Renewables

The following article is the result of an interview with François and Benoît Henriet of the Belgian wind energy development company Greenwind. The article is published as an eBook so you can scroll the different pages using the titles below. The full article is also available as a PDF for download.

---

 

The wind energy industry is booming worldwide, favoured by ambitious targets for renewable energy, various subsidy mechanisms, and rising prices for fossil fuels. This does not mean however that wind companies have struck gold. A wind development project is a complex affair with many barriers and one requiring favourable climatic and geographical conditions that are available in only relatively few countries in Europe. Leonardo ENERGY talked with François and Benoît Henriet of the Belgian wind development company GreenWind about the difficulties in finding appropriate wind park sites and about the future potential for wind energy in Europe.

 

 

 

By M C Benhabib et al

In the next decade the amount of decentralized generators will significantly increase in the distribution networks. Among the sustainable energy sources, the research on photovoltaic generators has received much attention, especially the study of residential photovoltaic (PV) systems, which has potential of becoming a significant market. Measurements in a bungalow park in the Netherland with a high penetration of PV have shown a lot of harmonic distortions at the point of coupling. There harmonics are concerning resonances and the interaction of current harmonics generated by the inverters and the voltage harmonics coming from the grid.

This paper, will study the influence of the current harmonics generated by photovoltaic systems connected to the low voltage network and the interaction with other non-linear loads and the network voltage. Basis for this simulation is a neighborhood in the Netherlands with around 96 houses. Simulations will show the effect of these harmonic currents generated by big amount of photovoltaic systems and common electronic loads and the interaction between them.

By E Diaz-Dorado et al

The study of energy losses in any electric installation is closely related to energy efficiency. Its calculation depends on the number and the quality of the available electrical measurements. Typically, every wind park has electrical measurements in all its wind turbines and its HV point of connection. However, it is difficult to calculate in an easy way these losses due to problems like redundancy, inaccuracy, lack of data, etc.

A state estimation (SE) method will be proposed in this article, in order to calculate the power losses. By means of available measurements (power, voltage, current...) and parameters of the network (cables, transformers...), the losses taking place in each element can be obtained. SE also allows detecting errors in measurement and calculating the wind park state when certain measurement equipments are unavailable. Wind speed measurements are used to get pseudo-measurement if necessary and to filter errors.

Finally, an economic study will be done taking into account the different ways of selling wind energy in the Spanish network. Consequently, the economic importance of losses will be evaluated too.

The location of this project is The Sotavento Wind Park, Serra da Loba, Spain. The results shown throughout this article have been applied there with the aim of analysing its energy efficiency.

In countries like Germany, Denmark, or the Netherlands, wind power is already so widespread that few onshore sites are left on which new units can be built. Two main paths are being followed to further increase the electrical power generated by wind: building offshore wind parks, and replacing existing wind turbines with new and larger types (3 to 5 MW). The older, replaced types are appearing on the second hand market and will allow other (developing) countries to start using wind power at lower costs.

The second booming development in wind energy technology particularly affects countries like Denmark and Germany that are running short of productive sites. In these countries, it is more efficient for investors to replace smaller and mid-sized turbines on highly productive sites with newer and larger turbines, rather than just building the new turbines on less productive sites. This process is known as “Repowering”.

The successful implementation of wind energy in Europe during the past decade and the continued economical support offered in national legislation have led to a developing market for secondhand wind turbines. Repowering of plants after five to 15 years of operation releases a large number of turbines into the market. For developing countries, this is an opportunity to gain experience in working with renewable energy sources, to establish their own wind energy industries and to profit from technology transfer with low capital expenditure.

This document describes the status quo regarding wind power for several regions and countries in the world, as at the end of 2007, It describes the principle of repowering (as performed in Germany and Denmark) and covers the developing market for used wind turbines.

Register to obtain a free electronic copy of this report

Due to economic social cohesion, the European Union is promoting to improve the production of electrical energy from renewable energy sources (see briefing presentation about EU renewables Directive). Sea waves have associated a form of renewable energy which can be captured by using a hydro mechanical device that in turn drives an electrical generator to produce electrical energy.

After a brief description of wave formation and quantifying the power across each meter of wave front associated to the wave, the paper describes several devices used presently to extract mechanical energy from the waves and their advantages and disadvantages are presented as conclusions. In particular, the modern Pelamis system is described in some detail. Wave energy market is also discussed.

See also a video of Pelamis device in service :

 

Up to 40.8% of the overall electricity demand is supplied by wind power at some moments of the day in the Spanish electricity system. This record constitutes a real challenge for transmission system operators (TSOs).

In more general terms, renewable energy penetration strongly depends on the ability of TSO to evolve towards a new way of operating the system: dedicated predictability for renewable generation, voltage dip management and managing the power balance.

The big issue for the coming years (especially taking into account the targets set by the EU Directive on the use of energy from renewable sources) is balancing the transmission system in the presence of high renewable power penetration. This not only requires to redesign grid codes, but also a deep revision of power reserve policy. Along with renewable sources growth, a market for upgraded reserves is becoming necessary.

This paper shows some good practices from the Spanish TSO, REE, leading to better integration of renewable generation: commissioning a dedicated centre for renewable energy management, grid code evolution, development of specific applications to maximize renewable generation and provide production limits to each renewable energy plant, voltage control and congestion management.

Based on a Discussion Webinar, Friday 7 March 2008

Without significant feed-in tariffs or other types of government support, photovoltaic energy is not yet competitive with fossil fuel or nuclear power generation. But the technology is on a learning curve and the so called “grid parity” – competitiveness with conventional electricity generation is approaching.

But are we on the right learning curve? How far away from grid parity are we today and how much does it depend on geography or on other specific conditions? And which actions or conditions could speed up the learning path?

Is grid parity a useful parameter, or rather a non-issue? What does “grid parity” really mean? Is it parity with wholesale price or with retail price, with or without taxes?

These and other questions were addressed on a Discussion Webinar on 7 March 2008. The following are a few of the major points arising from that discussion.

Below is the presentation from the March 7th webinar on this subject

A new series of FAQs on wind energy.

 

Other FAQ series

Test your knowledge of Wind Energy Systems in just a few minutes. If you want to go deeper, or gain a better understanding of the right answers, you can find additional interactive resources on the Wind Energy microsite. (“How To” Manual, Frequently Asked Questions...)

If you take the AC output of your Inverter and run it to the mains coming from your utility power meter, any excess power you generate will feed back into the utility grid and drive your power meter backwards. This is called Net Metering. Effectively, you will be paid the going retail price for your electricity up to the amount of energy you use per billing period. Any excess energy you generate will be credited at a lower rate, or perhaps not at all.

In many countries, the whole amount of wind electricity generated is purchased by the utility company at a rate higher than the tariff applied for consumed electricity. In this case, a dedicated metering exists for wind generation, plus a second metering for domestic consumption. Each applies different tariffs, so in this case, not only the excess electricity is remunerated, but the total amount of wind production.

Electrical utilities in many countries give retail credit to customers who feed excess wind electricity back into the power grid. Known as "net metering," this utility policy is implemented by letting your electric meter spin backwards when you feed excess electricity into the grid. In many countries, the whole amount of wind electricity generated is purchased by the utility company at a rate higher than the tariff applied for consumed electricity. In this case, a dedicated metering exists for wind generation, plus a second metering for domestic consumption. Each applies different tariffs. So in this case, not only the excess electricity is remunerated, but so too is the total amount of wind production.

No. Batteries are only essential if you want 'back-up' power in the case of a utility outage. Otherwise, your grid connected Wind Energy system will send any excess generated electricity back to the utility, using the utility grid (rather than batteries) as the storage medium.

A grid connected Wind Energy system can continue to provide electricity to your home during an outage if it has a inverter and batteries.

No. The cost of Wind Energy technology has dropped dramatically in last years and, thanks to government incentives or subsidies, a Wind Energy system may be your most cost-effective power solution.

Grid connected means that your system is connected to the utility lines or the quot;grid". A grid connected Wind Energy system is designed to meet all, or a portion of your daily energy needs. This connection enables you to obtain the balance of your electricity from your local utility. It also allows you to send excess solar electricity back to your power company for use later.

Wind turbines, like all electrical equipment, produce electromagnetic radiation, which can interfere with broadcast communications. This interference can be overcome through the installation of deflectors or repeaters.

Photovoltaic systems allow you to lock in your electric rates at today's prices. With fossil fuels likely to become more expensive in the future, purchasing a Wind Energy system today is a smart economic move. In some countries, there is the possibility of having feed in tariffs or incentives to invest. Wind Energy systems also offer greater self-sufficiency, reduce dependence on imported oil, and are far better for the environment than power from conventional power plants.

Wind farming is popular with farmers, because their land can continue to be used for growing crops or grazing livestock. Sheep, cows and horses are not disturbed by wind turbines.