Daily Times

For a host of reasons, solar and wind technologies as alternative sources of electricity are destined to grow in Pakistan in the coming years. Their march seems unstoppable now and resisting it will be neither possible nor wise. The real challenge, however, will be to steer their adoption in ways that can secure the true benefits these technologies are capable of providing to our economy and society. Though utility-scale deployment of these technologies, and in particular those based on photovoltaic effect, is not the only avenue for their uptake, the discussion below will content with identifying some major issues which, if not resolved timely, can undermine their optimal deployment in the electricity grid.

Electricity supply industry (ESI) globally has evolved around tightly-synchronized and controlled alternating current (ac) power generation, transmission, and distribution systems. Power system operators work diligently and round-the-clock to maintain a perfect balance between the demand and supply of electricity. Any major contingency in any part of the system can disturb this delicate balance. If not corrected within split seconds, this unbalance can easily spread into the system and can lead to major blackouts, causing enormous losses to economy and serious disruption to society.

Electric utilities always maintain some reserve “capacity” in their systems to serve demand that varies randomly over time. This is necessary because like all physical systems the plants, networks, and equipment in the electricity grid also require periodic maintenance or could be “down” when needed. Utilities also maintain reasonable stocks of primary fuels to serve the forecast “energy” demand in their systems (electricity consumed in consumer loads) to hedge against risks of fuel supply disruptions. The above situation changes when renewable plants join the grid.

For conventional plants, the capacity is constrained only by the plants’ being on maintenance or when they are “down”. Other than cost, fuel supplies are normally not constrained. Still, plants are sometimes designed to operate on multiple fuels to alleviate fuel supply risks. Unlike conventional plants, renewables rely exclusively on natural energy flows such as solar radiation and wind. These flows are abundant and free in nature, but their availability is “intermittent” and “variable”. The availability of renewable plantsis, therefore, constrained, more by resource limitations than by their physical unavailability. Solar plants are further constrained due to sunlight’s availability during daytimesonly.

When added to the grid in any significant proportion (often termed as grid “penetration”), renewables pose many new questions for system planners and operators. For instance, how much these plants will contribute to system capacity, if any, to ensure continued reliability of service? How to estimate thesecontributions? How to build the necessary flexibility in the grid to handle the frequent cycling and ramping duties their presence imposes on other plants which are not designed for such duties? How to quantify their costs and benefits in the grid which are often not reducible to monetary terms? And, how to incorporate these costs and benefits in the techno-economic evaluations in system and operational planning tools and practices which have evolved mostly around central-station conventional power generation?

Answers to the above issues depend a great deal on the existing and future grid structure, patterns of electricity demand in various parts of the country, the spatial and temporal distribution of the renewable resources under consideration (solar, wind, or both) in these areas, and the climatic and geographical conditions at sites where these plants are to be developed. These are complex issues and there are no easy answers to them. Nevertheless, these issues must be handled upfront as some of these can compromise renewables’ ability in delivering their full benefits to our country.

We will need adopt appropriate strategies to ensure that our nation, in its quest to eliminate dependence on imported fossil fuels, does not end up into a new import dependency

The purpose of raising these issues isn’t to discourage decision-makers from seeking higher shares of renewable generation in the local grid. It’s only to draw their attention towards these important aspects which, if not addressed timely, can seriously hamper realizing of an otherwise laudable goal of scaling up renewable generation in the country. An aggressive effort will be needed to explore the nature and extent of the above issues and also to devise a proper strategy to address these challenges in parallel with the deployment of renewable power generation schemes in the country.

Though we currently see some news making rounds in the media that our government will encourage developers to invest in hybrid renewable generation schemes (wind plants together with solar) at some sites, we hardly hear any suggestions on promoting their hybrid development with some form of backup storage. This is a serious omission as storage (on-site, off-site, or remote) can be a natural complement to renewable generation plants in covering their intermittency and variability limitations.

Many of the “ifs” and “buts” currently hovering around renewables, including those raised in the previous paragraphs, would evaporate into thin air if we could find some practicable and cost-effective means of energy storage in the system. Many such options already exist and some new ones are currently under development. Their technical and economic feasibility in Pakistan, however, will have to explored, especially as an integral part of the renewable development and deployment plans.

A highly-promising option may be “pumped hydroelectric storage (PHES)” schemes which operate as a regular hydroelectric generation facility during peak demand periods but work as a mechanical pump to push water from a lower reservoir to one at a higher elevation during off-peak periods using comparatively cheaper electricity from the plants which may otherwise remain idle or under-utilized.

Even though such arrangements can be provided even at some existing hydroelectric plants, their true benefit will come only if some natural terrains in Balochistan can be further developed into PHES schemes. These facilities can provide storage to renewable power generation not only in that province but can also be used to channel excess generation from renewable resource rich areas in other southern regions of the country including Gharo-Jhimpirwind corridor in Sindh. Even if PHES schemes entail somewhat higher investment costs, our government should prefer them over other storage options since their payoffs will continue flowing to our future generations for which they will be thankful to their ancestors.

Another hardly discussed but critical aspect of higher shares of renewable power generation technologies is the access to and continued availability of materials that are used in manufacturing of both wind generators and photovoltaic panels and the “balance of system” components used with them. Some of these materials are scarce in nature and their distribution in the world is also highly uneven. We will need to carefully study this aspect also and adopt appropriate strategies to ensure that our nation, in its quest to eliminate dependence on imported fossil fuels, does not end up into a new import dependency.

Benjamin Franklin had once noted, “Failing to prepare is preparing to fail.” It will not be too early for our policy- and decision-makers to be concerned about such issues and start preparing to circumvent the potential traps and dependencies. Resolving these issues will obviously require rigorous studies and investigation and, therefore, will need time, effort, and funding. But the benefits of such studies, research, planning, and informed decision-making will be worth all their costs; in fact, many times over.

The writer is a freelance consultant specializing in sustainable energy system planning and development