was part of an agreement with the Japanese owners of the NSU Tubarao and Anemoi Marine. The company also added Norsepower rotors to one of its Capesize bulkers.

Vale’s chartered fleet includes first-generation Valemax vessels since 2011, second-generation Valemax vessels since 2018, and, since 2019, the first generation of Guaibamax. According to the company, these vessels are among the most efficient in the world and can reduce CO2 equivalent emissions by up to 41 percent compared to a standard capesize vessel.   

 

Exmar’s Pioneering Ammonia Dual-Fuel Gas Carriers Named at Hyundai Shipyard

Pioneering ammonia dual-fuel gas carriers were named ahead of their delivery starting next month (Exmar)

Published Apr 9, 2026 6:47 PM by The Maritime Executive

 

Two innovative vessels, which are being billed as the world’s first mid-size gas carriers with ammonia dual-fuel engines, were named as they are nearing completion. The vessels, which were ordered in 2023 and 2024 by Exmar, a specialist in gas shipping, are being built at the Ulsan, South Korea, shipyard of HD Hyundai Heavy Industries and are viewed as the cutting edge for a new era in shipping.

The ships, which are each 46,000 cubic meter gas carriers, were named Antwerpen and Arlon in honor of two Belgian cities. Each measures 190 meters (623 feet) in length and is specifically designed for the transport of liquefied gas cargoes, including ammonia and LPG. Exmar highlights that the vessels were deliberately lengthened 10 meters (approximately 33 feet) in the design stage, along with a slight increase in beam to achieve a meaningfully higher cargo intake compared to the standard design. Hyundai developed the proprietary technology and the three tanks, which provide 45,000 cbm storage below deck, and two 500 cbm deck tanks.

HD Hyundai highlights that ammonia (NH3) can be stored in pressurized tanks at around 8 bar or in refrigerated tanks at -33°C without the need for cryogenic technology. In liquid form, it has about 1.7 times higher storage density than liquefied hydrogen (-253°C) at the same volume, making it suitable for large-scale, long-distance transport and storage of hydrogen.

One of the key features of the design is the ability to use cargo as fuel. Exmar says this creates significant operational flexibility and environmental advantages. It reports that the ammonia dual-fuel technology enables CO2 emission reductions of up to 90 percent during navigation.

 

The mid-sized gas carriers are the first to be outfitted with the ammonia dual-fuel engines (Exmar)

 

The ships also feature shaft generators and a selective catalytic reduction (SCR) system to reduce nitrogen oxide emissions.

The safety concerns about ammonia were addressed by equipping the vessels with advanced detection and mitigation systems. They have an ammonia gas detector for real-time leak monitoring and an ammonia purge recovery unit. These ships are the first of four being built for Exmar. They are currently completing outfitting and are scheduled for delivery in May and late June.

For HD Hyundai, the vessels represent a significant achievement in its strategy to pursue high-value vessels and new technologies. It highlights the ammonia gas carriers as the next step following its 2016 delivery of the world’s first methanol-powered petrochemical product carrier and the 2023 delivery of the first methanol-powered containership. Designs for the ammonia gas carriers were developed through a partnership involving HD Hyundai, HHI-EMD, Wartsila Gas Solutions, WinGD, Lloyd's Register, and Exmar

While the expectations remain high for ammonia as an alternative maritime fuel, DNV highlights that there are only three ships in the world currently operating with ammonia, two tugs and one offshore supply vessel. However, it calculates that there are currently 46 vessels on order, with as many as 18 scheduled for delivery in 2026 and reaching 46 vessels by 2030.

HD Hyundai highlights the forecast by the International Energy Agency that projects ammonia will account for eight percent of marine fuel demand by 2030. It is projected to rise to 46 percent by 2050. Ammonia is also seen as a likely carrier, as it can be used to transport hydrogen when combined with a cracking process at the destination.

EcoNavis to Validate and Demonstrate Improved Design for Wind Rotors

EcoNavis adds an appendage to the rotor to increase its performance and address changes in wind direction (EcoNavis Solutions)

Published Apr 7, 2026 5:57 PM by The Maritime Executive

 

Scotland-based EcoNavis Solutions believes it has a technological innovation that can enhance the performance of wind rotors. With wind-assisted propulsion gaining increased interest, the company is using a Scottish Enterprise research grant to move its concept from the drawing board to validation and demonstration.

The basic concept of the wind rotor promoted by Anton Flettner in the 1920s remains largely unchanged after more than a century. The spinning rotor captures the energy of the wind to provide additional thrust for ships and has become one of several competing technologies in the sector.

EcoNavis, however, points out that there are limitations to the original technology that impact its reliability. Issues such as a change in wind direction can reduce the effectiveness and also mean that ships require more route planning to maximize the effectiveness of the technology. 

The company has patented a tail-appendage device, which it says can increase thrust, reduce power demand, and widen the range of wind angles in which the rotor sail can operate efficiently. The tail enables the company to essentially broaden the rotor’s effective “wind window” and reshape the wind flow in the rotor’s wake.

It delivers higher thrust with lower torque demand. EcoNavis reports initial simulations indicate an increase in thrust of up to 10 percent with a 5 percent reduction in torque.

“Flettner rotors already offer one of the highest lift-to-drag ratios among wind-assisted devices, with a relatively modest footprint, but the main drawback has been the narrow band of wind angles – typically beam and stern-quarter winds,” said EcoNavis CEO and founder Dr. Batuhan Aktas. “By recovering energy that would otherwise be lost and optimizing the flow behind the rotor, we can provide a Flettner rotor design with a greater operational range.”

The fixed aerodynamic appendage downstream helps to stabilize the airflow behind the rotor. The company says it will permit the rotor to continue to generate thrust as wind conditions change.

By recovering energy that would otherwise be lost and optimizing the flow behind the rotor, EcoNavis believes its EcoRotor Sail can offer greater operational range. It says shipowners can have greater flexibility in route planning and more consistent performance over a typical trading year without fundamental changes to vessel operations.

The next phase will move into physical testing. Development of the EcoRotor Sail is being backed by a £100,000 ($133,000) research grant from Scottish Enterprise to take the £265,000 ($352,000) project through to validation and demonstration stages.

Enzyme produced by fungus may replace chemicals in the paper industry

Fungal xylanase can be obtained by cultivating the microorganism in sugarcane bagasse or wheat bran. The solution is a non-polluting alternative for bleaching cellulose pulp, which currently uses a toxic chemical

Fundação de Amparo à Pesquisa do Estado de São Paulo

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

This graphic diagram presents the main aspects of the study 

view more 

Credit: Diandra de Andrades/FFCLRP-USP

A trio of researchers from the University of São Paulo (USP) and São Paulo State University (UNESP) in Brazil have developed a method to obtain an enzyme from a fungus cultivated in agricultural waste that promotes cellulose pulp bleaching, an important paper production process.

Supported by FAPESP, the study was published in the journal Bio Resources.

Cellulose pulp is typically bleached using chlorine-based oxidizing agents, such as chlorine dioxide. These chemicals are highly toxic and can contaminate wastewater and the atmosphere, releasing gases that are harmful to human health. 

In addition to being produced from agricultural waste, the enzyme has the advantage of exhibiting greater thermal stability than many fungal enzymes described in the scientific literature, expanding its potential applications in industry.

“This is a more sustainable alternative for the paper industry that reduces the use of toxic chemicals and whose results show good potential for application. Since Brazil is a global leader in eucalyptus pulp production, developing cleaner bleaching technologies is especially strategic for the country,” says Diandra de Andrades, the first author of the study. She conducted the research as part of her postdoctoral work at the Ribeirão Preto Faculty of Philosophy, Sciences, and Letters (FFCLRP) at USP with a fellowship from FAPESP.

The work is part of the activities of the National Institute of Bioethanol Science and Technology (INCT Bioetanol) and is related to two projects supported by FAPESP (23/01547-5 and 18/07522-6). They are both coordinated by Maria de Lourdes Teixeira de Moraes Polizeli, a professor at the FFCLRP-USP and also an author of the article.  

The obtained enzyme was xylanase, which degrades xylan. Xylan is a hemicellulose found in the cell walls of plants, such as eucalyptus. It can be used in paper and pulp production. Xylanase facilitates the removal of xylan fractions associated with residual lignin in the pulp after industrial wood cooking. This contributes to increased brightness and greater efficiency in subsequent stages of pulp bleaching.

The xylanase was extracted from Aspergillus caespitosus, a soil fungus first described in the United States in 1944 and first isolated at USP in 2001 from samples collected on the Ribeirão Preto campus. 

The researchers cultured the fungus on two agricultural residues – sugarcane bagasse and wheat bran – using the solid-state fermentation method. Both substrates were advantageous due to their low cost, ease of fungal growth, and high xylanase production. 

Using sugarcane bagasse and wheat bran aligns the process with the concept of a circular bioeconomy by adding value to abundant Brazilian agroindustrial waste.

“The sugarcane bagasse became more efficient when we pretreated it with sodium hydroxide [caustic soda], which separates the cellulose from the hemicellulose and lignin, facilitating penetration of the fungus into the fibers. Wheat bran, on the other hand, didn’t require pretreatment because it has good availability of carbon, which is the main energy source for the fungus,” explains Polizeli.

However, the researcher emphasizes that local availability is an important factor to consider when choosing a substrate because it can lead to increased costs. In regions with high sugar and ethanol production, such as the interior of the state of São Paulo, sugarcane bagasse would be the most suitable substrate, even considering the need for pretreatment. In wheat-producing regions, such as Rio Grande do Sul state, wheat bran would be the most suitable.

Process

Pulp bleaching cannot be fully carried out using fungal enzymes because the process requires high temperatures that the enzymes cannot withstand. However, over the years, Polizeli’s group has demonstrated that the Aspergillus caespitosus enzyme tolerates temperatures around 60 °C, whereas many fungi cannot withstand much more than 40 °C. 

“As the bleaching process progresses in the factory, temperatures gradually decrease. As a result, our enzyme can be used in the final stages of the process, when temperatures are close to 60 °C, acting as a complementary step to conventional chemical bleaching and reducing the need for chlorine dioxide and, consequently, the chemical load of the process,” Polizeli explains.

Currently, the group is exploring ways to immobilize the enzyme on a chemical support so that it can be reused more frequently and withstand higher temperatures. 

One promising approach involves using magnetic nanoparticles combined with nanocellulose, which could even be used for enzymes in other industries, such as for producing bioethanol. The results highlight the potential of Brazilian biodiversity as a source of sustainable biotechnologies with industrial applications.

About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

---

Journal

BioResources

DOI

10.15376/biores.21.1.1690-1705 

Article Title

Agro-residue Valorization for Thermostable Xylanase Production by Aspergillus caespitosus and its Eco-friendly Application in Pulp Biobleaching