What if both the water and carbon dioxide (CO2) produced from a vehicle’s exhaust system could be captured and used for growing food? Repurposing these two wasted products would be a game changer for reducing the carbon footprint of roadway traffic and helping the agricultural industry feed a growing human population.
Three faculty members at Texas A&M University, Maria Barrufet, Elena Castell-Perez and Rosana Moreira, have written a white paper reporting their initial analysis and published it in hopes of obtaining the funding needed for doing formal, multidisciplinary research on the project.
“I started reading the related literature and did simulations of what was possible,” said Barrufet, professor and Baker Hughes Endowed Chair in the Harold Vance Department of Petroleum Engineering. “This is entirely realistic. Several proposals have already been written for large trucks and marine vehicle applications, but nothing has been implemented yet. And we are the first to think of a passenger car engine.”
The impact could be enormous. In 2019, the number of vehicles estimated to be in use around the world was 1.4 billion. An average passenger car in operation can emit about 5 U.S. tons (approximately 4.6 metric tons) of CO2 per year, meaning a significant amount of greenhouse gas is going into the environment. One car’s fuel combustion also creates a large amount of water per year—about 5,547 gallons (approximately 21,000 liters).
Castell-Perez and Moreira, both professors in the Department of Biological and Agricultural Engineering, know this wasted CO2 and water could be put to good use, especially in cities. Recent expansions in U.S. urban agriculture rely on industrial greenhouses, which use an artificially enriched atmosphere containing up to three times the amount of CO2 in normal air to improve plant health and harvests. These urban farms would greatly benefit from a steady source of free, reclaimed CO2 and water as they currently purchase and use almost 5 pounds (over 2 kg) of CO2 and nearly six gallons (22 liters) of water to grow just over two pounds (1 kg) of produce. And these numbers don’t include the water and CO2 needed for post-harvest food processing and dense-phase pasteurization.
The three faculty members outlined how the integrated device could work. Heat from the engine could power an organic Rankine cycle (ORC) system, essentially a small, closed unit containing a turbine, heat exchangers, condenser and feed pump that works like an old-fashioned steam engine but on a much smaller scale, and with far less heat needed to produce electricity….