Turning Yucky Stuff into Energy – It’s a Gas

Two things we try to avoid stepping in are garbage and manure. Yet, disgusting as they may be, these two members of the biomass clan are sources of renewable energy. Just not in their usual forms.

Take garbage. Day after day it is trucked out to huge landfills where it gets buried by more garbage. As the trash piles up, the lower layers become starved of oxygen and the conditions near the bottom of the heap become anaerobic, allowing anaerobic bacteria and other microorganisms to feast on the garbage, creating landfill gas, a mixture of methane and carbon dioxide.

Once a landfill is full, it is usually capped by thick layers of dirt and often a sealing membrane, and left to sit, while more landfill gas accumulates. Finally, collection wells are drilled and cased to the base of the landfill. The section of the casing penetrating the waste layers is perforated so the landfill gas can enter the pipe. Unlike natural gas wells, landfill gas must be pumped out of its reservoir.

Agricultural wastes such as manure, crop residue, and silage are collected in a digester, a large, domed tank, often built underground. Again, as the waste accumulates, the lower section becomes oxygen-starved and anaerobic microbes acting on the waste produce methane and carbon dioxide. Because the material in the digester is a thick liquid slurry, the biogas rises to the top of the digester where it can be siphoned off. Once the slurry has been digested, the residue can be used as fertilizer.

With both processes, the carbon dioxide must be removed before the biogas can be used as fuel. Biogas can be used as a substitute for natural gas in fuelling electricity generation, space heating, and natural gas powered cars and buses.

2009: A Year in Waste

When it comes to energy there’s just something fascinating about waste products. Sure, the material’s almost always gross, but the idea of using garbage that would otherwise lay in piles or puddles makes great economic and environmental sense. Vancouver, for example, has plans to build six new waste-to-energy plants, dealing with the problems of residential garbage burning and reduced landfill capacity in one fell swoop.

So, in the spirit of sifting through piles for the best and brightest ideas, here’s a review of some of the icky, useful subjects that Flow waded through in 2009.

Banana peels

As it turns out, banana peels aren’t just for slapstick anymore. Like other cellulosic materials, bananas’ fibrous peels aren’t worth eating, which makes them a perfect source of biomass. The skins and leaves are mashed into a pulp and mixed with saw dust, which eventually hardens into bricks that can be burned as fuel.

Mountain pine beetle-killed wood

With mountain pine beetles spreading as fast as warmer winters will let them, the amount of wood destroyed by their infestation is growing. But while wood that’s been chomped on by the beetle’s larvae is useless as building material, it can still be packed into dense pellets for use as fuel. In fact, British Columbia has already integrated these wood pellets into its energy strategy through the BC Bioenergy Strategy.

Lumber mills

There are several ways to use the waste from lumber mills to create biofuels, from extract sugars from waste wood that can eventually be refined into ethanol, to the less tested bio-butanol, which has a more difficult refining process. Either way, in a country where “timber” is practically as important a phrase as “hello,” there’s no sense in letting wood waste go, well, to waste.

Manure

Manure, droppings or plain ol’ poop: call it what you will, but in the right hands the brown stuff is practically golden. Stories about the use of animal droppings as a fuel source were always cropping up in 2009, from a German town using its cows’ manure to produce biogas to chicken droppings as a source of heat to burning the methane from pig manure to produce electricity, no source is to smelly to be useful.

Shrimp shells

It takes a catalytic agent to turn biomass like canola oil into viable biofuel. As it turns out, an ideal source for that catalyst might be the chitinous shells of shrimp, which can not only increase the efficiency of biofuel production but, unlike other catalysts, is reusable. Hand it to researchers in Wuhan, China for turning a cocktail appetizer into a cleaner source of energy.

Finnish fish

All right, they don’t technically have to Finnish fish, but scientists in Finland are looking at the possibilities of fish waste in biodiesel. Between using fish’s chopped-off bits as an energy source or oceanic pollution, which would you choose?

Coffee grounds

Have you ever spilled a hot drink and watched a dark stain ruin the page you’d been reading? As it turns out, coffee’s (or tea’s) staining power can actually work to your advantage in a refillable ink cartridge fed by old grounds.

German town becomes world’s first

“What Can Brown Do For You?”

This memorable UPS slogan is being taken to heart by the German town of Lünen’s 90,000 residents, who will become the first in the world to use cow and horse manure for cheap green energy. Starting in December 2009, poo will be powering more than a third of the town’s heat and electricity.

How does it work? I’m so glad you asked. Animal waste and crops such as corn, wheat and grass from local farms are ahem, dumped into heated tanks, where natural fermentation breaks it down into methane and carbon dioxide.

This biogas is then burned to generate electricity and heat in a combined heat and power plant (CHP). The heat is then distributed across the town through a new biogas pipeline, which is being built underground using a horizontal drilling robot. A horizontal drilling robot? Yes really! We mention this only because a) it sounds really cool and b) roads are not disturbed, making for a viable model for other cities. 

The new sustainable solution isn’t causing a stink amongst residents, either; on the contrary, residents heating their homes with biogas won’t even notice a difference…or a smell. All they’ll notice is a savings of 30% or more on their energy bill. This is prompting other cities worldwide to stand up and take notice.

Lünen could become a model for the future of cheap sustainable electricity.

That’s really natural gas.

Potato biofuel

Ah, the noble potato. Famous for feeding the Irish, as the perfect complement to hamburgers, and a word Vice President Dan Quayle couldn’t spell. 

Now, it may assume another aspect of fame – as fuel. You’ve heard of PEI’s Cavendish Farms – it’s one of the continent’s largest French fry producers. Recently, Cavendish officially opened a new biogas plant at its main potato processing plant. There’s nothing revolutionary here. The process is relatively simple. The plant will take waste from the production of fries – water and solid – and compost it. That’s it. The composting process creates energy, which will be used at the plant. 

That may not sound like a big deal, but it adds up in a hurry – and we’re talking about quite a lot of potatoes. When fully operational, the biofuel plant will reduce overall greenhouse gas emissions by up to 35 per cent. 

Potatoes are potentially a lucrative source of biofuel. Corn has been the biofuel crop of choice, for two reasons. First, it’s energy-rich; and second, corn is abundant. However, as biofuel gained in popularity, it created a problem: a lack of corn to actually eat. 

Two years ago, a study at North Carolina State University found an alternative: potatoes. Specifically, the researchers thought sweet potatoes most promising, but “regular” potatoes – like the ones they turn into French fries – are no less viable.

The natural place to start, of course, is a potato processing plant.

Groundhogs predict, but can they change… climate?

One day after North American groundhogs predicted six more weeks of winter (or not), we are reminded by media reports that, really, it’s all “a pack of lies”.

In less civilized circles, one might suggest the famous woodchucks are full of *ahem* manure.

But in the race to produce new, viable alternative energies, being full of it might just be the solution. Could groundhog dung be the biofuel future?

According to the Toronto Zoo: yes, poo is the answer. 

To be more exact, the Toronto Zoo has a plan to build a plant that will convert animal and food waste into biogas using bacteria. The biogas, in turn, will fuel electricity production—electricity that will be sold back to the grid and pay for the $13 million facility over five years.

So how much dung can 5,000 animals produce? Enough to make this green endeavour worth the investment. Zoo curator David Ireland says “this stuff is gold.”

But, back to groundhogs and woodchucks, it seems there is an untapped feces opportunity. They’ve been predicting climate for years; maybe it’s time the fluffy forecasters break into biofuels and help in the fight against climate change.