In our group, we use energy systems models to understand how to get to net zero. In general, energy systems modelling is a method used to represent, simulate and analyse energy systems and their constituent components. The models are then used to optimise some aspect of the system performance. This could be a total operating cost, or total emissions or maximising a metric for reliability. Since the energy system is a huge, incredibly complicated system, the models must make many assumptions. Our approaches to energy system modelling include aspects of engineering, data analysis, economics and environmental science.

Modelling the power system is a subsector of energy systems modelling. In power sector modelling, only the electricity system is modelled. Although electricity is a relatively small part of the energy system, it is crucially important since electricity is considered to be the key in the transition to sustainable energy systems. Most decarbonistion strategies globally rely on electrifying many of the other sectors in the energy system, such as transport and heating. The primary reason for this is that electricity is a versitile form of energy which we can provide with minimal carbon emissions, for example by using wind, solar or nuclear power. Therefore, electricity is the focal point for models that aim to assess and optimise low carbon energy solutions. The general framework of a power system model is shown in Fig. 1.

In electricity systems modelling, the various components that consititute the system are simulated, including power generation (i.e. wind turbines, combined cycle gas plants, nuclear plants), transmission and distribution (i.e. the wires and their capacities), energy storage (i.e. pumped hydroelectric systems, hydrogen) and the demand (i.e. the end user consumption of electricity). In the UK, our biggest uses of energy are for heating (mostly gas), transport (mostly fossil fuels) and for electricity. Fig. 2 below uses data from Dr Grant Wilson's work, illustrating the current UK electric, gas (at the local distribution level) and transport energy demands. While electricity is the smallest component, methods for increasing energy security and decreasing carbon emissions rely on replacing much of the gas (used for heating) and fuels (used for transport) with electricity. This also has benefits in terms of reducing overall energy consumption since heat pumps are more efficient (in energy terms) than gas boilers and EVs are also more efficient than IC engines.

Most scenarios which reduce our gas and oil reliance in 2050 include massive build outs of renewable generation. For example, national grid's system-led transition scenario (from the future of energy scenarios) involves 190 GW of wind and 150 GW of solar generation. This yields considerable challenges with balancing the demand and supply, likely necessitating considerable increases in system flexibility (the ability to shift electrical demand from one period to another) and huge deployments of grid scale storage. Energy systems models allow us to put numbers on the amount of energy storage required, or how much flexible demand we need in order to avoid system failures.