Cows are controversial. You can get jail time if you kill one in India or you can get a full belly (and perhaps some indigestion) if you eat one in the West. Cow farts and burps are responsible for so much greenhouse gas emissions that the UN has even considered a fart tax, yet their excrement has the potential to power entire cities!

Anaerobic digestion

It is through the process of anaerobic digestion (AD) that cow dung alchemically transforms to energy gold. AD is similar to composting. Biodegradable waste such as food, grass, and cow manure are typically used to feed the digester, except the digestion process happens with no or little oxygen.

In this biological process bacteria breaks down the waste as it naturally would, except instead of outputting methane into the air as happens at a landfill site, the biogas is burnt to produce electricity, heat or fuel.

Useful applications

AD produces a number of outputs, not just energy. Once dried, the digestate can be used as bedding in animal stalls, as a replacement for chemical fertilizer, or even as structural building materials like particleboard.

The EPA certainly has caught wind of cow dung’s many virtues. They’ve created AgSTAR, an outreach and educational program to promote recovery and use of methane from animal manure.

Pennwood Farms is one example of just what AgSTAR is trying to promote. With partial government funding the Pennsylvania-based farm built an AD system that produces 920,000 KWH annually from their 570 cows’ manure, enough to power their own farm with some to spare, which they then sell back to the grid. The electricity they produce is estimated to be the equivalent household consumption of 600 people.

And the environment benefits not just from reduced energy consumption. Manure managed through AD is far better than conventional livestock operations, which fill up huge lagoons with manure that sometimes gets pumped out onto open land, contaminating the water supply.

Yet even if every livestock operation had the costly anaerobic digestion technology, the problem livestock pose to the environment is far from solved. Cows, pigs and other livestock eat a lot. They spend much of their day eating and digesting… and farting and burping. Though their solid output may be harnessed and put to good use, their gaseous output is a different story.

Livestock and methane emissions

The FAO estimates that 18 percent of the world’s greenhouse gas emissions come from the livestock sector, in large part due to the methane emissions of livestock. Methane is 20 times better at trapping heat in the atmosphere than CO2, according to the EPA.

And the problem is only increasing as the growth of the global livestock sector remains faster than any other sub-sector of the agriculture industry. “The environmental costs per unit of livestock production must be cut by one half, just to avoid the level of damage worsening beyond its present level,” notes the FAO in its report Livestock’s Long Shadow-Environmental Issues and Options.

So while electric vehicles gain popularity as a means to reduce carbon emissions for the transportation sector and solar panels for home, comparatively little is talked about this giant GHG emitter that’s only increasing as the world population continues to swell.

Some hope?

For New Zealand, methane emissions are no joke. With approximately 35 million sheep and 8 million cows, about half of the country’s greenhouse gas emissions come from their livestock sector. So they’ve created a program to reduce agricultural emissions.

In one study, scientists are placing animals in boxes made of clear acrylic resin to measure their emissions. Their goal is to develop a vaccine that will stop animals’ methane production and increase their digestive efficiency, which also means feeding them less and saving farmers some cash.

With 55 million cows, Argentina is another country concerned about its livestock emissions. It’s estimated that 30 percent of the country’s total GHGs come from cows.

Researchers there have strapped balloon-like backpacks to the cows and attached tubes to their stomachs to study their digestive systems. The hope is to improve cows’ digestion. Silvia Valtorta of the National Council of Scientific and Technical Investigations found that methane emissions can be reduced 25 percent just by feeding cows alfalfa and clover instead of grain.

So instead of going through the trouble of putting cows in fart chambers and strapping backpacks to them, a much simpler alternative is to just change their feed. Cows aren’t meant to eat grain, so it’s no wonder they’re bursting with methane. Kind of like feeding a human grass all day, perhaps?

Creating a new technology to deal with a problem to then consume more and more, doesn’t solve the problem, it just makes it hurt a little less. It’s a little like popping an antacid to calm a stomach when the real issue is stress. Even if these new technologies were cheap enough for every farmer to use, what are the side effects? The technology side focuses on do, do, without enough think, think.

Part of the answer here lies in nature. One that grass-fed beef producers have already figured out. Put a cow on pasture and let it eat what it’s supposed to eat and it’ll emit less methane. The other part is simply reducing consumption (or avoiding meat altogether). A high-meat eating nation like the U.S. consumes 2½ times more meat than is recommended. So for all the talk about cow waste, the biggest issue here is actually the waste of cows.


image maraker (Creative Commons BY-SA)