Pakistan is blessed with enormous renewable energy resources. Nevertheless, against its abundant potential, the continuous reliance on large base-load power plants and the existing remarkably low share of renewables in the energy mix–four per cent of installed capacity and two per cent of power generation–is often intriguing for observers.
While there are several challenges to the continued development of renewable energy projects, perhaps the most limiting factors remain the technical ability to absorb the intermittent and stochastic weather-determined output of renewable energy sources such as wind and solar. To apprehend the full spectrum of variable renewable energy (VRE) integration, it is very important to understand the nature of its intermittent output, which is fundamentally different from controllable production units. The output of a solar electric system resembles a bell-shaped curve with peak output centred at mid-day and the spread depending on the day hours. On the same lines, wind output keeps fluctuating with wind conditions. In the jargon, these resources are “non-dispatchable,” i.e. producing energy only when the sun is shining or the wind is blowing. Resultantly, they pose a range of technical challenges to grid operators making its accommodation difficult in the existing grids – initially designed to comply with less or non-variable energy sources.
Corresponding to these challenges, power system flexibility- “the extent to which a power system can modify electricity production or consumption in response to variability, expected or otherwise”- remains the key driver of VRE.
Power system flexibility remains the key driver of Variable Renewable Energy
Grid operators do not control these sources rather accommodate it – which requires some agility. Varying at all-time scales, prior information on VRE production becomes necessary. ‘Forecasting’ is emerging an indispensable source of information for mitigating the stated uncertainties surrounding VRE supplies. Technology has always played an important role in the past for reading electric loads. Its introduction in VRE, however, is recent. Many advanced forecast projects such as cloud-based computing mathematical models and high-resolution weather forecasts are currently being piloted for improved visibility of supplies over a timeframe of seconds to minutes, hours, days and seasons. Despite these technologies, VRE output cannot be predicted with perfect accuracy excess reserves. For adjustment of these fluctuating loads, grid operators have to keep excess reserve running together with rapid response in terms of start-up time, ramp up -ramp down of output and minimum generation level of the plants for following the netload.
In terms of integrating higher shares of VRE, the power sector of Pakistan currently has several limitations. The country lacks renewable energy forecasting techniques. The existing monitoring and dispatch system i.e. Supervisory Control & Data Acquisition (SCADA) is not even fully functional- resulting in insufficient monitoring of even existing generation facilities. Limited reserve capacity and inflexible operation of conventional plants are few other barriers. Further, the more integrated a grid is, the more likely it is that the sun is shining or the wind is blowing somewhere within the geographical boundaries. With a very isolated grid standing and cross-border integration only with Iran, Pakistan could also not gain the benefits of this economically efficient geographic smoothing effect. Though many plans were set afoot for transmission interconnections with neighbouring countries including China, Central Asia and India yet so far CASA 1000 is the only actively pursued project between Afghanistan, the Kyrgyz Republic, Pakistan and Tajikistan. Lastly, the transmission network in Pakistan is hugely inefficient, marred not only by high losses but also severe capacity constraints- where investment in transmission has failed to keep pace with generation hence barely absorbing the growth in the latter. These constraints collectively have handicapped Pakistan’s renewable energy trajectory.
The bottom-line is -building flexibility in the system. We can upscale as much VRE as we want, conditional upon overcoming these grid-integration challenges. So, it is time to start taking variability seriously. Flexibility needs in the power sector will need coordinated orchestration of planning across the entire chain of power system ranging from generation to more resilient transmission and distribution systems including demand-side management. Improved planning and coordination only could potentially unlock the pathway to energy transition and herald the end of fossil fuel dominance.
The writer is a research officer at the Institute of Policy Studies, Islamabad