By Suzanne Vanderhoef
Imagine if pigs or some wild grass could help you heat your house or fuel your car. St. Louis-based Roeslein Alternative Energy produces renewable natural gas (RNG) from the anaerobic digestion of swine manure, turning pig poop into power. The company is also in the process of creating renewable natural gas from the digestion of native prairie plants.
Working in partnership with Smithfield Foods – the world’s largest pork producer – Roeslein takes the manure made by pigs and deposits it into giant lagoons, which are about the size of a small pond. The lagoons are then covered with impermeable covers that keep rainwater out and trap the manure inside.
Using anaerobic organisms, they break down the manure. The process produces CO2and CO4, better known as methane. While methane is a highly destructive greenhouse gas if it gets into the atmosphere, they are able to capture it, inject it into natural gas lines and transport it across the country.
“(This year) we’ll produce about 140,000 dekatherms or a million BTUs,” said Chris Roach, President of Roeslein Alternative Energy. That’s equal to about two million gallons of gas per year.
“In the total amount of fuel used in the country, it’s not huge,” explained Roach. “But it starts to become big numbers for a project like ours in terms of what is the scale, what is the efficiency and what is the economic return for that piece of what we’re doing that allows us to keep expanding.”
One way the company is planning to facilitate that expansion is by planting prairie grass – which can be converted to biofuel — on marginal land. Marginal land has little agricultural value and is generally not profitable to farm. However, that type of land can be used to create renewable natural gas from native grass.
“Twenty to thrity percent of the root structure dies off each year, which is essentially sequestering carbon,” explained Brandon Butler, director of communications for Roeslein. “It replenishes that every year by pulling carbon out of the atmosphere, so you get this constant deposit of carbon soil which becomes that good soil that forms the breadbasket of the U.S., which was all prairie before we turned it all into corn and bean farmland.”
Butler described how the grasses from this prairie restoration can be harvested and put into an anaerobic digestive machine that breaks down the plants and turns them into a renewable natural gas.
There are additional benefits to planting the prairie grass, including the creation of wildlife habitats; and its roots grow 10 to 15 feet deep helping to prevent erosion and runoff, which otherwise occurs due to the undesirable characteristics of marginal land.
Roeslein is planning to implement this type of prairie grass program along waterways in order to put back in place a natural sponge that will sequester carbon in the soil. The company said the program will not only generate new soil through the decomposition of the root system, but it will also alleviate flooding.
Currently, Roeslein’s manure-to-natural-gas facilities are on nine farms in Northern Missouri and the prairie grass program is still in an early phase.
