Offshore And Onshore Wind Power: Clean And Renewable Energy Essay.

The History and Advancements of Wind Power Technology

In the category of clean energy, the wind power makes one of the most actively sort for energy resources and is developed on many countries around the world. The resource forms one of the oldest source of clean and renewable energy. In the early centuries the wind power was used in boat propulsion along River Nile, water pumping to large farms in China, and for draining lakes and marshy lands in Germany (Wind Energy Foundation, 2016). The increasing shortage and depletion of the fossil fuels (oil) around the world change the worldwide view of the energy picture, thus inspiring interests in alternative sources of energy: this therefore paved up way for the re-entry of wind turbine technology mainly for power generation.  Environmental and scientific studies in Europe resurfaced the immediate concern on the adverse effects in continued use of the fossil fuels to the environment, which indicated that the global climate would change if no alternative sources of clean energy were developed; therefore wind technology dramatically picked up, both in research and development in Europe. Today, wind power technology exists from small sized turbines for charging batteries to large onshore and offshore gigawatt sizes for electric supply to the national grids (Wind Energy Foundation, 2016).

Electricity is generated through the conversion of the wind’s kinetic energy (contained in air currents) into the rotation of wind turbines, as they flow past the turbine blades, which thus rotates a motor inside a generator to produce power. This power is then conveyed through cables down to the base of the tower which then combines with power from other windmills then collected at a local electricity distribution network (Marc , et al., 2010). The windmills are usually spread out in a common area (in a wind farm) for energy collection and also to reduce the adverse environmental impacts. Each windmill has a control computer system installed within to monitor the wind speeds then auto sets the blades to rotate at a safe speed. In cases of exceedingly high wind speeds, the computer control system ensures a complete automatic turbine shut down thus preventing the turbine from turning; this prevents cases of accidents (Genesis Energy, 2010).

Onshore wind technology has been on the lead in generating renewable energy in the United Kingdom with a 7TWh in 2010, an amount able to save 6 million tonnes of carbon dioxide which would have otherwise been released to the atmosphere. It is expected to generate about 30TWh by 2020 (American Geosciences Institute, 2011). It is true that the power sector is the whole problem to the global emission of greenhouse gases, but on the other hand it is the largest single contributor to these emissions – a share of about 40 percent of energy comes from carbon dioxide emission related sources. The dramatic progress of the developments in the wind and solar technologies in the past decades have pointed the world to the point for which the vision of having a clean sustainable energy in the near future, for the worldwide economy is well within reach, and has therefore become the explicit policy direction of many an increasing number of countries (Greenpeace International, 2014).

How Wind Power Generates Electricity

Figure 1: Offshore windmills (fixed-built and floating type) in Baltic Sea, Denmark (Daniel, 2013)

In contrast to the onshore technology, offshore wind power production involves constructing wind farms within large water bodies like the oceans or seas for wind energy harvesting used for electricity generation. There is available higher speeds of wind in the offshore compared to the wind speeds on land, thus there is a higher per unit installation so offshore wind power’s electricity generation is higher amount of power generated per unit capacity of wind turbines installed offshore than onshore. The offshore technology uses the fixed-bottom wind turbine for shallow waters as well as floating wind turbines for deeper-water areas, for which having a fixed type would prove uneconomical.  According to (Jonkman, et al., 2009), by 2017 18814 MW was the total worldwide offshore wind power capacity installed, with Northern European countries like the United Kingdom, Germany, Netherlands and Taiwan having the largest share of the total production. The Hornsea Wind Farm in the United Kingdom which is currently under construction will become the largest wind energy production farm when completed, giving a power capacity of about 1,200 MW (American Geosciences Institute, 2011). Taiwan’s greater Changhua’s offshore wind power station expects a capacity of 2400 MW installed. The general cost of constructing offshore wind power has always been historically higher than that required for onshore wind power generation, although this is currently on a decreasing trend in the recent years.

With the increased awareness on the effects of carbon emission to the environment, many states have invested in wind technology thus lowering the general cost required to set up a fully functional station. Many governments have provided incentives in this investments by giving fund incentives, technical trainings and organizing international fora for sustainable wind energy production (Wind Energy Foundation, 2016). Offshore windmills collects more energy as compared to onshore mills since the open water bodies allow for longer and larger mills to be constructed and also higher wind speeds in the seas (Daniel, 2013). Since the offshore technology utilizes the seas, large tracts of lands, which would otherwise been used (as in onshore type) are left for economic activities and there is also no blockage of wind flow to the mill by obstacles like buildings, that is prevalent in on-land wind technology.

Offshore wind turbines are commonly used by a number of countries chiefly, to harness the kinetic energy of strong and consistent winds that are found over the oceans. Roughly 50% of the total national population of the United Kingdom lives in coastal areas including counties directly on the shoreline or counties that drain to coastal watersheds. There are high costs and demand of energy thus often leading into a continued scramble on the limited on-land sources of energy, between the country’s rapidly growing industries and the bulging population (Office of Energy, 2009). Land-based renewable energy resources like onshore wind power production, geothermal power and hydroelectric power production stations, are often limited to the cities and thus cutting off the coastal areas. Therefore, the abundant offshore wind power that is usually efficient and clean, can potentially supply immense quantities of clean and renewable energy to the major populations in the United Kingdom coastal cities like Dornoch, Salcombe and Whitby, thus improving life and reducing the overbearing burden on the limited on land energy sources (Greenpeace International, 2014).

Onshore Wind Power Production

It is a common occurrence that there is a higher and uniform flow of wind speeds in the seas and oceans than on land, thereby increasing the speeds of wind by just only some few miles per hour will thus immensely produce a significant lager amount of wind electricity. This can be illustrated by considering a windmill in which the turbine at the site for which wind speeds of an average 16 mph act upon, would produce a 50 percent more electricity than a similar wind mill at a site whose blades are acted upon by winds of average 14 mph speeds. With this scenario and other innumerable benefits, many investors in the wind technology would therefore rather choose offshore wind power production to the onshore/on land wind power option ( Musial , et al., 2013). The United Kingdom’s department of energy through the National Renewable Energy Laboratory (NREL) provides the average wind speed data that has necessitated research and exploration of the offshore wind technology. With this technical data, the investors are able to determine the most efficient position and area to set up an offshore wind farm considering the wind speed and the depth of the shore.

As seen from the figure, wind speeds within the coast of Southern Atlantic and in the Gulf of Mexico are lower than the wind speeds off the Pacific Coast. On the other hand, the shallower waters in the Atlantic sea makes the current development of offshore wind farms more attractive and economical, owing to the fact that deep waters require large sums for investment. Hawaii has the highest estimated offshore power production potential, roughly accounting to 17% of the entire estimated United Kingdom’s offshore wind resource. The country aims at deploying a target to achieve a 20 percent the electric power entirely from wind energy resources (Mathew & Geeta , 2011). By May 2008, the Department of Energy gave an estimate that the 20 percent target can enable the country’s total offshore wind power to be 54 GW of installed electric capacity to the national grid. The department’s main ambition is to foster for energy independence, be an environmental steward and also to strengthen the economy of the states by availing cheaper clean renewable energy sources.

The United Kingdom’s department of energy in close association with the NREL has furthered out research works aiming at providing means of assessing the nation’s full potential in the indigenous resources on wind energy. The research has thus availed a national database of validated data that defining the significant and specific characteristics used to quantify the distribution and availability criteria of the essential resources. Of key importance are the annual average speed of the wind, depth of water within the shores, the distance from the shores to the minimum turbine locations and finally the state administrative areas. Musial and Butterfield, (2004) showed that accurate estimation of the full ability of the offshore wind power in the United Kingdom required that regions of potential wind power that are about 5 nautical miles off the shore be included in the overall estimation than just total exclusion ( Musial , et al., 2013).

Offshore Wind Power Production

The following factors are currently used by the energy department to estimate the states’ wind potential:

A yearly estimate of the average speeds of wind are an indication of the close relation to the possibly available energy within a particular location and are clearly distincted in category within the database by their approximate value at a height of 90 meters above the surface of the water body. These estimates are effectively done through advanced computer numerical models which are collected from ocean buoys, automated stations of the marine, lighthouses and the guard stations of the coast (Genesis Energy, 2010). Microwave imaging from the satellite showed a 10 meter wind speed over the ocean. In a general sense effective power harnessing from the wind can be effectively dove at a height of about 50 meters above the surface of the water.

This technology is used in the measurement of the depth of water in oceans, lakes of seas. In offshore wind technology, the depth of water greatly influences the technology specified for use to fully develop the offshore wind resource. The existing offshore wind turbine technology puts to use the monopoles or single-pole mechanism and gravity foundations within shallow water regions i.e. with depths of up to 30 m from the sea bed. Transition depths of about 30 meters to 60 meters require the use of tripods, which are truss-like towers and jackets while regions with deep waters having waters with depths higher than 60 meters uses floating structures rather than the fixed bottom foundations (although not widely used in U.S.). From the figure below, the eastern coast and the regions bordering the Gulf of Mexico have a notably extensive areas endowed with shallow water relative to the shore line and thus provide a good potential for offshore wind farms (Nina, 2014). On the West coast, there is a continued rapid dissension of the continental shelf into the category of the deep waters. There is also a notable increase in the water depth specifically away from shores surrounding Hawaii. In the regions bordering the Great Lakes, portions of Lake Ontario and Lake Erie there is a characteristic shallow waters while the other remaining lakes are categorized as primarily deep water lakes. There is a narrow band consisting of the shallow and transitional water near to the shore. The above data thus gives a clear shows that most of the coastal regions of the United Kingdom’s cities are potential areas useful for offshore wind power harvesting (USEIA, 2016).

Costs and Benefits of Offshore Wind Power vs Onshore

This factor is used to determine the wind power production project’s visibility from the shore i.e. the initial cost required for the development of a station by having a thorough consideration such as the length of underwater cable needed to connect the offshore wind project to land-based electricity distribution facilities (Wind Energy Foundation, 2016). The main goal of this consideration is to ensure there is a maximum energy production with minimal operating costs and capital costs. Most of the shores in the United Kingdom being shallow have shown that the distance from the shore is minimal (this results in lower electricity transmission losses) as compared to other countries thus minimizing the connection costs.

The offshore wind energy is a great source of clean and renewable energy. From the literature it is realized that the resource if correctly harvested can lower the carbon emission to the environment by almost 40% of the total annual carbon emissions. According to MacKay, (2008) the offshore wind farm is highly promoted by the U.K. government due to high productivity resulting from high and steady winds in the seas. This offshore method also saves on the limited physical space that could be taken by the onshore windmills (Mackay, 2008). The department of energy in the United States showed in their annual report that offshore wind energy does not contaminate the environment, since it involves no combustion of carbon emission products and the source is also inexhaustible.

Wind currents are always available and is naturally occurring hence there is no fear of the source being exhausted. The wind power is a chief source of clean power in regions of high wind speeds like Netherlands. Through the continued use of wind power, the demand for fossil fuels decreases greatly from the population and the industries thus limiting its use to only internal combustion engines requiring fossil fuels (Xiaojing, et al., 2012). This technology thus helps to prevent adverse climatic change in Europe. It is a leading technology at avoiding CO₂ emissions thus contributing to the continued commitment of the U.K. to cut out the poisonous gas emissions causing global warming and greenhouse gases (Marc , et al., 2010). A report by the University of Birmingham on the economies of Offshore Wind states that for every kilowatt-hour of wind power produced there results a reduced environmental pollution by a factor of twenty one as compared to the impact produced by oil; it is ten times less than the impact caused by nuclear energy that of nuclear energy and five times less than the gas energy effects.

The Importance of Wind Power in a Clean Energy Future

The clean wind energy can thus be diverted into running the main industries in the States and powering the nation’s population living within the coastal cities. The power scramble between domestic supply and industrial supplies is thus cut by 60% of the initial demand, the on land energy sources like the geothermal and hydroelectric power sources are thus relieved of the exploitation (Office of Energy, 2009). These surplus energy can then be channeled to the more demanding industrial sector to run the factories. The result is improved index on employment among the citizens, low production cost, highly improved living standards and thus reduced social related problems in the country. It is estimated that wind energy costs every average home a total of 1.3 Euros per month and also saves 160,000 euros for every United Kingdom industrial consumer on average annual rate. This makes the economy to greatly grow and open up wider international markets for the nation.

The available offshore wind energy has also improved the science and research works in the U.K. Most energy based researches have been funded by the surplus income generated as a result of the cut in the country’s power demand. The energy department has furthered out expensive exploration on better and new alternatives to cheap clean renewable sources of fuel. Notable is the increased research in the nuclear technology, The Nuclear Energy Institute in the United Kingdom has undertaken high levels of research into the most economical ways of generating power through nuclear technology and how to dispose the industrial refuse in a more environmentally friendly manner (American Geosciences Institute, 2011). This has thus supplied the country with nearly 20% of clean reliable and essential source of power, thus reducing the carbon emission to the atmosphere. There has also been a high investment in the clean solar power technology.

The plant includes utility-scale and local distribution scales, producing over 50GW of solar power installed capacity. This accounts for 1.37% of the total electricity in the United Kingdom. Most onshore wind farms negatively affect the human population due to the high noise levels associated with the rotating turbine blades and the generator noises. This makes them undesirable when located within the human habitat, the offshore technology therefore fills this niche since they are always located afar off human habitation. Most European governments have set up regulations covering the permitted noise levels produced from the windmills through the Acoustics legislation (USEIA, 2016).

Assessing the Potential of Wind Power in the United Kingdom

In the past decade, offshore wind power technology has witnessed remarkable increase in Europe and other countries like the USA. The Inter-governmental Panel on Climate Change presents a report showing that about 80 percent of the energy supplied would by 2050 come entirely from renewable sources. The increased improvement on the offshore wind technology has been witnessed besides higher station building costs and power transmission costs, these technological improvements have been witnessed in the United States of America, Europe and some countries in Africa.

According to Wind Energy Technologies Office (WETO), continued research inputs have enabled an increase in the average power plant productivity, i.e. power factor, from as low as 22 percent considering all the installed wind turbines as from 1998 to 35 percent average as at present and also an increase from the 2000 share of 30 percent ( Musial , et al., 2013). This has consequentially reduced the average costs of wind energy from the 1980’s fifty five cents per kilowatt-hour (kWh) to an average of below 3 cents per kilowatt-hour (kWh) in the United Kingdom as at present. For a sure continued industrial growth in the future there must be a continued evolution in the offshore wind industry by always endearing to build on the previous successes and limiting the inefficiencies thus improving the reliability of the technology, venturing into newer potential areas with increased capacity factors and reduced costs.

These include:

There are many examples of surface modifications that reduce resistance to flow and improve performance. The modification on the surface ensures that there are minimal viscosity drags on the turbine blades which would otherwise lower the rotation efficiency of the windmill hence increased wear of the turbine bearings and a lower energy extraction from the wind (Mackay, 2008). The recent invention by Sandia Labs, in which a fluid analysis software was developed predict optimal dimpling for any turbulent system for reduced flow drag. This modification can import fluid density and viscosity values, and also increase the heat transfer rate at surface for higher thermal efficiency. With this the wind turbines would thus be designed to sustain strong turbulent wind speeds with very minimal losses on the blade thus harvesting an almost constant power even with varied wind speeds.

The offshore wind farms face a major challenge in the building of the mill’s foundation within the water. With the strong tidal currents witnessed in oceans there is the development of large turbulent wakes in the rear of every windmill foundation which in the recent past have caused serious accidents in the seas. The foundations if not built strong enough tend to be destroy the wind farms leading to massive losses like Norway’s Verdal yard in February 2012 (OffshoreWINDbiz, 2012). The current design utilized a computer modelling analysis of the structural strength against the cost requirements for the foundation construction technique. This is applied only to the fixed-bottom type of windmills (Daniel, 2013).

This novel invention developed by NREL scientists is designed for desirable aerodynamic performance and minimal airfoil induced noise for small and large wind turbines (Simon & Geir, 2009). This design involves two airfoil families suitable for horizontal axis wind turbines (HAWTs) and a variety of other wind turbine designs. Each airfoil family provides a high maximum lift coefficient, exhibits docile stall, remains insensitive to roughness, and achieves a low profile drag.

Most turbine blades normally suffer from shock effects caused by the distributed wind forces thus failing faster than expected in cases where the design did not consider extreme wind forces. To contain this, the National Renewable Energy Laboratory in the United States developed a blade testing system using a motor as the prime mover to resonate the wind turbine blades by ensuring the oscillating blade system is tested at the root. This method eliminates the use of hydraulic pumps and actuators thus making it simple to use and less expensive. When compared to the traditional blade testing, the new method using base excitation has its frame mobile since it is self-supporting thus would require minimal anchor in the ground (Greenpeace International, 2014).

The energy department in conjunction to the United Kingdom have initiated scientific researches on improved materials that can be used to reduce the overall weight of the blades, have good stiffness characteristics and those that are highly resistant to corrosion. In particular offshore blades need to be very light, highly resistant to the corrosion, durable due to the extreme acidity in the oceans and seas. The use of thermoset composites have been encouraged due to their intrinsic properties of high resistance to fatigue and the high stiffness-to-weight ratios, thus showing tremendous performances. The composites are also easily manufactured into complicated shapes desirable for high performance characteristics. The blades are commonly made of fiber-reinforced epoxy material and also polyester due to high tensile and flexural strengths and easy manufacture method and low costs, respectively. Larger wind turbines producing up to 7.5 megawatts would thus require the use of more stiffer and light materials like carbon reinforced composites, this has therefore furthered research works in improved polymer materials.

The offshore wind technology, though clean, renewable and reliable source of energy has been faced with various barriers to its full advancement spanning from to technological know-how to high initial capital required for the investment. The method is also prone to risks if poor technologies are used (Office of Energy, 2009). The Energy Information Agency of United Kingdom said in 2010 that offshore wind technology proved to be the most expensive source of energy production due to the complicated nature of the principles required therein and thus it is usually considered suitable only for large scale deployments.

1. Cost:- the expected investment costs are approximately 1 Billion € only for the grid-connection for an installed capacity of 1 GW Offshore. Additionally the development of costs is still heavily volatile in that the availability of the ports with capacities for offshore windmill servicing and jack up inclusive of service-vessels required for the installation process are also a limiting cost factor. The cost constraint is also seen in the electricity transmission from the wind mills to the stations through the subsea cables, which are usually very expensive considering the insulation and delicacy required in the water bodies. The building of the power stations in the seas or oceans is also expensive thus limiting their use.
2. Technical uncertainty: - the skills required in the installation of an offshore windmill are naturally complex and thus require specialized training. This human resource is not always readily available in many countries. Most countries do not have universities offering high-level training on the technicalities around the offshore wind technology. This therefore hampers to a great deal the advancement and the popularity of the technology. The available training institutions are in few well advanced countries like the Netherlands, and United Kingdom which are also generally expensive(Daniel, 2013).
3. High operation and maintenance costs: - the maintenance costs required in the offshore industry is relatively high and thus rendering the technology a preserve of the developed countries. This is because of the equipment required for the maintenance like aircrafts and maintenance ships(Wang , et al., 2009). The materials required to set up a fully functional offshore wind turbine is also very expensive thus limiting their widespread adoption in the world.

Based on the above facts, it can be reasonably concluded that offshore wind technology is a clean source of renewable power to many countries that can be adopted by the states to cut by a great amount the use of carbon generating fuels like fossil fuels and biomass. The environment would thus be conserved and adverse environmental degradation effects like global warming would be highly reduced. The technology is obviously expensive and involves lots of carefully laid high-end technologies; therefore, the states opting for an investment in this filed would want their governments to actively support the project in terms of funding, training and spearheading the research workshops geared toward this filed. By this the total annual carbon (IV) oxide emitted to the atmosphere would thus be reduced.

The technology boosts the energy demand by most states around the world and thus improving their economies: countries like United Kingdom, United States, Netherlands, Taiwan have improved their economies by actively investing in the offshore wind power generation hence occupy higher economic ranks in the global market. Since many states are endowed with large coastal shores, the offshore wind technology can be well spread if only the right awareness and trainings can be done. More energy could be harvested from the investment and the world will have a greener environment. The high costs involved in the offshore power require the governments to support investors by giving tax incentives that would otherwise make the technology less expensive. Research activities needs be undertaken in the sector of improved materials that would enable large wind turbines be developed to produce large amounts of power. The continued depletion of the fossil fuel resources, their prices ever increase thus in the near future will shift the energy demand into offshore power sources.

References

Daniel, I., 2013. Drivers and Barriiers: The Implementation and Development of Offshore Wind Energy as a challenge for the Political and Private sector, Canada: University of Leipzig.

Department of Energy, 2009. Next-Generation Wind Technology. [Online] Available at: https://www.energy.gov/eere/next-generation-wind-technology
[Accessed 10 May 2018].

Genesis Energy, 2010. ELectrocity: How is Electricity Generated From Wind?. [Online] Available at: https://www.electrocity.co.nz/images/factsheets/Wind%20Energy.pdf
[Accessed 11 May 2018].

Greenpeace International, 2014. Global Wind Energy Outlook, New York: Global Wind Energy Council (GWEC).

Jonkman, J., Butterfield, S., Musial, W. & Scott, G., 2009. 5-MW Reference Wind Turbine for Offshore System Development, Colorado: National Renewable Energy Laboratory.

Mackay, D. J., 2008. SustainabLE Energy without the Hot Air, Cambridge: UTI.

Marc , S., Donna, H., Steve , H. & Walt, M., 2010. Assessment of Offshore Wind Energy Resources for the United Staes, Colorado: National Renewable Energy Laboratory - USA.

Mathew , S. & Geeta , S. P., 2011. Advances in Wind Energy Conversion Technology. Berlin: Springer Publishers.

Mehmet, B., Abdulkadir, Y. & Erdogan, S., 2011. Offshore wind power development in Europe and its comparison with onshore counterpart. Renewable and Sustainable Energy Reviews, 15(2), pp. 905-915.

Musial , W. D., Sheppard, R. E. & Dolan , D. N., 2013. Development of Offshore Wind Recommended Practice for U.S. Waters. Hawaii, National Renewable Energy Laboratory.

Nina, J., 2014. Environmental Impacts of Offshore Wind Power Production in the North Sea, 2014: WWF-World Wide Fund For Nature.

Office of Energy, E. a. R. e., 2009. Offshore Wind Technology Developnmment. [Online]
Available at: https://www.energy.gov/eere/wind/offshore-wind-technology-development-projects
[Accessed 10 May 2018].

OffshoreWINDbiz, 2012. Norwau: Knaever Completes Investigation Following Serious Mill Accident. [Online]
Available at: https://www.offshorewind.biz/2012/03/13/norway-kvaerner-completes-investigation-following-serious-mill-accident/
[Accessed 11 May 2018].

Simon, P. & Geir, M., 2009. Status, plans and technologies for offshore wind turbines in Europe and North America. Journal of Renewable Energy, 43(3), pp. 646-654.

USEIA, 2016. International Energy Outlook, Washington D.C.: U.S. Energy Information.

Wang , Z., Jiang, C. & Ai, Q. W. C., 2009. The key technology of offshore wind farm and its new development in China. Renewable and Sustainable Energy Reviews, 13(1), pp. 216-222.

Wind Energy Foundation, 2016. History of Wind Energy. [Online]
Available at: https://windenergyfoundation.org/about-wind-energy/history/
[Accessed 11 May 2018].

Xiaojing, S., Diangui, H. & Guoqing, W., 2012. The Current State of Offshore Wind Energy Technology Development. International Journal on World Energy Sources, 41(1), pp. 298-312.