New Ways to Look at Old Waste

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The race is on to find more cost-effective, energy-efficient strategies for turning biomass, or renewable feedstocks, into alternative fuels. But just as important, researchers are seeking ways to produce these fuels without compromising global food supply and land.

In recent years, more attention has been given to creating energy generated from waste and from biomass consisting of organic materials. This renewable energy is favorable because the process produces fewer toxins, is easier on the environment and sends less waste to the landfills.

Photo: Nationalgeographic.com

Scientists at the University of Nottingham are developing ways to use the banana waste to produce fuel. Photo: Nationalgeographic.com

Ethanol made from corn grain, beets, sugarcane, wheat and other first-generation feedstocks is getting a bad rap these days. That’s because of its association with land and water resource concerns, waste toxicity and food crop competition. So, more attention and resources are going into the producing of ethanol and other biofuel types from second-generation feedstocks, sometimes known as non-food crops.

The processing of non-food feedstocks into biofuels is gaining momentum because it produces minimal greenhouse gas emissions, it’s less costly to process, it has minimal land, water and food crop demands, and it has the potential to create much needed new markets in the biofuel industry.

Another plus is that ethanol produced from second-generation feedstock has high performance and compatibility with traditional combustion engines and current energy infrastructure, including refineries and pipelines.

The New Ethanol

Some new techniques for producing biofuels include the production of cellulosic ethanol made from inedible and wasted parts of feedstocks, such as plant stems, leaves and stalks, wood residues such as straw, sawdust and papermill scraps and other agricultural waste. These types of waste are known as lignocellulosic biomass. But lignocellulosic biomass is difficult to process because their difficult-to-separate fibrous make up. So, researches are hard-at-work to uncover different methods to separate these tough structures in order extract the sugars needed for the process of ethanol production.

One new approach that’s gaining attention is the thermophilic method. This method involves the manufacturing of genetically engineered microbes, particularly enzymes, to degrade lignocellulosic structures and ultimately transform biomass into methyl halides – the material used to produce gasoline and other liquid fuels usually derived from petroleum.

A team at Oak Ridge National Laboratory is using such an approach. The team is studying a bacterium, or bioprocessing microbe,that can break down cellulosic biomass into sugars for fermenting into ethanol.

The Pyrolysis Method

The pyrolysis method, or biomass-to-liquid method, takes this concept a bit further. This method produces pyrolysis oil, or bio oil. The process of pyrolysis involves recovering materials from waste without the need for separation of its components. Instead, the fibrous materials are heated through pyrolysis (heating in the absence of oxygen) and results in the production of a liquid oil that is then refined into syngas.

New Uses for Waste

About one billion tons of inedible parts of agricultural food crops end up as waste worldwide, and up to 50 percent of food produced in the U.S. goes to waste. So while researchers are working on ways to refine second-generation biofuels, there are some unusual waste feedstocks making their way into the alternative fuels industry.

Olives

During the manufacturing of olive products such as olive oil and table olives, the olive stone, or pit, is discarded as waste by the olive industry. But researchers in Spain have discovered a way to break down the stone’s cellulosic fibers into sugars that can be fermented to make ethanol. The process puts to use the up to 4 million tones of olive stones wasted every year.

Olive stones are cleaning up the environment in yet another way. Scientists have discovered that the pits from olives and dates actually absorb pesticides. ScienceDaily reports that, “Directly applying natural organic absorbents to cultivated soil not only helps to stop the pesticides leaching away and thus reduce their use, but also helps to improve soil fertility.”

Styrofoam

Styrofoam waste, or polystyrene waste, has potential for becoming a new source of fuel. Engineers at Iowa State University are using the waste plastic to improve the power output of biodiesel. The polystyrene is dissolved in biodiesel to increase its viscosity and build pressure inside fuel injectors, increasing the overall output.

Electronic waste

Discarded computer hardware, including circuit boards, keyboards and casings, are being used to make raw materials for use in consumer products like fuel and plastics. The technique used involves utilizing a thermophilic method and chemical filtration process to remove hazardous toxins so that the waste materials can be safely recycled into other products.

Bananas

A team at Australia’s University of Queensland is working on turning banana waste into biofuel. The method involves extracting methane from bananas that are rejected at packing sheds.

The bio-methane produced will then be used to provide fuel to vehicles that run on natural gas.

Researchers at The University of Nottingham are finding even more ways to turn banana waste into fuel. Using simple handheld tools like meat mincers, the non-food parts of the banana, like the leaves, stems and peel of the banana, are ground into a pulp, mixed with sawdust and molded into briquette shapes. Once the briquettes are baked they’re ready for use as a fuel.

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