When thinking about renewable electricity for your home, two options spring to mind; photovoltaic panels and small wind turbines. But which one should you choose? The government has introduced a feed-in-tariff that pays a subsidized amount for the electricity they produce and the amount paid for small wind turbines is similar to that paid for small PV systems (34p/kWh compared to 41p/kWh).

The key criteria to deciding which technology will be the most profitable is the cost of producing a unit of energy from each one. For this you need to factor in the up front costs such as equipment and installation, and then look at how much energy they will produce once out there over an average year. Without going too heavily into numbers my argument is that in some instances, micro-wind turbines will have a lower cost of energy than solar panels, but for the majority of cases solar panels will be better and this can be explained by some basic science.

Without a doubt, on a large scale, wind energy is cheaper than solar. The cost of energy from large-scale wind farms is somewhere around 10p/kWh whereas the cost of energy from large-scale solar is three to four times greater at present. Big wind turbines are now very well designed products and many years of industry development means that the costs have fallen dramatically and continue to do so. Big solar farms are also rapidly reducing in cost and make a lot of sense in some locations, particularly in the many regions where wind farms are not suitable, but for now they do not compete.

On the small scale however, the economics are drastically different. As the size of a solar installation decreases, the performance falls linearly with the amount of area used, and therefore the cost of energy does not change so dramatically. In contrast, as wind turbines get smaller their performance gets disproportionately worse. This is for two mains reasons:

The first reason is that as the turbine blade length gets shorter, the ‘swept-area’ decreases quadratically. This means that if you decrease the length of a blade from 80 meters to 40 meters, the area covered by the blade decreases from 20 thousand square meters to just 5 thousand. The ‘swept-area’ determines how much wind energy the turbine can use. So when you decrease the blade length you still need all the expensive moving parts like the generator, but you get disproportionally less energy – for one big wind turbine you would need thousands of smaller ones to cover the same area. The second reason is that where you use micro-wind turbines the wind speed is generally slower. This is because most of us live in built up areas where there are other buildings nearby. These buildings disrupt the wind, making it irregular and slow. Wind speed is crucial to the effectiveness of a wind turbine, again because the energy contained in the wind is disproportional to its speed. If the wind speed drops by a factor of 2, the energy produced by a wind turbine decreases by a factor of 4. Comparing most built up areas, the average wind speed is much lower than half the wind speed found high-up in open spaces where you find most wind farms.

These two factors combine to mean that for most homeowners solar panels are the most sensible and safest option. Of course, if you live near an open space and get a lot of wind then a micro-wind turbine could be a great investment. However, if you do live near a windy open space, I would suggest trying to build as big a wind turbine as possible, as their cost effectiveness increases dramatically with size.

In a bid to increase profitability among its offshore wind farms, China has introduced a feed-in tariff system designed to make the generation of electricity via wind farms economically viable. China has recently been a leading advocate of the tariff system as the Beijing government seeks to diversify both the economy and the means of energy generation. With the New York Times last week announcing that green power is taking root in China, the move to encourage the take up of wind power generation comes as no surprise as the Asian government is supporting all kinds of renewable energy, especially solar and wind.

The Chinese wind feed-in tariff system will inevitably attract investments in the offshore wind generation industry there with the hope that it will enable the clean, wind energy to compete with that generated via coal fired plants. The guaranteed premium rate which will be offered to wind generators will be met by the existing grid operators with the additional cost being spread over all electricity consumers. The idea is that bigger, more profitable wind plants will receive a more generous tariff rate in order to help them catch up with the bigger wind farms.

The tariff payments are set at around 0.51 Yuan the equivalent of £0.05 per unit of electricity fed in to the grid, depending on the size of the wind farm. Compared with the rate paid for coal fired electricity (0.34 Yuan) the wind farms will e set to receive a generous payment. The announcement by the National Development and Reform Commission (NDRC) stated that the scheme will,

“change current inconsistent pricing, foster clear expectations and facilitate investments in the sector”.

The previous system which operated regarding wind power electricity purchasing involved public bidding using low-rate tariffs which did not enable most wind farms to gain grid connectivity, a hindrance which meant that at least 20 per cent of China’s wind power producers were unprofitable. With the feed-in tariff system generally regarded as by far the most effective means of generating capital in green energy, China will be set to succeed in its bid to diversify its economy and become a major player in the world of green energy production.

The announcement last week that the largest onshore wind farm in Europe is to be expanded is set to offer a massive boost to renewables in the UK. The announcement by the Scottish first minister Alex Salmond will see the construction of a further 36 wind turbines on the site. The permission to extend the East Renfrewshire site by the government will be seen as a step towards realizing some of the rhetoric spoken this week in regards to a ‘green new deal’ in Britain.

Gordon Brown’s announcement at the beginning of this year about the introduction of a green new deal, was a reference to the reforms made by the Roosevelt administration in the face of the 1930s depression which gripped the world. Many were encouraged by the language of the announcement, believing it to be a real indication of a move towards a green economy. Certainly, the extension of the Eaglesham Moor wind farm site will go some way to contributing to the low-carbon economy espoused by politicians in recent months.

In real terms, it is likely that the wind farm expansion will lead to the creation of around 300 jobs and will make the site the first over 300MW in Europe with a total capacity of 462MW, enough to power up to 250,000 homes. As the UK government seeks to meet its climate change targets of cutting carbon emissions 80% by 2050, the Whitelee wind farm will provide evidence that there is at least some tangible work being done to both establish a green economy and meet its targets.

Speaking about the expansion of the wind farm expansion, Alex Salmon commented,

“Whitelee in its current form is already flying the flag for onshore wind power in Europe. The planned extension, which I am delighted to announce today, will enable the wind farm to harness its comparative and competitive advantage in wind generated energy within Europe.

He went on to add, “It has the infrastructure, the expertise and the capacity to continue to develop in the future.”

REpower has successfully installed three of its six megawatt (MW) turbines near the German-Danish border, bringing the massive new turbines closer to their final destination: offshore wind farms.

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