The Alternative Energy blog – green renewable alternative energy

Wind energy is both green and fun, so the idea of building one’s own wind turbine is a good one. The following will give you an idea of what is involved.

Wind energy on a large scale is now competitive with other sources of electricity on a commercial scale. However, small domestic-sized wind turbines have not yet reached this point. The wind is free, but small wind turbines are expensive in relation to what they produce, and cannot realistically compete with mains electricity. Building your own machine saves some of the cost, but please do not underestimate the difficulty of the task. If it were easy to save money by using small wind turbines, then they would be a major feature of the landscape by now.

Most residential locations are not suitable for windpower as trees and buildings break the force of the wind, and create turbulent gusts which can be very destructive. Open hilltop sites or coastal situations with unobstructed views may be suitable for siting a wind turbine. A very tall tower is helpful, but these are not always appreciated by your neighbours.

What size of wind turbine do I need?

Wind turbines work with thin air, so they need to be large in relation to the power they produce. To power a modern home on a good site, the blades would need to span about 5 metres from tip to tip. This is known as the rotor diameter. With careful conservation of energy a smaller machine may suffice. A rotor diameter of 2 metres might yield about 500 kWh of electricity per year, compared with an average annual household consumption of roughly 4,500 kWh.

What sort of generator should I use?

Most small wind turbines are used for charging batteries, to provide a reliable stand-alone power source where grid power is not available. The obvious choice of generator for self-build is the car alternator. However this has major drawbacks. It must be driven at a high shaft speed (over 2000 rpm) to give full output, so you will need to gear it up or modify it in some way to drive it with rotor blades, which typically only manage a few hundred rpm. This reduces the efficiency. In low windspeeds there is very little power available in the wind, and you need a highly efficient generator to capture it. Most, if not all of the power in light winds will be used up energising the magnetic field in the alternator, so the results are disappointing. Nearly all small commercial wind turbines use purpose-built permanent magnet generators for this reason. The DIY enthusiast can make one too, but this is not simple to do. Or you can reuse a permanent magnet motor as a generator. The generator is the key to success or failure of the project, and by far the hardest part to get right.

Can I make my own blades?

The good news is that yes, many beginners have made very useful wind turbine blades, often carved from wood. Or there are sources where you can buy them ready made. If you plan on making your own, it is well worth doing some research and finding out all you can about it in advance. Not only will this save you from ‘reinventing the wheel’ but it will also be safer. Safety is an important issue even with the smallest wind turbines. Never underestimate the destructive power of a runaway windmill rotor in a high wind. Make sure that you have built-in protection against all eventualities. Control systems are as important as any other part of the wind turbine.

Its not easy building your own wind turbine but with skill and dedication it can be very satisfying.

In just over a decade China is expected to become  the world’s largest producer and consumer of alternative energy, according to experts. 

China’s installed wind capacity has doubled in each of the past four years.

In addition, in just a little over four years, a mix of government and foreign investment has transformed the Chinesport city of Tianjin city into the global manufacturing hub of the world’s wind power industry.

The country also has one third of the global solar panel market.

Many experts now seem reasonably optimistic that China could meet its ambitious renewable energy plans to derive at least 15 percent of all energy from renewable sources by 2020. The country also is striving to reduce energy intensity per unit of GDP by 20 percent over a five-year period.

All this in a country  that has some of the worlds most polluted air and water.

Ironically the country is poised to be at once the world’s leader in alternative energy — and its leading emitter of C02. 

Alternative energy as a percentage of the total energy mix is increasing, but it will complement — not replace — growth in coal power. In fact, in a decade coal is expected to supply about 70 percent of China’s energy. Because of the sheer scale, diversity, and complexity of China, it is possible for the country to take some great green leaps forward while at the same time having its rivers remain black and its air quality a health hazard.

Taiwan is to invest $1.4 billion in the island’s domestic renewable energy sector, its government said today, in a move it says will help the sector grow nearly eight-fold by 2015.

“The green energy sector can turn Taiwan into a major power in energy technology and production, as well as provide the creation of green jobs,” Taiwan’s Premier Liu Chao-shiuan said in a statement.

The statement did not say over what period the investment would be made.

Householders convinced that the UK does not have enough sunshine to effectively use solar panels are ‘wrong’, according to a domestic solar panel advisor.

The UK energy advisor Heat my Home has explained that the panels operate on solar radiation not sun rays and the UK gets enough of this to run solar.

Stuart Lovatt of Heat my Home said: “One unique selling point with solar is the longevity. A good quality system will easily last 30 years, so the long-term benefits of solar are obvious.

“How many things today can you buy with such a long lifespan, but solar does, and this makes it a perfect investment if you are thinking long-term such as retirement.”

Germany is the biggest installer of solar panels in Europe and shares a similar climate to that in the UK, both of which receive around 60 per cent of the solar radiation levels the equator does.

Investments  in green energy are set to rise says Ethical Corporation magazine.

It argues that the  impact of climate change will alter the shape of the global economy over the coming years resulting in an expanding  environmental technologies sector that will  provide both attractive and long term investment opportunities for global investors. 

A decade ago very few environmental technology investments were available for investors, other than those from a small number of pioneers specialising in this area. Today it’s a very different story. Institutional and retail investors have access to a wide range of environmental and climate change investment options, with an estimated $50bn invested in environmental market funds globally.

Experst says it will not only the renewable energy sector that will benefit from the changes required to deliver a low carbon economy.  Companies emerging from sectors such as energy efficiency, water infrastructure and pollution and waste control also have important contributions to make in addressing not only climate change, but the interrelated wider environmental threats facing society.

Fascinating article in Scientific American reports how mirrors are harnessing the sun to generate electricity in California.

Californian Power Tower

In southern California’s Antelope Valley, 24,000 silver-bright mirrors have been positioned to reflect light on two 50-meter-tall towers. And at 11:08 A.M. local time Wednesday, this concentrated light heated steam in those towers to turn a turbine— the first “power towers” in the U.S. to convert the sun’s heat into electricity for commercial use.

Dubbed Sierra SunTower, the power plant can produce five megawatts, enough to power roughly 4,000 local homes at full capacity—and provide the modular blueprint for larger plants in California and New Mexico, according to eSolar the Pasadena start-up behind the power plant.

“We call this a commercial demonstration,” says eSolar senior vice president of engineering Craig Tyner. “A 46-megawatt commercial design will incorporate 16 of these towers, two of which we have at Sierra” as well as more than 200,000 mirrors capable of generating at least 90 gigawatt-hours of electricity per year.

Regardless of whether you choose clunky roof panels or integrated tiles, the basic principle of solar panels is the same.

Solar panels are made up of a series of photovoltaic cells, consisting of layers of a semi-conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers causing electricity to flow. The more intense the light, the more electricity you generate – but remember, it’s light and not heat that matters, so you’re not totally at the mercy of the weather.

A two-way meter clocks up how much power you import from the national grid, but literally runs backwards (making you a profit) when your home is doing the generating. Or you can store the electricity you generate during the day in batteries for use during the night.

UK supermarket chain Tesco has announced that it is sending its waste meat to be converted into renewable energy for British homes.

The retailer has proudly revealed that it is recycling all of its meat waste to heat and electricity, stating that the 5,000 tonnes of out-of-date meat that it sends to biomass plants will generate 2,500 Mega Watt Hours of renewable energy each year – enough to power more than 600 homes for a year.

But the innovative scheme has come under attack from vegetarians.The Vegetarians International Voice for Animals (Viva) has branded the scheme as “macabre”, claiming that many consumers would be “horrified” to discover that their power was created from meat.

Viva campaign manager Justin Kerswell said that the supermarket would not need to recycle the waste meat if they did not over-order in the first place and described the scheme as a “sickening plaster solution”.

Tesco has defended the scheme, pointing out that meat is only a small proportion of the waste that is being turned into energy. The retailer is now diverting 100% of the waste produced by its entire UK business away from landfill in a bid to improve its environmental performance.

Tesco executive director Lucy Neville-Rolfe said: “Climate change is the biggest challenge facing us today and businesses such as Tesco have a responsibility to provide leadership.”

A new exciting technology to harness the power of waves and turn it into green energy was announced this week.

A giant machine called’ Oyster’ is being installed on the seabed of the Atlantic Ocan off Scotland’s Orkney Islands.

This autumn Oyster it will undergo demonstration trials to prove whether its innovative technology could lead to a commercial source of renewable energy for use in seashores around the world.

In contrast to many other wave power devices, Oyster uses hydraulic technology to transfer wave power to shore, where it is then converted into electricity.

“‘Oyster’ technology is highly innovative because it relies on simplicity. “says Dr Ronan Doherty, Chief Technical Officer of Aquamarine Power the Edinburgh based company which has developed the first ‘Oyster’. “Its offshore component -a highly reliable flap with minimal submerged moving parts – is the key to its success when operating in seas vulnerable to bad weather where maintenance can be very difficult. There is no underwater generator, power electronics or gearbox underwater to go wrong. All the complex power generation equipment remains easily accessible onshore’.

Although at an early stage of development, the Oyster concept could have significant potential for use in many locations around the world. Dr Doherty explains: ‘Our computer modelling of coastlines suitable for this technology shows that Spain, Portugal, Ireland and the UK are ideal candidates in Europe. But globally there is huge scope in areas like the North West coast of the USA and coastlines off South Africa, Australia and Chile. We estimate that the potential size of the market could be in excess of £50 billion’.
Based on figures from the Carbon Trust, each Oyster’s annual carbon saving could be as much as 500 tonnes.

Venture capitalists in the USA are heading back into the alternative energy sector. Investments in the sector have increaesed by 73 percent in the last 3 months.

A report issued today by Ernst & Young LLP says venture capital investment in the clean-technology sector totaled about $572 million from April to June.
That’s still far less than the money invested during the second quarter of 2008, a big year for alternative energy, but suggests that the worst may be over for solar, wind geothermal and other cleantech businesses.