MICROALGAE FOR ENERGY PRODUCTION AND NUTRIENT RECYCLING Nicola

MICROALGAE FOR ENERGY PRODUCTION AND NUTRIENT RECYCLING Nicola Wood, Student Sustainability Conference, 29 th March 2019

Source: UN Sustainable development Goals

ENERGY • Fossil fuels are estimated to account for 78% of global energy consumption as late as 2040 (IEO, 2016). • Global energy demand is set to rise by 50% between 2012 – 2040 • Oil, gas and coal are predicted to run out as early as 2066, 2068 and 2126 respectively • Atmospheric greenhouse gas levels are at a record high • Increasing occurrence of weather extremes are believed to be connected with increasing atmospheric CO 2 • Global sea level rises by approximately 2. 0 mm per year Sources: https: //oceantoday. noaa. gov/happennowarcticseaice/; National Oceanic and Atmospheric Administration

FOOD • Sustainable food production requires arable land large quantities of clean water and fertiliser. • The Haber-Bosch process to create ammonia from atmospheric nitrogen and hydrogen requires 1 -2% of all global energy and requires approximately 2 L fossil fuel to produce 1 kg of nitrogen for fertiliser. • World consumption of P 2 O 5 is set to rise by 10% in the next 4 years. • Phosphate is not an infinite source! P

WORLD PHOSPHATE RESERVES Sources: US Geological Survey, 2014; http: //www. potashcorp. com/overview/nutrients/phosphate/overview/world-phosphate-rock-reserves; Source: http: //www. indexmundi. com/commodities/? commodity=rock-phosphate&months=180

WATER • An average city of 500, 000 inhabitants produces approximately 85, 000 tonnes of municipal wastewater each day all of which needs to be treated. • Leeds produces approximately 130, 000 tonnes per day • Despite our reliance on nutrients for fertiliser, most of the nutrients we currently use end up lost through wastewater treatment processes

2 harnessed, total human energy demand could be satisfied by an area equivalent to 0. 07% of the earth’s land surface CO 2 CO • BIOENERGY-THE SOLUTION TO OUR ENERGY PROBLEMS? If 10% of the sun’s energy reaching earth could be • But biomass production for energy is severely limited by the availability of land fresh water. The ‘Food vs. Fuel Debate’

MICROALGAE • Diverse group of eukaryotic single cell organisms. • Can grow efficiently on non-arable land – do not compete with food for land • Do not require a fresh water supply • Increased efficiency of energy to biomass due to their simple structure • Much greater oil yields than most plants • Neutral lipids, triacyglcerols (more commonly referred to as oils) are the starting product for biodiesels. • TAGs can be turned into biodiesel via a transesterification process and used similarly to regular diesel fuel.

BUT… • Current fuel prices at pump are approximately $0. 60 -2. 30 across the world • In order to be economically viable, microalgal biodiesel must therefore be comparable in cost. • The cost of microalgal biodiesel need to fall by approximately 5 -7 times current costs SO… • Combine microalgae with wastewater treatment • Microalgae have naturally high N (~10%) and P (~1%) contents meaning they offer the ability to remove high quantities of nutrients from waste streams Source: Delrue et al 2012

THE CLOSED LOOP CYCLE

SO, WHERE ARE WE UP TO? • Microalgae grow well in a variety of wastewaters to high biomass yields • Microalgae can successfully remove almost all N from wastewater streams. • But, the only known triggers of oil accumulation are from high stress leading to cessation of growth and limited biomass yields • The conditions needed to optimise phosphorous accumulation are poorly understood

A COMPROMISE Biomass • Optimised by high carbon, nitrogen and phosphorus supply Oil Phosphorous • Optimised by nitrogen starvation and high carbon availability • Optimised by high phosphorus concentration with/without pre -starvation period

WHAT NEXT? • Genetic modifications • Looking at lesser studied triggers for oil accumulation • • p. H Sodium bicarbonate addition Phosphorous starvation The effect of different nitrogen sources

Thank you for your attention Any Questions?