What a waste

The world today dumps over 70 percent of food waste into landfills, rather than harnessing it for fuel and electricity. An average city in the developing world generates around 4000 tonnes of waste daily! Over the next 25 years, global energy demand will grow by 50 percent, while global oil supply dwindles at a rapid pace. Waste-to-energy is an obvious solution to meet the world’s burgeoning energy demand, believe experts. The technology is well-known and the only problem is to organise collection, segragation and transportation.

A recent report “Waste-to-Energy Technology Markets”, which analyzes the global market opportunity for WTE, expects waste-to-energy to grow from its current market size of $6.2 billion to $29.2 billion by 2022.

Currently there are some 800 industrial-scale WTE plants in more than three dozen countries around the world, and likely thousands of smaller systems at individual sites. Most employ anaerobic digesters, which make use of microorganisms to break down and convert organic waste into a fuel such as biogas, biodiesel or ethanol. With some 70 percent of food waste around the world still going into landfills, there is a lot of potential feedstock to keep this environmentally friendly carbon neutral fuel source coming. The waste from small slaughterhouses, breweries, dairy farms and coffee shops can power hundreds of typical homes each day if the infrastructure is in place to sort, collect and process the flow of organic material.

If we cannot control the waste we generate, especially food waste, the next best option is to use it effectively instead of letting it go to rot or polluting land and air.

Waste not waste

Schwarzenegger may be gone but California continues to trudge heavily on the green energy path. Now it is the turn of human waste to generate energy!

California produced 661,000 dry metric tons of biosolids in 2009, according to the energy commission. Referred to as 'biosolids', these can also include a sludge of heavy metals and other toxins left over from wastewater treatment. While in some cases biosolids can be used as fertilizer for crops, they most often have to be disposed of in landfills.

"Existing options for using biosolids are limited (mainly land application and alternative daily cover in landfills) and face increasing environmental challenges that could eliminate those options," the energy commission noted. "Current disposal practices often involve hauling biosolids long distances, which consumes transportation fuels, increases greenhouse gas emissions, and increases ratepayers' costs for wastewater treatment."

A company now plans to use "steam/carbon dioxide reforming" technology to vaporize liquid residues and gasify the organic solid portion of biosolids in an airlock chamber. The company will pump in steam and carbon dioxide to create a hydrogen-rich gas that could be used in fuel cells to generate electricity.

This is a new experiment, worth watching! Plenty of source material everywhere.

What to do with waste

If there is one thing the world citizens have in abundance, it is waste. So, why not turn it into energy like so many are doing?

European countries have embraced Waste to Energy (WTE) as a way to reduce landfill growth as well as dependence on imported fuels. Today, about 400 WTE facilities are operating in Europe, using municipal solid waste as their primary fuel source. In Denmark alone, 29 WTE plants are currently in operation with 10 more on the way. In Sweden, the city of Kristianstad has essentially weaned itself off of fossil fuels in just ten years by replacing these energy sources with the city’s own waste.

If deployed across a nation like US, WTE facilities could reduce the volume of the more than 250 million tons (PDF) of material being thrown away each year by up to 90 percent. If burned properly, the remaining 10 percent would be mostly inert ash. With proper filtering systems in place, WTE facilities can meet and even exceed federal air emissions standards.

Yet, in the US WTE is being adopted in some regions while in many places it faces flak from environmentalists. Why? The problem is with the manual sorting and filtering required. The technology is safe – IF you can separate out hazardous materials (like batteries) in the incoming fuel (trash).

But like in any technology, there are trade-offs between cost and environmental costs. It would be foolish to look for something which does not have any negative fall-out. This is where we need to balance the positives against the negatives. With so much waste generated, time may not be far off when the waste starts spilling into our lives. More so when the use and throw culture seems to be spreading.

Hold on to sewage

What is scarce? - Energy, power. What is abundant? - Waste. And if you can convert the abundant into the scarce, what joy!

Engineers at Oregon State University have made a significant advance toward producing electricity from sewage, by the use of new coatings on the anodes of microbial electrochemical cells that increased the electricity production about 20 times.

The findings, just published online in Biosensors and Bioelectronics, a professional journal, bring the researchers one step closer to technology that could clean biowaste at the same time it produces useful levels of electricity -- a promising new innovation in wastewater treatment and renewable energy.

Engineers found that by coating graphite anodes with a nanoparticle layer of gold, the production of electricity increased 20 times. Coatings with palladium produced an increase, but not nearly as much. And the researchers believe nanoparticle coatings of iron -- which would be a lot cheaper than gold -- could produce electricity increases similar to that of gold, for at least some types of bacteria.

In this technology, bacteria from biowaste such as sewage are placed in an anode chamber, where they form a biofilm, consume nutrients and grow, in the process releasing electrons. Sewage is the fuel for electricity production.

The treatment of wastewater could be changed from an energy-consuming technology into one that produces usable energy. The technology already works on a laboratory basis, researchers say, but advances are necessary to lower its cost, improve efficiency and electrical output, and identify the lowest cost materials that can be used.

Now this is what makes more sense than trying to discover new sources of energy, right?

Renewable gas

National Grid, which distributes gas and electricity in northeastern US and the UK, says that renewable gas could meet 16% of demand.

Published in a white paper, Renewable Gas - Vision for a Sustainable Gas Network, the company research shows how biomethane produced from waste could meet the needs of its US customers in Massachusetts, New York, Rhode Island and New Hampshire. With investment of around $7 billion across the four states it covers, National Grid says renewable gas could meet up to 25% of demand and reduce greenhouse gas emissions by around 16 million tons a year.

Unconventional sources such as dairy farms, waste water treatment plants, landfills, wood waste and food waste plants will get linked into the grid. In fact, any unit that generates biodegradable waste can be a potential source. An excellent way to get rid fo colossal waste we generate too.

In the UK, National Grid has joined forces with British Gas and a local brewer, Adnams, to use waste from the brewing process to produce biomethane and inject it directly into the UK’s gas network. The remaining waste is an effective manure material.

Biopower - going waste

Garbage is a problem not only in developing world but also the developed world. Landfills are running out of space in UK which we read has decided to export waste pellets! In cities like Bangalore and Chennai and Kolkatta, you cannot drive too far without seeing some dump right within the city with waste rotting and flowing over.

What a waste we are letting all our garbage rot in landfills from where they emanate methane, etc. Instead we can be generating energy out of this waste both at individual flats level and community levels. There are people and organizations practicing this and happy with the same. Unfortunately, they are not news makers!

All it requires is 15 kgs of waste on alternate days for replacing the LPG for a family of 9. A moderate hotel can save upto Rs 75,000 annually by turning its waste into gas. The cost of disposal of waste for such a hotel is around Rs 25,000. Cowdung is also an excellent fodder for such biogas plants.

Success of such biogas plants however depend on proper segregation of the kitchen waste. Materials that can pose problems to the efficient running of plant are coconut shells and coir, egg shells, onion peels, bones and plastic pieces. While bones, shells and utensils can spoil the mixer physically, onion peels, coir and plastic can have detrimental effects on microbial consortium in the predigester and main digestion tanks. But above all, primary segregation of waste is the problem. If this can be inculcated at household levels, it could make a big difference.

Meanwhile, the total energy consumption generated from biomass in Sweden grew from 88terrawatt hours (TWh) to 115 TWh between 2000 and 2009, while the usage of oil-based products declined from 142 TWh to 112 TWh during the same period, according to the Swedish Bioenergy Association Svebio.

Biomass surpassed oil to become the number one source for energy generation in 2009, accounting for 32% of the total energy consumption in the country. It is projected that biomass consumption will continue to increase by another 10% in 2011.

A different kind of export!

Britain will start exporting domestic waste converted into fuel pellets to mainland Europe as it struggles to recycle the growing amount of household waste.

The generation of domestic waste seems to have exceeded the capacity of the British municipalities to recycle them. With limited land the solution of landfills is also completely exhausted. Hence the decision to export waste pellets to neighboring countries like Germany and Holland!

Household waste is turned into dense fuel pellets through a series of conversion processes like densification, removal of water and pressing. The resulting pellets can be directly used to generate heat which can then be used directly for heating purposes or convert water into steam to run a steam turbine for power generation.

In developing countries these energy conversion processes have been in use for quite sometime, for instance dried cow dung cakes are used as fuel. While it is illegal to export waste to other countries, through this project the energy value of the resource would be upgraded to a level from which significant benefits can be exploited.

The problem is that burning this fuel source releases carbon emissions. Conversion process of waste to fuel will have to be modified so that net energy content is increased while the potential of carbon emissions decreases.

Of course a simple way to make use of waste is to turn it into manure for unfertile soils!

Flying on waste energy

British Airways has announced plans to source a part of its fuel supplies from waste municipal waste to fuel plant. The company plans to procure 16 million gallons of green jet fuel annually from the Solena plant that would come up in London.

The plant which is expected to come online in 2014 would convert 50,000 tonnes of municipal waste into jet-grade fuel. The volume of fuel supplied initially would be 2percent of the total fuel consumption of British Airways. This would cut down on the carbon emissions that is generated due to the conventional jet fuel, kerosene.

British Airways aims to obtain 10 percent of its jet fuel waste-to-energy processes by 2050. London produces 3 million tonnes in organic waste every year.

Waste to energy process provides a three-pronged advantage. One, it helps in the management of the ever increasing waste in the cities, two, it converts the methane an efficient fuel and a greenhouse gas) which is produce from the decomposition of municipal waste and, third, its use results in reduction in carbon emissions.

Yet another waste to energy plan was announced by Delhi International Airport Limited (DIAL) last year. DIAL in partnership with two other companied will build a Rs 1.4 billion ($28.6 million) plant that generates energy using municipal waste.

The plant, to be built on 5.7 acres, is expected to be commissioned in late 2010
With about 4,000 MW of generating capacity, Delhi still has a shortfall of about 400 MW. In addition, Delhi's landfill sites are running out of capacity. The proposed plant would need 1,300 metric tons of municipal waste a day, which is 100 metric tons more than what Delhi produces each day. That could be the pitfalls of such plants, as waste quantities and moisture content are crucial for the operation of the plant.

The world needs more such ventures, not only to optimize on energy waiting to be tapped but also to tackle the alarming waste problem. If you have heard of individuals or groups undertaking such projects, write in to us. Let us share the success stories and scale them up.

Let us do our bit

Care to imagine the amount of waste we produce every month, and then every year? As consumption increases, so does waste. Imagine dumps and more dumps around the cities, growing every day.

According to the CES, IIsc round 3600 tonnes of solid waste is generated in Bangalore EVERY day. This is pretty much the same of most big cities.

Much of the biodegradable waste generated is high in organic content and with humidity content becomes difficult to incinerate. A better option would be biomethanation where bacteria degrade the waste to produce methane, or even simply composting the waste.

However, not much is done. Most of the waste is carried out of the cities to be dumped in the suburbs, or if they make it to the dumps, they are forgotten and end up polluting the soil and water. No real land-filling (covering the waste with soil) happens and the biodegradation takes a long time.

A far cry from recovering wealth from waste or reducing to zero waste! For example, 70 percent of San Francisco's waste stream is being diverted from landfills through a combination of strategies including waste avoidance, waste reduction, composting and recycling. The city's goal is to divert 75 percent by 2010, and to achieve zero waste by 2020.

The city's composting program (see picture) is the largest in the US, and began accepting food and yard waste in 1999. The majority of the compost created goes to area vineyards, and the rest to small farms and landscape suppliers.

What does it take to make our municipal authorities aware of the immense wealth in the waste?!

Recyclable materials are taken to the material recovery facility at Pier 96 where over 182,000 tons of material is processed each year. Of course, as we know and are t the receiving end, much of the recycled materials are shipped thousands of miles to the developing world where cheap labour sorts them out with bare hands!

While authorities wrangle over whose responsibility waste is, or which method or which contractor is best, there are simple things each one of us can do to help in the waste problem.

How about reducing the waste generated in our homes? All it requires is to make just adequate food. Next, segregate the waste and use the organic part in a small pit in the garden. This is something that can be done even inside. All you need is one small pot with a lid. Dump your wastes there and cover with a thin layer of soil. After few days the manure it yields could help the kitchen garden immensely.

Approximately we generate 2.5 kgs of waste per average household. Think of what a good idea it is to use this for a good purpose and save our countryside from swelling dumps.

Check out this interesting post at Treehugger.
http://www.treehugger.com/files/2009/03/what-really-happens-at-a-landfill.php

Waste again

The latest edition of Power Line has some interesting overviews of the national scene on biomass, cogeneration, captive plants, etc among which is one on big benefits from biomass and cogeneration. The case studies give details of projects. Among this is one on waste to energy (WTE) run by Shriram Energy Systems in Vijayawada and Guntur.

The plant processes municipal solid waste into refuse-derived fuel fluff. Put up at a cost of Rs 460 million, it generates 6 MW of power which it sells to AP Transco at Rs 3.70 per unit. Other renewable biomass fuels like rice husk are also used.

Around 505 tonnes of municipal solid waste (MSW) from the two cities is first treated for a reduction of moisture content from 45 to 25 percent. The dried combustible material has a calorific value of 1800-2400 K cal per kg.

The project was registered as a CDM one last year and enjoys a 10-year credit period.
Not only has the plant saved the cities the problem of finding landfills for its waste, it has turned the waste into wealth.

Experts often dismiss WTE in Indian scenario due to high moisture content and a low calorific value of waste generated. Costs as high as Rs 8 cr for 1 MW and a minimum requirement of 150 tonnes to generate 1 MW have been cited as unfavourable conditions. It is better to segregate waste and turn the organic part into composite, say some.

Some have even cast suspicions about the ‘actual’ fuel used to run the plants, claiming that many times these are the conventional fuels!

If you have authenticated information on successful WTE, do let us know.