Scientists have measured big increases in the amount of methane, a powerful global warming gas, entering the atmosphere. Methane has more than 80 times the warming power of carbon dioxide over the first 20 years after it reaches the atmosphere according to the Intergovernmental Panel on Climate Change. Our Methane Monitoring System will support the industry in reducing methane emissions from oil and gas operations. This is among the most cost-effective and impactful actions that can be taken to achieve global climate goals. Improved measurement and reporting can in turn lead to more efficient regulatory interventions. Natural gas leaks can be highly episodic in nature and infrequent monitoring can easily miss leaks. Many existing monitoring systems would miss sporadic leaks since they are used for spot checks due to their cost and requirement for trained users. The devices we are developing for methane detection will be optimised to provide continuous monitoring over a large area, making them ideal for assessing and monitoring the rate and location of fugitive emissions of natural gas. Our devices will consist of a fully autonomous observational network of sensors, providing low latency continuous monitoring. By continually monitoring the emissions we are not only able to detect infrequent and sporadic events, we can gain information on background fluctuations and establish algorithms to eliminate false positives. Existing gas sensing technologies are either prohibitively expensive or have low sensitivity, short lifetime, or do not give sufficient discrimination against other gasses or even water vapour. Our optical technology is based on a fundamental re-design of the optical system, where low power consumption for year long field use becomes possible. We are developing a prototype to demonstrate proof of principle in order to gain acceptance in the industry. We are optimising the semiconductor light source, sampling volume and detector, to maximise battery life and performance designed to meets the requirements of 'Best available techniques not entailing excessive cost' (BATNEEC). This ensures our systems meet requirements under UK environment protection legislation.