Renewable natural gas is among the newest low- or no-carbon fuels made from agricultural products that are generating attention from power utilities, investors and governments.
Actually, capturing and using methane, or biogas, produced from anaerobic digestion in livestock manure ponds has been around for a long time in Europe and developing countries
In the early 2000s, the Iron Creek Hutterite colony near Viking, Alta., captured methane from manure produced by its hogs and chickens to produce heat and electricity. The farm used some of the electricity and the rest was sold to the provincial grid.
Now, investors and natural gas companies are looking at much bigger projects.
The idea is not to burn the gas to make electricity and heat, but to clean it up and put it into the pipeline systems that carry natural gas into homes. It would lower the carbon intensity of conventional natural gas.
The feedstocks for biogas are widening from just manure to include grain and other materials, creating new domestic markets and financial benefits for farmers. Feedstock can also come from forestry waste, landfills and sewage treatment plants.
Also, it is becoming possible for facilities to produce several types of renewable fuel and valuable byproducts.
Canada’s natural gas utilities have an aspirational target of five percent renewable natural gas, or RNG, blended into natural gas streams by 2025 and 10 percent by 2030, according to the Canadian Gas Association.
If that 10 percent is achieved, it would lower greenhouse gas emissions by 24 megatons a year, the equivalent of removing 5.2 million gasoline-fuelled passenger cars from the road, according to the association.
Such a lofty goal is ambitious.
However, there are interesting developments in the works, encouraged by incentives such as Canada’s Clean Fuels Standards and Clean Technology investment tax credits. There are even more valuable tax credits and incentives in the U.S. Inflation Reduction Act.
Future Energy Park in southeast Calgary is advanced by Green Impact Partners, a Calgary headquartered company that also has RNG projects in Colorado and Iowa.
Construction of Future Energy Park is expected to begin this year and the plan for the $1.2 billion facility is to buy 900,000 tonnes of weather-damaged non-food wheat to produce more than 300 million litres of ethanol.
To give a comparison, that would be twice the production of the Co-op Ethanol Complex, formerly called Terra Grain, at Belle Plaine, Sask.
At the Future Energy Park facility, the material left over from ethanol production would be put in a tank for anaerobic digestion, creating 3.5 million MMBtu, or roughly 3.5 billion cubic feet of RNG, clean enough to put in a natural gas pipeline. The final byproduct is 350,000 tonnes of distillers grain for livestock feed.
The carbon dioxide created by the plant would be captured and compressed for sequestration, ultimately meaning the plant will be carbon negative.
Green Impact Partners believes there is enough low grade wheat produced on the Canadian Prairies to fuel another two such plants in the future.
Another unusual project is located at a former DuPont cellulosic ethanol plant in Iowa.
A story by Chris Clayton of DTN says that Verbio North America Corp., a subsidiary of a German firm, bought the plant to use Verbio’s technology to make RNG from corn stover — the leaves, stalks and cobs left after the crop is harvested.
It buys 100,000 tons of stover from local farmers. It chops it into a powder that is put into tanks fed with bacteria from cattle manure. The bacteria break down the material, creating biogas that is cleaned and fed directly into the Alliant Energy natural gas pipeline for distribution across the U.S.
The material left from the process is made into fertilizer and soil conditioners. The plant is undergoing further modifications to also produce corn ethanol.
Arguably, renewable natural gas has strong green credentials, but it has its critics.
FortisBC, a natural gas utility in B.C., is aiming for 15 percent of its natural gas supply to come from renewable sources by 2030, but it is being sued for false advertising.
FortisBC now buys RNG produced in places such as Pennsylvania and consumed there, but wants the credit to be applied to its own conventional, fossil fuel natural gas produced in B.C.
Critics also note RNG, like conventional natural gas methane, is a powerful greenhouse gas if released into the atmosphere, so any leakage would be bad.
Critics say RNG only extends the use of natural gas. They say it would be better if people heated their homes with heat pumps powered by electricity produced from renewable sources such as hydro, wind or solar.
Source: Producer