Due to the accelerated global economic growth, energy consumption is increasing exponentially on a yearly basis. At the same time, the onslaught of greenhouse gases (GHGs) caused by the use of fossil-fuel-based energy technologies is creating numerous environmental hazards. With this looming threat, renewable energy (RE) is becoming the most-sought-after resource, and harnessing it has immense potential for generating eco- benign green energy. Here, Dr Om Prakash Nangia says that for climate change mitigation, the seamless harvesting of solar PV in combination with wind technology as a hybrid system is proving to be a key development. The hybrid solar–wind system will make economic sense in aiding growing economies with clean energy transformation to achieve development and climate goals.

Over the last decade, solar has been the single-largest contributor to green energy generation: it has zero emissions due to huge technological advancements in the field. Similarly, wind energy, a widely distributed renewable resource, produces clean and economical electric power with zero emissions. However, the use of solar and wind technologies is beset with challenges despite the sun and the wind being infinite sources of energy: the main challenge is their intermittent nature and the lack of dispatch ability in keeping the electric grid stable. It is reported that fluctuations in power output can negatively impact amortization periods for system owners. However, with the deployment of hybrid RE power generation systems that are backed with energy storage, the seamless harvesting of solar PV in combination with wind technology is the key to challenge generation variability and effective mitigation of climate change.

Overall, clean energy is expected to experience strong growth in pushing the markets in countries where economic policies provide incentives towards achieving the goals set in the Paris conference on climate change (UNFCCC: COP21, December 2015). For climate change mitigation, the seamless harvesting of solar PV in combination with wind technology as a hybrid system is proving to be a key development. The hybrid solar–wind system will make economic sense in aiding growing economies with clean energy transformation to achieve development and climate goals.

GREEN POTENTIAL OF KEY RE TECHNOLOGIES

Renewable energy (RE) sources will play a dominant role in harnessing clean and affordable energy, especially in the tropical regions where solar energy is available for the most part of the year. When put together, solar and wind energy have a huge potential to meet the world’s requirement for an economical source of clean power.

The eco-benign clean power generation from eternal solar energy that doesn’t affect the ecology adversely, is increasingly supported by a consistent decline in generation costs and achievement of grid parity. The smart solar technology, with a high growth potential of 30%–40%, is emerging as an important media for energy security in the developing economies. Wind RE is an equally inexpensive alternative to fossil fuels. It is complimentary to solar energy and generates variable power. It is estimated that 13% of the world’s land area has wind speeds greater than 6.9 m/s at commercial wind-turbine heights. In 2017, global wind power capacity expanded by 10% to 539 GW. It is economically beneficial to include wind energy resource as part of the overall national energy mix.The energy demands are set to increase in developing countries. The ambitious target set by the Indian government is to achieve 100 GW of solar power and 60 GW of windpower installations by 2022.

Figure 1 shows the details of sector- wise global investments in clean energy based on Bloomberg New Energy Finance. The International Energy Agency expects renewable electricity generation to increase by more than one-third by 2022, and estimates that investment in clean energy will rise to almost $900 billion by 2035. The hybrid solar–wind combination has a promising future in challenging the intermittency, and more so in its commercialization using energy storage systems. Ultimately, solar and wind power, by virtue of their adoptability and affordability, would play a key role in clean power generation and help in overall decarbonizing, protecting nature by reducing carbon footprints, and reviving the global economy.

The blockchain technology marks an advancement in the distributed RE sector which can solve data management challenges while providing a smarter energy grid. Experts (at CNET, May 2018) are of the opinion that in the long term, this technology could democratize solar energy and help transform the very architecture of the grid itself (Picture 1).

DEVELOPMENT AND CLIMATE GOALS THROUGH HYBRID RENEWABLE

The dependence on the use of low- carbon technologies—mainly solar and wind—is increasing day by day due to their emission-free nature which helps tackle the problems caused by climate change. The dual benefits of generating economically viable green electricity—as an innovative solution for a seamless transition to sustainable development—are leading the world towards accelerated growth. Deployment of RE technologies together or in combination is also establishing energy independence in the developing countries, including India. At the recently held World Economic Forum in Davos, the Indian Prime Minister Shri Narendra Modi (Picture 2) reiterated at the opening plenary that “we are not only aware of our responsibilities towards climate change; we are willing to take lead in mitigating its effects” (World Economic Forum Plenary, 2018).

Shri Modi demonstrated the sustainability of India’s development process: “We have made major commitments and achievements in RE, and we are the fifth-largest producer of solar energy in the world.”

During the past two decades, commercially matured RE technologies have made great strides in the global energy mix across all sectors, namely, industrial, commercial, institutional, and residential. The main focus is on new technological innovations that combine solar infrastructure with that of wind, resulting in low investments that will lead to overall bankability of full-scale generation of clean power in the foreseeable future. For India, the main challenge remains to electrify each and every household in all its villages with quality power by 2022. However, the major part of the solution lies in establishing indigenously, the key drivers for an upward growth through state-of-the-art industrialization (Make- in-India approach) for a robust energy infrastructure and capacity building. India has committed to extend lines of credit worth nearly $1.4 billion to cover 27 projects in 15 countries during the founding conference of the International Solar Alliance (ISA) in March 2018, which was hosted jointly by the Hon’ble Prime Minister of India and French President Emmanuel Macron.

In a climate action summit held in Austria, UN Secretary General António Guterres asserted in his keynote address that none of the world’s challenges loom as large as climate change, and reiterated his belief that global warming poses an ‘existential threat’ to humanity (Climate Action World Summit, 2018). Climate change concerns across the globe have further propelled all nations to develop a detailed blueprint for clean and sustainable power for all. Grid stability, given the high penetration of clean energy, is critical for their economic growth, and thus has been given the highest importance. Solar- wind technologies are helping to create a situation where the share of electricity from both will play a central role in the future energy supply.

POLICY SUPPORT ON HYBRID SOLAR–WIND RE SYSTEMS

The MNRE has recently issued the final national solar–wind hybrid policy (MNRE: RE hybrid policy, 2018). The policy’s goal is to reach wind-solar hybrid capacity of 10 GW by 2022. The salient features of the hybrid RE policy are discussed ahead.

The main objective of the policy is to provide a framework for promotion of large grid-connected wind-solar PV hybrid systems for optimal and efficient utilization of transmission infrastructure and land, reducing the variability in renewable power generation and achieving better grid stability. The policy also aims to encourage new technologies, methods, and ways involving the combined operation of wind and solar PV plants.

Being variable in nature,wind and solar energy pose certain challenges to grid security and stability. Experts have suggested that in India both solar and wind resources are complementary to each other. A further superimposition of solar- and wind-resource maps shows that there are large areas where both wind and solar have high-to-moderate potential. The hybridization of these two technologies would help in:

1. Minimizing the variability
2. Optimally utilizing the infrastructure, including the land and transmission system
3. The existing wind farms have the scope to add solar PV capacity and, similarly, there may be wind potential in the vicinity of the existing solar PV plant.
4. An appropriate capacity of battery storage may also be added to the project to:

(a) reduce the variability of output power from the wind-solar hybrid plant; (b) providing higher energy output for a given capacity (bid/sanctioned capacity) at delivery point, by installing additional capacity of wind and solar power in a wind-solar hybrid plant; and (c) ensuring the availability of firm power for a particular period.

IMPLEMENTATION STRATEGY

The implementation of a wind-solar hybrid system will depend on different configurations and use of technologyas per the following details:

• Wind-Solar Hybrid: AC Integration In this configuration, the AC output of both the wind and solar systems is integrated either at LT side or at HT side. In the latter case, both systems use separate step-up transformers and the HT output of both is connected to a common AC busbar. Suitable control equipment are deployed for controlling the power output of the hybrid system.

• Wind–Solar Hybrid: DC Integration DC integration is possible in case of variable speed drive wind turbines using convertor-inverter. In this configuration, the DC output of both the wind and solar PV plants is connected to a common DC bus and a common invertor suitable for combined output. AC capacity is used to convert this DC power into AC power.

REGULATORY INTERVENTIONS

The central commission should lay down the guidelines for determining the generic tariff for wind–solar hybrid systems. Further, the commission should frame regulations for forecasting and scheduling for hybrid systems.

INCENTIVES

The government will encourage the development of wind–solar hybrid systems through various incentives. All fiscal and financial incentives available to wind and solar power projects may also be made available to hybrid projects. Low-cost financing for hybrid projects may be made available through the Indian Renewable Energy Development Agency (IREDA) and other financial institutions, including multilateral banks.

RESEARCH AND DEVELOPMENT

The government will support the technology development projects in the field of hybrid systems. Besides, support will be provided for the development of standards for hybrid systems. Detailed provisions for the existing and new wind– solar hybrid projects are also given in the policy document.

In order to remain energy-positive and to maximize the use of RE sources, the country will have to stay focussed on promoting grid-energy stability and efficiency. Recently, the Solar Energy Corporation of India or SECI (a government enterprise) invited bids for 2000 MW hybrid solar–wind projects (SECI: hybrid tender, 2018). This year, a private company installed a hybrid solar–wind project of 28 MW solar, close to its existing 50 MW wind plant in Raichur, Karnataka. It is expected that the savings in costs and increased efficiency with hybrid RE projects will in turn lead to lower tariffs and exponential growth in the power sector in India and other developing economies.

CONCLUSION

RE is at the centre of the transition to a zero-carbon-intensive energy portfolio. Renewable sources can produce electricity at close to, or even below, the cost of fossil fuel-based power stations and thus mitigate global warming. Today, India is amongst the fastest-growing solar markets (the fifth-largest in solar energy installations in the world). To meet the country’s exponentially growing power requirement, the Indian government is taking a series of initiatives for improving energy access with transition to renewables to achieve the country’s RE target of 175 GW, including 100 GW and 60 GW capacity for solar and wind power, by 2022. The main challenge for India remains to electrify each and every household in all its villages with quality power.

The existing growth opportunities along with high employment potential in the RE sector with the entire value- chain under its gamut is likely to benefit the diversified investors and funding agencies in bringing transformation in clean power generation while reducing the dependence on fossil fuels. The emission-free clean environment will be linked to the continued efforts of the ISA along with cooperation from other international agencies at the global level. The climate change challenge should be met by harvesting RE sources on a mass scale with cost-effectiveness and a time- bound programme and by simultaneously promoting skill development amongst the youth.

The green practices India follows to tackle energy challenges by harnessing renewables with scores of utility-scale projects are likely to provide holistic benefits to the country, its neighbours, and globally in terms of energy security, socio-economic development, job creation, and curbing GHG emissions.

Dr Om Prakash Nangia is Senior Consultant at Solar Energy and Director at New Era Solar Solutions Pvt. Ltd., New Delhi