Imagine using geothermal heat from oil and gas wells to offset the burning of natural gas for domestic and commercial space heating.
That is a concept Rachel Scharein and her fellow fourth-year classmates investigated as part of a University of Calgary project course in sustainable energy, environment and economy.
“You could either use actual fluid that is coming out of the well itself, or you could actually pump a fluid down into the well — ethylene glycol is what we were looking at,” the 27-year-old mechanical engineering student told the Daily Oil Bulletin.
“You have a piping system that will distribute it to the homes, and then through a heat exchanger you would use it to heat up the homes.”
Scharein and her team presented one of 10 projects on display Monday afternoon at the U of C’s downtown Calgary campus as part of a cross-faculty initiative for fourth-year energy specialization undergraduate students.
About 80 per cent of the students in the course study engineering and about 20 per cent are in the natural sciences.
“This is a joint event between my research program, which is the Canadian Energy Systems Analysis Research (CESAR) initiative at the University of Calgary, and a class I teach — a fourth year capstone project in the faculty of science and engineering,” said David Layzell, CESAR director and biological sciences professor.
“In September, I showed the students 12 different projects of different ideas of how the energy systems could be transformed to make them more sustainable and address the climate change challenge. They voted on the ones they find most interesting. Based on what they voted for, I assigned them into the projects.”
Eric Donovan, associate dean of research in the Faculty of Science at the U of C, said Layzell’s class allows fourth-year students to venture out of their “disciplinary silos,” helping prepare them for their careers by delving into very topical, interdisciplinary matters.
“This capstone course focuses on what I would call a ‘grand challenge for society,’ which is how to come to terms with our environmental and energy issues looking into the future.”
Alberta energy future scenarios explored the geothermal potential in Alberta, cement plant carbon capture and electricity production, fuel from biomass residues, decarbonizing freight transport, replacing conventional home heating with natural gas combined heat and power, methods of reducing home heating emissions by 95 per cent, electrifying transportation, autonomous vehicles, and the impacts high-density community lifestyles have on emissions.
Trevor Pickett and his group considered heat recovery from depleted SAGD reservoirs to generate green electricity. The group concluded that electricity generated from depleted SAGD heat recovery could reduce emissions associated with electricity use in the SAGD sector by up to 28 per cent.
“When the SAGD facilities stop producing oil, there is heat left over in that reservoir, and so we were looking to recover some of that to generate GHG-free electricity,” he said, adding the method produces power using an organic Rankine cycle (ORC). “That [electricity] could be used on site, and it could also be exported back onto the grid.”
However, noted the 22-year-old chemical engineering student, while anything that creates electricity has value, the method is not without its drawbacks. For example, ORC efficiency is low — below 20 per cent — and it decreases as the water temperature decreases.
“Unfortunately, as a group we were slightly disappointed with the results, simply because the energy used to generate steam for oil production just trumps all the recovery we could do — the emissions from generating the steam are so much higher than the actual electricity used. While we are only recovering a bit of this, though, the economics surprisingly don’t look too bad.”
According to Layzell, proponents of some technological solution in the energy and environmental space typically only convey what is positive in their solutions. A benefit of his class is that students delve into the possibilities of a particular technology, considering a full lifecycle analysis of all implications, both good and bad.
“Our purpose for it is to inform policy and investment decisions by government and industry. We are hoping to identify the issues around looking at particular technologies, and informing governments whether they should be investing or not in this or that, and informing industry in identifying [research and development] priorities.”
Scharein and her group found the wells’ temperatures to be a limitation for the geothermal potential of direct heat from oil and gas wells, as is the amount of fluid actually flowing through the wells. Distribution systems likely would cost a lot for this solution, she noted, and it would probably be more easily deployed in new homes as part of communities built for geothermal heating systems, rather than retrofitting current homes.
“A lot of oil and gas wells in Alberta are below 80 C, and so it limits how far we can pump the heat, as well as the cost of the piping system,” Scharein said, adding that it would be interesting to see geothermal heating systems going into industrial applications such as greenhouses and warehouses, which could be better options than trying to place houses near this particular geothermal heat source. “You don’t want a lot of residential homes near oil and gas wells.”
In January, CESAR will release blogs that look in more depth at the individual projects presented on Monday afternoon. Free copies of the students’ posters can be downloaded at cesarnet.ca.