Burning liquid ammonia power

IHI Corporation announced on June 16 that it has achieved CO2-free power generation by using only liquid ammonia (NH3) as fuel in its 2,000kW-class gas turbine, and has succeeded in reducing non-CO2 greenhouse gases such as nitrous oxide (N2O) generated during combustion by more than 99%. 

This research and development was carried out with the support of the New Energy and Industrial Technology Development Organization (NEDO)'s Green Innovation Fund project "Fuel ammonia supply chain construction" (scheduled for FY2021~2030, budget 59.8 billion yen). 

Since NH3 does not contain carbon (C), there is no concern about emitting CO2 during combustion. By improving and adjusting existing power generation facilities, it can be used as fuel, and although it is a gas at atmospheric pressure and room temperature, it can liquefy at -33°C, and if a pressure of just under 8.5 atm is applied, it can be liquefied at room temperature (20°C). Compared to hydrogen, a CO2-free fuel that is also a gas at atmospheric pressure and room temperature, will require less energy to liquefy, store, and transport. 

However, liquid ammonia has a problem in that it is less flammable than natural gas or ammonia gas and is less likely to burn. Moreover, even if there is no concern about CO2 emissions, if combustion does not go well, there is a risk of emitting N 2 O, which has an extremely strong greenhouse effect of about 300 times that of CO 2. Increasing the co-firing rate of ammonia also increases the risk, so stable ammonia combustion and N 2 in exhaust gas is important in reducing O emissions. 

IHI's combustion method using liquid ammonia is to spray liquid ammonia directly into the combustor of a gas turbine. The reason is that it has advantages for wide implementation, such as simplification and improved controllability of the supply system from storage tanks to gas turbines. 

By using this method, it has been confirmed that N2O is generated when operating at a high ammonia co-firing rate of more than 70%. In other words, if the ammonia co-firing rate was to be further improved, it would lead in to zero CO2 emissions and greenhouse gases. 

Under such circumstances, IHI's Yokohama Plant's 2,000kW-class gas turbine was tested with a newly developed combustor. As a result, the high ammonia co-firing rate of 70~100%, led to  a greenhouse gas reduction rate of 99% or more.  It was demonstrated that 2000kW-class power generation can be achieved by burning only liquid ammonia. 

In future developments, the company will further reduce nitrogen oxides (NOx) other than N2O, improve operability, evaluate durability over a long period of time, and promote efforts toward the practical application of 100% liquid ammonia combustion gas turbines by 2025.