Our research in science related to green technology involves new methods and techniques to address climate-change emissions from New Zealand’s productive and waste management sectors. Currently, we are directly addressing methane, carbon dioxide, and nitrous oxide.

Methane emissions contribute significantly to short- to medium-term climate change.

The United Nations Climate and Clean Air Coalition says “cutting methane emissions 45% by 2030 could avoid 0.3°C warming by 2040”. New Zealand has legislated that biogenic methane emissions must be reduced by 10% by 2030 and 24-47% by 2050 (relative to 2017 levels).

Lincoln Agritech is working on the methane problem by developing new ways to neutralise methane after ruminant animals have generated it. This is highly challenging, as the reaction must operate at low methane levels (well below the combustion limit) with very low input energy. However, we have made significant progress with an electrochemical solution and are currently moving from a science discovery phase towards a viable prototype. The New Zealand Agricultural Greenhouse Gas Research Centre has funded this work.

Carbon dioxide sequestration

Decarbonisation of agriculture, industry, transport, and energy is critical to minimise global warming in the decades to come. New Zealand has committed to be carbon zero by 2050 to help achieve the Paris target of a maximum 1.5deg C temperature rise. All global climate models scenarios which can achieve this target require negative emission technology (NET), also called direct air capture (DAC), of carbon dioxide. NET draws carbon dioxide from the air at ambient conditions (approximately 420ppm) and sequesters the carbon in a form that cannot readily be released back into the atmosphere. Typically, the carbon dioxide is converted to calcium carbonate or limestone, which stores carbon for many thousands of years (unlike trees).

We are exploring the use of advanced electrochemistry methods to capture and convert carbon dioxide from seawater into various carbonates. Since the ocean and atmosphere are in equilibrium, the net effect is to also reduce atmospheric levels of carbon dioxide. Although our experiments have been relatively small scale (producing only grams of carbonate) the energy consumption required is low. We are also investigating how to scale up these methods to provide a low-energy means for removing carbon from the short-term carbon cycle.

Nitrous oxide

Nitrous oxide, N2O, is the third most important greenhouse gas in the world and accounts for around 10% of New Zealand’s total emissions. However, it has an oversized effect for two main reasons

  1. Each molecule causes approximately 265 time more warming than carbon dioxide (over 100 years).
  2. The lifetime of N2O is around 115 years, on average, making its effects relatively long-lasting.

New Zealand’s N2O emissions are mainly from agriculture and caused by microbiological processes in the soil that convert ammonium ions from animal waste (especially urine) and dissolved fertiliser into nitrates, NO3. Later in the nitrate cycle, these ions are denitrified, in part to N2O. Nitrification inhibitors, such as those developed by Lincoln University, interrupt the nitrogen cycle by inhibiting the production of nitrate ions and N2O, but still allowing plants to uptake the required ammonium ions.

We are planning research and trials of both wide-area gas monitoring and, potentially, electrochemical destruction of N2O.

Contact: David Rankin for all GreenTech