Working with biofuels

Working with biofuels

Biofuels are more “sensitive” than conventional petroleum-based fuels. You can store petroleum for years, but biofuels degrade and need to be sold and used within six months of production. If not, the fuel oxidizes, creating corrosive by-products.This is bad news for car engines, especially for injection components vulnerable to acids. Ethanol poses its own problems: the fuel is very attracted to water, so it’s hard to handle
in humid climates like that of West Africa. In order to meet the specification required, the ethanol blending must be done by adding it into a gasoline blendstock (BOB). Micro-organisms can also grow around biofuels,
which means more frequent cleaning of storage tanks; and because biofuels act as solvents, they can dislodge sludge which then blocks pipes and delivery nozzles. Biofuels can also contaminate other fuels, and pose a particular threat to jet fuel used in airplanes. These problems are all soluble, however; and the ARA believe that with good quality management, testing, certification, and monitoring, biofuels could work well in many African countries. Existing service stations are mostly already adequate for storage and consumer sale, and transporting biofuels presents no real problems – apart from the ethanol-water issue. Because it is biologically- based, the hazard from accidental spills is less than from conventional fuels. There
is one known safety issue with FAME – the primary biofuel in biodiesel: fuel-saoked rags may spontaneously combust, and need to be disposed of with care.

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What’s the advantage of biofuels?

What’s the advantage of biofuels?

The promise of biofuels is that they let you have your cake and eat it: to drive cars ithout damaging the environment. The idea is that biofuels are a way to recycle carbon dioxide. CO2 is released when any fuel is
burned. But the carbon stored in petroleum or coal, has been there for thousands of years, so burning these fuels adds CO2 to the air. But biofuels are made from plants, which remove CO2 from the atmosphere as they grow: emissions are balanced by carbon capture. There are other potential bonuses, too. A large biofuels industry might help cut the price of oil, while start-up costs are low and could boost an agricultural economy, creating
jobs.

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Biofuels in Africa

Biofuels in Africa An African Refiners Association guide

Many of the biggest questions facing societies today come down to energy. Is oil running out? Are we destroying our climate with Greenhouse Gases? How can we make enough clean energy to light every home on the planet?
In all this discussion, much has been said about the benefits of biofuels. But is it all hype? Are biofuels an answer to the world’s energy problems? Or are they a distraction? We see biofuels in use in Europe, in Brazil, in the USA. But can they be introduced to Africa, perhaps saving billions of dollars in costs? Or are the technical problems too great?
This Guide, drawn up by the African Refiners Association –the cross-continent association that promotes pan-African cooperation in energy – offers some answers to these and other questions. What are biofuels anyway?
A biofuel is any fuel made from “renewable” resources. “Renewable” just means some-thing that grows – a tree, a plant or an animal. So humankind has been using biofuels for millions of years, in the form of wood,
charcoal, peat or animal dung. But recent advances in chemistry mean it is now possible to make liquid fuels from renewables – substitutes for gasoline or diesel. Up to a point...
Biofuels only work in most of today’s cars and trucks in blended form –mixed with regular fuels – either to make biodiesel (which is 7%biofuel), or to make a gasoline-ethanol mix(up to 25% biofuel), sometimes called “gasohol”. In Brazil, though, they have built cars which can burn 100% ethanol; and car-makers are starting to make “flex-fuel” vehicles, which can burn from 0% to 100% biofuel mixtures. Biofuels seem to be on the up.

There are three main sources today: trees, plants rich in vegetable oils, and sugar and corn which can be made into ethanol. Experiments are ongoing with new plants like jatropha; and with systems that grow hydro-
carbon-rich algae. In future we may make “second generation” liquid biofuels from plant cellulose – even from wood.

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Anaerobic Digestion and Biogas retain strong support despite the stuttering global economy

LONDON Globally, large investments and an increased emphasis on organic waste landfill diversion are driving anaerobic digestion (AD) through the economic gloom. On both sides of the Atlantic, the environmental profile, economic credentials and reliability of AD are making it an increasingly attractive proposition for waste management companies and investors alike.

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In the UK, the Prince of Wales’ private estate and Jacob Rothschild are among the high profile investors behind the $103 million investment in Tamar energy which plans to build 40 digesters in the UK alone. Meanwhile, in the USA, AgPower are set to open the largest AD facility on the continent this year. Waste management companies are among the significant players committed to AD and other new approaches in organics management; Tim Hawkins, Area Vice President for Waste Management Inc. commented; “As the nation’s largest environmental solutions provider, our customers are asking us to help them meet their sustainability goals.”
But despite enormous progress, the US and the UK lag significantly behind continental Europe in terms of development. The maze of bureaucracy in regulation and permitting, as well as the project economics are delaying the progress of AD as a feasible and widely implemented technology for utilizing organic wastes. Haley Sawyer of Navigant Consulting, in her article on the opportunities in Anaerobic Digestion said, “AD conversion requires a specific organic waste composition and a sufficient supply, without which biogas output will be lower, and the project will be uneconomic.”
The message from stakeholders across the industry is clear; Investment coupled with a serious commitment to sustainable goals and long term feedstock agreements will lead ultimately to an economic business proposition that provides genuine societal benefit. Renewable Waste Intelligence has provided a forum, in San Francisco, to address these issues of business model, investment, infrastructure and long term agreements.
The Anaerobic Digestion Conference and Expo is bringing together waste management companies, entrepreneurs, municipal authorities and investors to ensure that solid supply chains can be built for the long term: Take a look at: http://goo.gl/u7Gnm or email Oliver Saunders at osaunders@renewable-waste.com to find out more about how you can get involved.

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Types of Anaerobic Digesters

Types of Anaerobic Digesters Biogas Plant

Anaerobic digesters are capable of treating insoluble wastes and soluble waste-waters. Insoluble wastes such as particulate and colloidal organics are considered to be high-strength wastes and require lengthy digestion periods for hydrolysis and solubilization. Digester retention times of at least 10–20 days are typical for high-strength wastes. High-rate anaerobic digesters are used for the treatment of soluble wastewaters. Because these wastewaters do not require hydrolysis and solubilization of wastes, much faster rates of treatment are obtained. High-rate anaerobic digesters usually have retention times of less than 8 hours.
High-strength wastes are usually treated in suspended growth systems, whereas soluble wastewaters are usually treated in fixed-film systems. Several anaerobic digester processes and configurations are available for the treatment of insoluble wastes and soluble wastewaters . Each configuration impacts solids retention time (SRT) and hydraulic retention time (HRT). Minimal HRT is desired to reduce digester volume and capital costs. Maximal SRT is desired to achieve process stability and minimal sludge production Readmore

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