The promising impact of renewables

Constant need for electricity drives rapid growth of renewables

By Jewel Thomas

The wide-ranging environmental, economic and employment benefits of the rapidly expanding RE (renewable energy) sector are multiple and go beyond solely electricity generation. “New” RE sources, i.e. wind, solar, marine energy and biomass are now the fastest-growing power source on a percentage basis with hydropower representing the biggest share. This rapid growth is driven by a constant need for electricity and environmental concerns to also reduce the use of fossil fuels in power generation.

Horizontal axis tidal turbine (Siemens press photo)
Horizontal axis tidal turbine (Siemens press photo)

Economic benefits and challenges

According to a BNEF (Bloomberg New Energy Finance) April 2014 report, investments for REs could range between USD 470 billion (USD 6 100 billion cumulative) and USD 880 billion (USD 9 300 billion cumulative) by 2030. Although these figures should be taken with caution, they highlight a growing market and societal interest. Tax-breaks and subsidies to bring the price of RE-generated electricity to that of other sources, causes costs to decline equally rapidly, making renewables increasingly competitive. However some utilities find their conventional power plants, which are generally still needed for backup, become unprofitable. As a result, some countries are considering or cutting financial incentives for RE installations. Nevertheless, employment opportunities should continue to grow in manufacturing, equipment distribution, site preparation, installation and also benefit industry suppliers. With production gradually moving to developing countries, prospects in REs should be promising there too especially in the MRO (maintenance, repair and operations/overhaul) sector.

The extensive standardization work done by several IEC TCs (Technical Committees) and SCs (Subcommittees) is crucial in the development of the RE sector and its associated technologies. A summary of recent developments follows.

Marine energy

Marine energy is emerging as a huge source of RE but depends on disparate kinds of energies, which require different technologies for their full exploitation. Due to various challenges, investment in this sector has been relatively modest so far.

IEC TC 114: Marine energy – Wave, tidal and other water current converters, is preparing International Standards to help reduce the technical and financial risks associated with new technologies in this sector and enable a quicker adoption of marine energy conversion. The TC also liaises with IEC TC 88: Wind turbines, on marine energy projects that share some technical issues with offshore wind farms on common elements, such as mooring and floating installations.

Three TS (Technical Specifications) have been published and work on a Guideline for design assessment of OTEC (Ocean Thermal Energy Conversion) is in preparation.

Steam turbines: a hot global market

Introduced in the late 19th century, steam turbines, which use heat derived from burning fossil fuels, from nuclear reactors, biomass and other renewable sources to drive generators, have been in high demand ever since for electricity generation, marine propulsion and in industry. They are responsible for producing some 80% of the world's electricity. The technology has evolved considerably and the increased flexibility of steam turbines enables them to be used for a wide range of applications.

IEC TC 5: Steam turbines, prepares International Standards that have contributed to the expansion of the sector. They concern specifications, as well as acceptance tests related to the accuracy of various types and sizes of turbines and of speed control systems.

Thermal solar power

CSP (Concentrating solar thermal power) is attracting the interest of utility companies keen to expand their renewable portfolios, but also of original equipment manufacturers. One reason is the many common - but cleaner - traits with fossil fuels.

Different CSP technologies can be applied to collect and concentrate sunlight, turning it in to medium to high temperature heat. It can then be used to generate electricity in a conventional way using a steam turbine or a Stirling engine, or used in other applications, such as supplying process heat. Advances in technology– including the vital thermal storage capacity that enables solar variability to be decoupled from a plant’s output – are contributing to a series of major new commissioned projects in various parts of the world.

Thermal energy is relatively easy to store unlike electrical energy. New developments also include the capacity to generate electricity in the night. The main types of commercial CSP technologies in operation today are linear systems like Fresnel lensing, parabolic trough types, point concentrating systems and the more common central or tower receiver systems. Commercial storage technologies in use are steam storage in pressurised vessels and molten salt storage using insulated tanks.

Reducing energy costs and improving thermal storage systems represent the biggest challenges. The work of IEC TC 117: Solar thermal electric plants, will be central especially regarding terminology, performance testing, modelling, environmental, and safety requirements.

Geothermal energy

Geothermal energy, heat from the Earth best known and most visible in natural form in geysers, is an abundant form of renewable energy present everywhere. Although geothermal energy application in power generation is relatively recent, its exploitation is expanding rapidly throughout the world. It is proving particularly attractive for countries without easy or affordable access to other forms of energy. Its potential is being increasingly also harnessed for many applications such as heating buildings to produce electricity in power plants, cooling, and in CHP (combined heat and power) cogeneration.

Several countries in Africa and the South East Pacific region are making significant progress in the development of their first geothermal power plant, with plans to meet national energy needs and electricity export to other countries.

Geothermal heat pump systems are very efficient and outperform other forms of heating and cooling that rely on fossil fuels or electricity. A new promising technology is EGS (Enhanced Geothermal Systems), which employs techniques developed for enhanced oil and gas recovery (also known as fracking). However, constraints on EGS include economic, technical and environmental factors such as potential landslides.

Standardization work is essential to the proper operation and development of geothermal energy for example with IEC SC 61D: Appliances for air-conditioning for household and similar purposes, which prepares International Standards for heat pumps. With steam turbines being central to electricity generation from geothermal sources the work of IEC TC 2: Rotating machinery will also be key.

Horizontal axis tidal turbine (Siemens press photo) Horizontal axis tidal turbine (Siemens press photo)
Stirling dish for CSP plant Stirling dish for CSP plant
Horizontal axis tidal turbine (Siemens press photo) Geothermal energy plant at The Geysers near Santa Rosa, California, USA (Photo: NREL)