You are here:

Welcome to our blog

This is to prevent automatic submissions.

Back to postings list

Posted by Kim Winter, Tuesday 30th October, 2018

Green energy today

offshore wind turbines

 Ann Lee reports on the third annual Brixton Windmill lecture, held in Lambeth Town Hall on Wednesday 26 September. 

Two expert speakers explored the history of renewable energy and its potential for fulfilling our energy needs. An audience of around 50 people were treated to a dazzling panorama of clean energy developments to set against the prevailing gloom about carbon emissions and climate change.

Repowering London

Agamemnon Otero, CEO of Repowering London, gave a lively presentation on the innovative work his organisation is doing to support community initiatives for social and environmental benefits - including solar energy projects in Brixton, Hackney and Vauxhall, and renewable energy generation in schools in Norwood and North Kensington. A new scheme called Energy Garden combines community building, energy and gardening projects. Funds are also allocated to help tackle fuel poverty through education in energy efficiency.

The model for Repowering London's solar energy projects is to work closely with local community groups and professional installers, while offering internship opportunities to young trainees and a variety of roles for volunteers. Investment funds are raised from the community, to whom any profit earned from the sale of electricity to the grid is returned.

The current Brixton Energy programme builds on the success of completed solar energy projects in the area, looking into different forms of sustainable energy, such as combined heat and power (CHP) and anaerobic digestion processors, which convert wasted food into heat, cooking gas and fertiliser.

Activities include support for community meetings, mentoring sessions, solar panel-making workshops and internship placements for young people living on project sites. The ambition is to see up to 1MW of community-owned renewable energy generating capacity installed in Brixton. On behalf of Lambeth Council, Repowering London is also looking into the feasibility of installing solar power in the markets of Electric Avenue (itself a pioneer of electric lighting).

Energy Garden

The same model of community involvement is behind Repowering London's latest project, Energy Garden - a citywide scheme aiming to create a network of community gardens at London's overground rail stations. Bringing together local communities, landowners and businesses, the project is being delivered by Repowering in partnership with Groundwork London and London Overground Rail Operations.

The Energy Garden vision is for a series of green spaces where local people can come together to grow food (both for themselves and local foodbanks), share knowhow, generate and use clean energy, and improve the local environment. Funds are currently being raised for the installation of solar-powered water pumps, lights and notice boards, with income raised from the sale of surplus electricity going to support gardening projects and upkeep.

Get involved: info@repowering.org.uk

The wind in our sails

Dr Derek Taylor, our second speaker, is an expert in renewable energy - consultant on design for sustainability and visiting fellow in the Energy & Environment Research Unit at the Open University. His talk on wind energy and its use covered well over 1000 years, from the water-pumping and grain-grinding devices of ancient Persia to the latest electricity-generating wind turbines.

The earliest windmill design would hardly have been recognised by John Ashby, founder of Brixton Windmill. It was a 'panemone', a vertical axis turbine with rectangular blades pushed horizontally by the wind.

It was not until many centuries later, in the 1100s, that a windmill recognisable as the ancestor of Brixton Windmill began to appear in northwestern Europe and parts of England. Unlike the panemone, this type of windmill has blades which rotate vertically round a horizontal axis to enable maximum use of oncoming wind (now known as a horizontal-axis wind turbine, or HAWT). The earliest was the post mill, with sails fixed to the body of the mill. Later came tower mills (like Brixton Windmill), with sails attached to a rotatable cap. Up to the 19th century, along with watermills, these mills were the workhorses of industrial and agricultural Britain.

Modern wind power

The many ingenious adaptations to windmills in the early19th century represented the last fling of widespread use of wind energy for milling (in Britain and Ireland at least), as coal-powered steam engines began to take their place and stone-ground wheat fell out of favour.

We often think of the 19th century as the time when free, clean and renewable sources of energy from wind and water mills, serving a multitude of power uses from grinding grain to pumping water, gave way to 'dark satanic mills' with their engines belching toxic fumes. It was surprising to learn from Derek Taylor that the modern use of wind energy dates back as far the 1880s, when Glaswegian professor James Blyth invented a wind turbine that powered electricity to light his holiday home in Marykirk, Aberdeenshire, which he installed in his garden. (Suspicious neighbours declined the opportunity to use the new invention to light their streets, however.)

Blyth's invention was itself enabled by the development of the first accumulators (energy storage devices) by the Frenchman Camille Alphonse Faure, but never really caught on in Britain because of economic concerns.

It was a different story in Denmark, where in 1895 scientist Poul la Cour converted a windmill into a prototype electrical power plant that was used to light the village of Askov. His invention led to significant growth in the country's wind-powered electrification. By the 1960s, the country had developed a three-bladed HAWT similar to the commercial wind turbines of today. Denmark has continued to be a world leader in development of wind power.

By the 1930s, wind generators were also common on farms throughout the USA, with characteristic open lattice steel towers, building on the work of inventor Charles F Brush in Cleveland, Ohio.

The wind industry

The large-scale commercial use of wind-generated electricity for distribution has developed over the past 50 years, driven first by scarcity and uncertainty over traditional energy sources (especially oil prices) and now, increasingly, by environmental concerns.

As Derek Taylor demonstrated, the technology has made enormous advances in the same period, with turbine size and capacity increasing by many times. The design of turbines - including everything from height, shape, body and blade materials, aerodynamics, hub design, rotor span, number of blades and speed of rotation - has been the subject of intensive research and development, particularly in the USA, Denmark and China. Innovations in design and materials need to stand up to the stresses and strains that come with ever-increasing tower height, greater wind speed and turbulence.

Even the direction of rotation has changed: from anti-clockwise for the old windmills to a standard clockwise rotation today. The  HAWT (horizontal axis) has now generally triumphed over the VAWT (vertical axis) turbine, but different designs still have their champions, including some weird and wonderful designs for homes and small businesses, ranging from helix shapes to eggbeaters.

When it comes to the latest HAWTs, big is beautiful, due to economies of scale and the increase of wind speed at high altitude. Blades of up to 50 metres in length are now possible, giving a sweep the size of a football pitch. Tower heights two to three times the blade length enable blades to capture wind more efficiently. The average height is still set to rise, with offshore turbines showing the greatest increase over the past decade - although it is expected that tower height will some day reach its limit.

Challenges

What are the issues for the future? Funding (including development and investment costs) is one of them. While incentives for the development of wind and solar energy were once favoured, UK government, both local and national, is becoming more cautious (despite their obligations on carbon reduction under the Climate Change Act). 2017 saw a major slump in investment in renewable energy in the UK and a virtual ban on subsidies for onshore wind farms.

Location is a particular issue - particularly the relative costs and benefits of on- and offshore development. Derek Taylor informed us that land-based wind turbines provide the cheapest form of green energy available in Britain. But UK government policy now favours offshore development by international consortia, as do local planning authorities, concerned about having wind farms in their own backyard.

At Brixton Windmill we are often asked if wind power could be put to use again locally (especially when the sails are whizzing round on a windy National Mills Weekend). While the practicalities and economics don't necessarily work out, Derek Taylor points out that the London basin is surrounded by a ring of high ground on which powerful turbines could be sited.

More encouraging, perhaps, is the fact that the London Array off the Kent Coast - Europe's largest wind farm, opened in 2013 - now generates enough electricity for around half a million homes, equivalent to nearly two thirds of all the homes in Kent.

Another issue is the impact of wind turbines on wildlife, especially on sites of special protection. In 2014 the second phase of the London Array development, which would have seen the addition of over 160 turbines to its current 175, was refused planning consent because of concerns about its impact on a local population of rare seabirds. The Royal Society for the Protection of Birds now works closely with government and developers on the siting of new wind farms.

Finally, the short life of wind turbines (currently around 20 to 25 years) also presents a challenge. The industry has responded by working on various life extension schemes and systems for recycling turbines and repowering the sites on which they are based.

Discussion

A wide-ranging question and answer session followed the presentations of the two speakers. Questions and comments covered diverse energy-related issues, from the future of energy storage (an important concern with a fluctuating energy source) to fuel poverty and the pros and cons of other alternative energy sources for London, such as tidal energy and biodiesel from waste products (now contributing to the 'greening' of London's bus fleet). 

Reasons to be cheerful?

Recent weeks have seen bad news and good. A stark report from the IPCC (Intergovernmental Panel on Climate Change) warned that governments must make hard, urgent decisions if 'Hothouse Earth' is to be avoided. Despite this, there was no word about clean energy or climate change in the recent UK Budget (and a continuation of the freeze on fuel duty).

But national progress in the application of the latest technology, and local projects such as those of Repowering London, show that greener energy messages are now being taken very seriously by many businesses, consumers and local communities - a quiet revolution. Scottish Power, one of the big six energy suppliers, has just become the first major UK energy company to generate all its electricity from wind power, after selling its gas and hydro stations.

This leaves many burning issues and controversies to be mulled over in the future. Friends of Windmill Gardens hope that our Windmill lecture is only a beginning, and that our new education centre, due to open in April 2019, will be a venue for information and discussion about all these matters, for both children and adults - inspired by the history of Brixton Windmill.

Further information

Repowering London

Altechnica

List of onshore wind farms in UK

List of offshore wind farms in the UK

IPCC

Image - windmill_lecture_2018_composite.jpg