Daily Times

Pakistan’s decision makers seem to have just jumped into the VRE bandwagon, mostly in their enthusiasm to go along with the tide, without realizing that the road ahead will be not only bumpy and full of potholes but will also test to limits the competence and skills of the drivers leading the journey. Passengers (aka “consumers”), therefore, should expect anything but a smooth and trouble-free ride.

It has become fashionable in Pakistan these days to advocate going all out for renewable energy generation (often also termed as variable renewable energy, “VRE”, due to the uncertain and variable nature of the primary resource, solar or wind, on which such generation depends). One, therefore, risks the ire of experts and business interests if s/he dares to raise any concerns about the viability or complexity of integrating high shares of VRE schemes with the power grid.

Admittedly, VREs have come a long way in the past couple of decades. From their status in the 1980s as a set of exotic alternatives, mainly of academic interest, to conventional generation technologies, VREs have graduated into a formidable force and are now in a head-to-head competition with their conventional counterparts. Despite their coming of age, however, VREs are not a panacea for every ill that currently ails our power sector.

Unlike the conventional power generation technologies that can be sited virtually anywhere in the country provided the fuel transport costs to that particular site or electricity transmission costs from there to the nearest load center can be justified (the only other issue being the availability of a large water body around for cooling), the siting of VREs requires a carefully-studied match between the primary resource availability at that site, ambient operating conditions, and the pattern of electricity demand on or near that site.

VREs can also be a stepping stone to lead our country from its present unsustainable power supply systems and practices to more secure, economic, and sustainable energy supplies for our people in the future

Any effort to promote VREs in the country at any significant scale must answer at least six questions. First, what would be the best deployment mode for VREs? Second, what would be their optimum uptake level, in the short-, medium-, and long-term? Third, what would be the benefits and costs of VRE deployment and their viability against conventional options? Fourth, how friendly or hostile the hosting system is for their painless uptake? Fifth, what relief (stress) VREs would provide to (impose on) the hosting system and how can this relief (stress) be maximized (minimized)? And, sixth, what role they would play in contributing to the strategic objectives of the country?

Under the right policy support and a carefully-crafted strategic program, VREs can undoubtedly provide invaluable benefits to our country. But a program based mostly on whims and mindless replication of international trends could lead to not only missing out on many of the opportunities VREs possess but could even hurt their future prospects in the country.

Arguably, it’s highly desirable to shift our country’s reliance on imported and polluting fuels to indigenous, renewable, and eco-friendly sources of energy like solar and wind. Their deployment in the country via the power grid is also equally desirable as it will provide a convenient and established avenue for their quicker adoption. However, power grid is not the only, or the most viable, avenue for this purpose. This is particularly true for schemes that are based on solar resource which, even though ubiquitous, is diffused and scattered, and is restricted to daytimes only.

Grid-connected VRE schemes based on solar energy alone could be built on harnessing the heat content in the solar like the “concentrated solar power (CSP)” systems to generate electricity indirectly or converting the light energy in it directly into electricity through photovoltaic (PV) conversion technologies, both requiring substantially different approaches to their grid integration, interface technologies, system considerations, and ultimately widely different financial implications.

At low levels (often termed “grid penetration”) not exceeding 4 or 5 percent, VREs can be integrated into the grid without much problem as power grids are routinely designed to accommodate randomness of consumer demand, vagaries of weather, and risks of unexpected plant and equipment outages. But as their shares in the grid increase, their value addition to the grid starts to taper off, as output from VREs defies control and their presence in the grid becomes more taxing on the rest of the system which is now called in for extra duty to cover VREs’ uncertainty and variability.

Promotion of VREs via targets like “20% by 2025” and “30% by 2030” is problematic because they lack clarity and concreteness as to what exactly is being targeted. Is it 20 or 30 percent of energy generation, installed capacity, or peak demand in 2025 or 2030? This knowledge is necessary as each will have significantly different technical and financial implications. Such targets are generally fixed after carrying out rigorous grid impact studies to ensure that the hosting grid is, or will be, ready with the requisite capabilities by the time VREs are actually deployed.

Out of the sheer size and complexity of the power system expansion problem, consumer demand for a control area, region, or country is aggregated and the same is done for the supply resources on a planner’s platter to serve the forecast demand at a pre-set reliability target at least cost to that system, region, or country. Once this is done, some plausible configurations of the T&D options are studied to fine tune the previously selected generation portfolio before rolling out the formal plan.

When VREs are added to the grid at significant proportions, the above approach to system optimization has to be turned on its head. The diffused, scattered, and distributed nature of renewable resources makes it imperative that the optimization exercise be started from the bottom and gradually built towards the top, incorporating along the way the key characteristics of the resource at a site, expected operating conditions, and the patterns of both existing and forecast demand in that area.

Unfortunately, most commercial system planning tools are not designed for such disaggregated planning nor are most planners properly trained for it. Many of the benefits the VREs can provide to a system or country defy easy monetizing and, therefore, are difficult to capture and incorporate within these planning tools, often compelling planners to use approximations or ignore these benefits altogether thus providing a distorted outlook of the future, largely biased against the VREs.

The hosting power grids are traditionally designed for duties based on the established technical and economic characteristics of conventional power generation technologies, mostly to handle random variations in demand and technology-oriented outages of the generation and T&D systems, with no or very little consideration for uncertainty and variability of the underlying primary resources.

To accommodate VREs, the grid requires considerable flexibility by retrofitting the conventional generators, enhancing, augmenting, or modernizing the T&D networks, including operation and control systems and protocols, and the protection schemes and fault handling equipment to effectively deal with normal, contingency, and emergency conditions. Obviously, all these efforts add considerable technical complexity to the existing grid and also entail substantial additional costs which cannot be ignored.

Efforts to promote VREs in Pakistan must continue as it’s the need of the time. VREs can also be a stepping stone to lead our country from its present unsustainable power supply systems and practices to more secure, economic, and sustainable energy supplies for our people in the future. However, these efforts and policies must be based on proper background studies and not merely on whims or just because every other country around us is also doing it.

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