How to turn trash into en­ergy in just 12 hours

Business Standard - - WORLD - JESS SHANKLEMAN

The UK might soon be pow­er­ing its lights with en­ergy that comes from the trash.

A Dan­ish en­ergy com­pany is work­ing on new ma­chines that sort house­hold trash from re­cy­cling, while rapidly break­ing down or­ganic ma­te­ri­als like food to cre­ate power from bio­gas pro­duced by the process.

Dong En­ergy A/S, which runs hun­dreds of wind tur­bines in the North Sea, says its plant 30 kilo­me­ters (19 miles) out­side of Manch­ester is one of the first to use en­zymes on an en­tire waste stream and then com­bine it with re­cy­cling sort­ing tech­nol­ogy. That would be par­tic­u­larly help­ful in cities where space is at a pre­mium and small apart­ments of­ten have room for only one trash bin.

The process “is a use­ful op­tion for lo­cal au­thor­i­ties and waste com­pa­nies that have not yet rolled out sep­a­rate food waste col­lec­tions,” said Char­lotte Mor­ton, chief ex­ec­u­tive of the Anaer­o­bic Di­ges­tion & Biore­sources As­so­ci­a­tion.

Dong, which is chang­ing its name to Oer­sted, says its “Re­ne­science” plant in North­wich will be fin­ished at the end of this year at a cost of 600 mil­lion krone ($95 mil­lion). It will help deal with Bri­tain’s moun­tains of waste, about a quar­ter of which goes to land­fill dumps, where it releases the po­tent green­house gas meth­ane as it rots.

“If ev­ery­thing goes well, this is go­ing to be a big show­case that peo­ple will come to from all over the world to see,” Thomas Dals­gaard, ex­ec­u­tive vice pres­i­dent of ther­mal power and bioen­ergy at Dong, said in an in­ter­view at the plant.

The Re­ne­science process starts with a giant claw that crunches into a moun­tain of trash and it ends with seven dif­fer­ent types of ma­te­rial—from plas­tics to met­als and bio­gas, that can be used to cre­ate elec­tric­ity, re­cy­cled or sold on to a scrap yard. Noth­ing goes to land­fill.

Re­ne­science en­zymes, like those found in wash­ing pow­der, clean trash for 12-hours in tanks 50 me­ters (164 feet) long, speed­ing up the de­com­po­si­tion process and tak­ing or­ganic ma­te­ri­als to an anaer­o­bic di­ges­tion plant where it’s used to cre­ate elec­tric­ity.

Any­thing that’s left is sorted through a se­ries of bal­lis­tic sep­a­ra­tors, con­veyor belts, mag­nets and shred­ders to give the fin­ished clean and re­us­able prod­ucts. While some left­overs from the process are cur­rently in­cin­er­ated, Dals­gaard said that will stop by 2020.

“You can be lazy and have a good con­science with Re­ne­science, and you can also solve an is­sue about space and we can solve what­ever resid­u­als would be from house­hold sourc­ing,” he said.

In fact, he reck­ons Re­ne­science is bet­ter than home sort­ing be­cause any waste food, like ketchup at the bot­tom of a plas­tic bot­tle is turned into elec­tric­ity rather than washed away.

If the tech­nol­ogy proves a suc­cess, Dong has plans to de­velop a se­ries of plants across the U.K., Europe and the world, in­clud­ing Malaysia. Bri­tain was the ideal place to start be­cause filling land­fills with moun­tains trash are get­ting more ex­pen­sive.

Cru­cially, the bio­gas that drives the en­gines can cre­ate a steady flow of power to back up in­ter­mit­tent elec­tric­ity gen­er­ated by wind and so­lar. That could pro­vide an al­ter­na­tive to plans for costly new nu­clear power sta­tions like the once be­ing built at Hink­ley Point.

“We would ar­gue that off­shore wind in a coun­try like this is very close to be­ing baseload, so com­bined with de­cen­tral­ized gen­er­a­tion in mul­ti­ple sites and stor­age, it could be a cost ef­fec­tive al­ter­na­tive to nu­clear,” he said.

Dong En­er­gyis work­ing on new ma­chines that sort house­hold trash from re­cy­cling, while rapidly break­ing down or­ganic ma­te­ri­als like food to cre­ate power from bio­gas pro­duced by the process

THE RE­NE­SCIENCE PROCESS

Step 1: A giant claw crunches into a moun­tain of trash

Step 2: The trash is cleaned with en­zymes for 12 hours

Step 3: The re­sult­ing or­ganic mat­ter “slurry” goes to an anaer­o­bic di­ges­tion plant, where it can be used to cre­ate elec­tric­ity

Step 4: The left­over ma­te­ri­als, now clean and re­us­able, are sorted into var­i­ous cat­e­gories such as fer­rous met­als and plas­tic

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