Wednesday, August 27, 2014

Coffee in the Morning, Biogas in the Evening

coffee The Huffington Post has a story about the waste generated by items you use in the morning, though it stretches things a bit by including your cell phone and clothing. The interesting one is coffee:

[O]ne of the major sources of river pollution in Central America is coffee processing plants since large volumes of wastewater are generated from the separation of the coffee bean from the cherry.
The story recommends you buy “shade-grown” or naturally grown coffee, though I imagine it is processing coffee that creates the problem not growing it. Still, I wondered whether coffee processors, whether on their own or by government regulation, might have a means to do something about the wastewater.
Why, yes, at least some do:
The Energy from Coffee Wastewater project by UTZ Certified has proven that is possible to generate energy, tackle climate change and protect water resources by treating discharges from coffee mills.
How does it generate energy? Through the production of biogas that is used to power small communities. Frankly, this sounds like methane, which isn’t very climate friendly. The Biofuels Association of Australia offers this definition:
The term 'biogas' is commonly used to refer to a gas which has been produced by the biological breakdown of organic matter in the absence of oxygen. The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen and the resultant energy release allows biogas to be used as a fuel.
That doesn’t inspire confidence, nor does this:
Myth: Biofuels don’t have any environmental benefits.
Fact: Biofuels produce significantly less CO2 emissions over the full life cycle of production through to use.
Less than what? Wood? Oil?

To be honest, it would take more research to balance the risk with the benefits – perhaps even to identify the risks and benefits. In this cursory look, making energy from coffee wastewater would seem to solve two problems – clean up the water and electrify villages – but at the cost of producing methane – not to mention carbon monoxide (deadly) and hydrogen (explosive).

Ecovillage lists the pros and cons of biogas and finds it, in sum, worthwhile. The disadvantages it identifies are these:
  1. The process is not very attractive economically (as compared to other biofuels) on a large industrial scale.
  2. It is very difficult to enhance the efficiency of biogas systems.
  3. Biogas contains some gases as impurities, which are corrosive to the metal parts of internal combustion engines.
  4. Not feasible to locate at all the locations.
Naturally, we’d recommend throwing up a couple of nuclear facilities – and joking aside, nuclear can scale and it can provide economic uplift, both as an employer and through generating electricity. Some Latin American countries (Bolivia quite recently) are considering it and some (Argentina, Brazil, Mexico) have built nuclear plants. But it isn’t the complete solution – it can’t answer directly to the coffee wastewater issue, for example – and biogas seems to have the capacity to provide small scale electrification and clean up the water.

Not every energy source can solve every problem – and some, like biogas, might work especially well in specific niches. We shouldn’t ignore that, especially in developing countries. Electrification is key to that development – and the moral imperative of improving people’s lives can burn away many first world objections. Nuclear energy and biogas both can be said to have their places in achieving that goal, even if biogas might seem problematic at first blush.

A visit to UTZ Certified is worth the trip to get a fuller view. Apart from the wastewater project, this coffee industry group aims to improve farming methods with an eye on sustainability. Sounds good – hopefully, it can do some good.

Edit: I refer a couple of times to making energy from wastewater. It’s really from the coffee processing waste that would otherwise go into the water. Still, using the waste this way keeps the water clear, so the point is still valid.

4 comments:

Anonymous said...

If think you may have missed the central idea of biogas. You grow something (coffee, cows, whatever). You harvest the cash crop (coffee beans, milk, whatever). You have stuff left over that will rot and produce methane. Here is your choice: put the stuff in a land fill where the methane will be released to the atmosphere or digest the stuff, capture the methane, and use the methane. So, you do not compare biogas to wood or nuclear, Instead you compare to rot in land fill or get some use from it. Make sense?

Mark Flanagan said...

Anon - you're right that burning methane is better than letting it drift away from waste. But its lack of scalability, somewhat unstable nature and the inefficient production process - which in part contributes to its lack of scalability - make it more appropriate for the kinds of niches that have been found for it. But if it solves the coffee wastewater problem and provides additional benefits, I'm all for it.

Engineer-Poet said...

There's more than one way to scour organics (wastes which increase BOD) from water.  Both wetlands flora and some biota such as mycelia have proven effective at capturing such organic molecules and leaving water clean.  But both of those are aerobic rather than anaerobic, and generally produce things other than a fuel stream.

Marcel F. Williams said...

Nuclear energy could actually help to greatly improve the efficiency of utilizing bio-waste for fuel.

If nuclear electricity were used to power plasma gasification facilities for converting biowaste into biofuels, methanol could be produced for: peak-load electricity production in modified gas turbines or for conversion into to carbon neutral gasoline for automobiles.

However, the pyrolysis of biomass for fuel waste about 80% of its carbon content. So if nuclear power were also used to produce hydrogen through the electrolysis of water, the amount of biofuel produced could potentially be increased by 400%.

Marcel