Na primeira unidade comercial de torre solar do mundo, uma inspiradora visão do futuro da geração de energia. O que está impedindo a adoção desta tecnologia em larga escala?
A Espanha recebe uma boa dose de radiação solar, comparada ao restante da Europa. Surpreendentemente, esta tecnologia poderia ser comparada a uma usina de geração hidrelétrica convencional "seca", já que produz vapor de água, que move as turbinas, produzindo eletricidade com água no meio do deserto.
O governo da Espanha decidiu apoiar a indústria de energia solar. Em uma usina de torre solar, a tecnologia consiste em uma fileira de enormes espelhos dispostos de maneira semicircular e uma torre muito alta. Cada espelho é controlado remotamente.
O vasto campo de espelhos é dirigido com precisão por um computador central para seguir o arco solar, à medida que o Sol cruza o céu do sul do país. O silêncio do processo é interrompido pelo som dos motores fazendo ajustes na posição de cada espelho.
Os raios solares refletidos são dirigidos a uma marca no topo da torre. Por trás desta intensa marca quente água está sendo fervida, gerando vapor. As temperaturas podem chegar a 2.000 graus.
Não obstante, a usina está operando atualmente entre 450 e 500 graus. Assim, o vapor gera eletricidade ao fazer girar as turbinas e a energia é vendida à Rede Nacional.
Esta plataforma solar tem a capacidade de fornecer eletricidade à cidade de Sevilha para cerca de 250 residências.
O coordenador da empresa Desertec no Reino Unido, Gerry Wolff, diz: "Um modelo para o mundo. É a primeira unidade comercial do planeta, cercada por plantações e laranjeiras onde mais de mil unidades com suportes de 1,3 metro chamados Helio Stats (Stats: pilhas, montes; Helio, Sol em grego) foram plantadas.
A constância do investimento inicial tem sido grande. Cada Helio Stats tem um espelho preso a um apoio motorizado, com controle remoto.
A única diferença entre geradoras a luz solar concentrada e as nucleares ou a carvão é que a matéria prima vem do Sol, evitando a queima de carvão e reações nucleares.
Como a luz solar é intermitente, existe tecnologia para estocar o calor gerado durante o dia, que utiliza tanques com sais derretidos. É relativamente fácil criar e estocar calor; a meta é ter uma usina que gere energia solar 24 horas por dia.
A usina solar impressiona por seu tamanho e escala. Enormes torres que a comunidade de investidores ainda enxerga como um risco alto estão evoluindo, e há mudanças ocorrendo com a eficiência da tecnologia na Espanha e no exterior.
Será esse plano visionário bom demais para ser verdade?
A tecnologia ainda é cara, e à medida que as usinas forem construídas de maneira mais eficiente, a eletricidade da energia solar concentrada provavelmente se tornará a fonte mais barata da Europa, incluindo os custos de transmissão.
Dificilmente teria sido construída e sobrevivido sem subsídios governamentais, o que ocorre com tecnologias renováveis, e a solar não é diferente; o investimento inicial é grande, a maior parte do dinheiro é gasta na construção das usinas; não há, porém, custos com combustíveis quando entram em operação.
A questão, então, é o apoio governamental, e no caso da Espanha, o subsídio vem em forma de tarifas de fornecimento. Durante anos os valores de venda proporcionaram ao governo preços de energia vendida à Rede Nacional pelas tecnologias solares emergentes relativamente altos.
Na década passada as células fotovoltaicas voltaram à moda, e à medida que as vendas cresceram, os custos baixaram.
Nos anos 1970 gastava-se US$ 30 por watt para fazer um painel solar. Hoje é barato, US$ 1,50 por watt pelo fabricante de menor custo - adivinhe - a China.
Células solares tradicionais absorvem um influxo de amplo espectro na conversão de luz do dia em energia.
A luz branca é composta de muitas cores diferentes, que correspondem a diferentes níveis de energia; uma parte do espectro que compõe a luz é mais energética do que o de outras cores.
A energia eletromagnética absorvível pelas células se estende do ultravioleta ao infravermelho. Para tornar as células solares mais eficientes é necessário construir absorventes capazes de coletar altas energias, além da frequência infravermelha, pouco energética.
É preciso ter várias células solares diferentes para essas cores específicas de luz. Como estes módulos geram corrente direta (DC), um dispositivo eletrônico, o "inversor", é necessário para transformar a energia em corrente alternada (AC), utilizada no funcionamento de aparelhos residenciais.
Se os custos puderem ser cortados, a Mountain Solar Cell Technology provavelmente terá um papel muito maior na produção futura de eletricidade. Calcula-se que a energia solar que atinge a Terra em um dia seja suficiente para proporcionar toda a eletricidade consumida no mundo durante um ano. Tais cálculos levaram alguns africanos que operam com energias renováveis a pensar grande.
O Desertec é um grande plano para implantar a tecnologia de energia solar nos desertos do mundo, com o potencial de suprir toda a necessidade mundial de eletricidade: http://www.desertec.org/
É um conceito, e a ideia básica é que em regiões desérticas como a do Saara há um colosso de energia vindo do céu na forma de luz solar, além do que existem agora novas tecnologias para captá-la e, a custo razoável, transformá-la em eletricidade.
Gus Schellekens, da PricewaterhouseCoopers no Reino Unido diz que muitos não percebem que a eletricidade das fontes convencionais como combustíveis fósseis, gás, carvão e, em alguma medida, a nuclear, são todas subsidiadas de alguma maneira.
No Brasil, por exemplo, usinas como a de Belo Monte são subsidiadas a juros baixíssimos do BNDES, e a diferença é paga pelo Tesouro Nacional – vulgo, o bolso do consumidor. Outro caso clássico é o subsídio cruzado, onde os usuários do sul pagam mais que os do norte do País. A sociedade banca, inclusive, a energia mais barata consumida pela indústria.
Artificialmente barata, porém, já que são todas subsidiadas. Interesses políticos e privados operam a favor dessa situação e podem entravar o crescimento do uso da energia solar.
Além das usinas solares, a Espanha é o maior usuário mundial de células fotovoltaicas. Painéis solares fotovoltaicos são feitos basicamente de silício ou outros materiais semicondutores, e criam eletricidade diretamente da radiação solar. Células solares energizam os satélites da NASA (e da Estação Espacial ISS) desde 1950.
Entraram na moda após a crise do petróleo dos anos 1970. Mas as fases de iniciativas ambiciosas caíram todas por terra quando o fluxo de petróleo barato foi retomado.
Se os custos puderem ser cortados, a empresa Mountain Solar Cell Technology deverá desempenhar um papel maior na produção futura de eletricidade. Estima-se que a energia solar que atinge a Terra em uma hora seja suficiente para suprir a demanda mundial por energia durante um ano.
A única diferença básica entre a energia solar concentrada e a gerada por usinas a carvão, nuclear, óleo, é que o calor vem do Sol; poluição zero. Ou melhor, as solares são livres de riscos, considerando a recente explosão de uma usina nuclear no Japão, após o terremoto de magnitude 8,9 Richter e o tsunami.
A luz solar é intermitente, mas existe tecnologia para estocar o calor gerado durante o dia; uma tecnologia usas tanques de sais derretidos. É relativamente fácil criar e estocar o calor e o objetivo é ter uma usina que gere energia solar 24 horas por dia.
Torres solares não são a única tecnologia para concentrar energia solar, ou CSPs. Uma alternativa é concentrá-la em tubulações cheias de óleo, onde a energia do Sol é concentrada em quase 100 vezes mais. O óleo é aquecido a até 500ºC, fervendo água, que gera vapor para girar turbinas que produzem eletricidade.
Planos para CSPs foram oferecidos na América durante décadas. No caso das usinas americanas, construídas nos anos 1980, as terras já se pagaram e eles conseguem produzir energia por cerca de US$0,03 por quilowatt, uma das mais baratas formas de energia atualmente. Mais barata que a nuclear, o carvão, ou qualquer outra fonte fóssil.
A energia Solar tem um grande papel a cumprir; é uma fonte inesgotável de suprimento, uniformemente distribuída pelo mundo, com tecnologia já existente para captá-la e transmiti-la imediatamente; a única coisa necessária é desentravar a resistência.
The world's first commercial solar tower plant gives a breathtaking glimpse of the future of power generation. What's stopping the technology's widespread adoption?
Here you see the Abengoa Solar Plant. Spain has a good solar radiation compared to the rest of Europe. Surprisingly, this technology could be compared to a "dry" conventional hidroelectric generating plant, once it produces steam, which is water vapour, that moves turbines, producing electricity from water in the middle of the desert.
The Spanish Government has decided to firmly support the solar energy industry. At a solar tower plant like this, the technology consists in a row of huge mirrors disposed in a semicircular pattern and a very tall tower. Each mirror is controlled by remote control.
The vast field of mirrors is precisely directed by a central computer to follow the arc of the Sun as it crosses the sky of southern Spain. The silence of the process is interrupted by the sound of motors making adjustments in the position of each mirror.
The reflected solar rays are targeted to the spot at the top of the tower. Behind this intense hotspot water is being boiled, generating steam. Temperatures can reach 2,000 degrees.
Not withstanding, the plant is presently operating at 450 to 500 degrees. Thus, the steam generates electricity by running the turbines and the energy is sold to the National Grid.
This Solar Platform will be able to supply electricity to the city of Seville for about 250 homes.
The UK coordinator of Desertec, Gerry Wolff, says: "A model for the world. It's the first commercial unit in the world surrounded by farmland and orange grows over a one thousand 1,3 standing units called Helio Stat (Helio comes from greek "Helium", that means Sun) have been planted. The upfront investment constancy has been very large. Each Helio Stat has a mirror attached to a remote controlled motorized stand.
The only difference between concentrated and nuclear or coal plants is that we get heat from the Sun, instead of burning coal or making nuclear reaction. Or rather, solars are risk-free, considering the explosion ocured in a nuclear plant in japan in the aftermath of the 8,9 Richter quake and tsunami.
As sunlight is intermitent, technology exists to store generated heat during the day; one technology uses tanks of molten salts.Its is relatively easy to create and store heat; the goal is to have a plant that generates solar energy 24 hours a day.
The immediate thing a visitor sees at a solar plant is the size and scale. Huge towers that the investors community still sees as a high risk are evolving and there are changes happening to the efficiency and effectiveness of the technology here and out.
Is this visionary plant too good to be true?
It' unlikely to having them been built and even to survive without government subsidize, what we find with renewable technologies and solar is not different; the upfront investment is very large, most of the money is spent with the building of the plants; but there are no fuel costs once they're operating.
The next consideration then is the support government gives to the industry, and in the case of Spain, subsidizein form of of feeding tariffs. Over a period of years feeding tariffs provided government price of energy sold to the National Grid by emerging solar technologies have been relatively expensive.
Over the past decade solar voltaics have come back into vogue and as sales go on, the cost has come down.
In the 1970s, it would cost US$ 30 per watt to make a solar panel. Now, it's very cheap, US$ 1,50 per watt from the lowest cost manufacturer - guess? - China.
Traditional solar cells take a broad spectrum approach converting daylight into energy.
White light is composed of many different colours and these colours correspond to different energies, some part of the spectrum which make up light have more energy potential than other colours.
The energy spans from ultraviolet to infrared. In order to make more efficient solar cells we have to build absorbers capable of absorbing high energy, as well as low-energy infrared frequency.
We chief it by having many different solar cells which are made to those specific colours of light.
If cost cut could be done, Mountain Solar Cell Technology is likely to play a bigger role in producing electricity in the future. It's been estimated that enough solar energy hits out in one hour is enough to provide all the world's energy needs for one year. It's calculations like this which have fired some renewable energy africans to think big. And just 1% of the world's desert areas is enough.
Political and economic realities work to help and can hinder the growth of solar energy. In addition to solar plants, Spain is the world's user of solar voltaics. Solar voltaic panels tipically made of silicon or other semiconductor materials create electricity directly from the Sun's radiation. Solar cells have been powering Nasa's satellites (and the ISS) since 1950.
They came into fashion after the oil crisis of the 1970s. But the ambitious initiatives phases all died when the flow of cheap oil resumed.
Solar towers is only one technology of concentrating solar energy, or CSPs. Another technology is to concentrate solar energy into oil filled tubes.The Sun's energy is concentrated almost 100 fold. The oil is heated up to five hundred degrees. The hot oil boils water, which generate steam to drive a turbine which produces electricity.
CSP plans have been offered in America for decades. In the case of US plants which are built in the 1980s, they have paid off their lands and they can produce electricity for arouns three US cents per kilowatt, which is among the cheapest forms of energy in the world today. Cheaper than nuclear, cheaper than coal, cheaper than any fossile fuel sources.
Solar has a huge role they can play; the fact that it has endles supply energy, the fact that it's uniformly distributed in the world; the fact that technology exists to capture and transmit at the moment means that one thing is needed to unlock much of that is a politicalship and will.
Here you see the Abengoa Solar Plant. Spain has a good solar radiation compared to the rest of Europe. Surprisingly, this technology could be compared to a "dry" conventional hidroelectric generating plant, once it produces steam, which is water vapour, that moves turbines, producing electricity from water in the middle of the desert.
The Spanish Government has decided to firmly support the solar energy industry. At a solar tower plant like this, the technology consists in a row of huge mirrors disposed in a semicircular pattern and a very tall tower. Each mirror is controlled by remote control.
The vast field of mirrors is precisely directed by a central computer to follow the arc of the Sun as it crosses the sky of southern Spain. The silence of the process is interrupted by the sound of motors making adjustments in the position of each mirror.
The reflected solar rays are targeted to the spot at the top of the tower. Behind this intense hotspot water is being boiled, generating steam. Temperatures can reach 2,000 degrees.
Not withstanding, the plant is presently operating at 450 to 500 degrees. Thus, the steam generates electricity by running the turbines and the energy is sold to the National Grid.
This Solar Platform will be able to supply electricity to the city of Seville for about 250 homes.
The UK coordinator of Desertec, Gerry Wolff, says: "A model for the world. It's the first commercial unit in the world surrounded by farmland and orange grows over a one thousand 1,3 standing units called Helio Stat (Helio comes from greek "Helium", that means Sun) have been planted. The upfront investment constancy has been very large. Each Helio Stat has a mirror attached to a remote controlled motorized stand.
The only difference between concentrated and nuclear or coal plants is that we get heat from the Sun, instead of burning coal or making nuclear reaction. Or rather, solars are risk-free, considering the explosion ocured in a nuclear plant in japan in the aftermath of the 8,9 Richter quake and tsunami.
As sunlight is intermitent, technology exists to store generated heat during the day; one technology uses tanks of molten salts.Its is relatively easy to create and store heat; the goal is to have a plant that generates solar energy 24 hours a day.
The immediate thing a visitor sees at a solar plant is the size and scale. Huge towers that the investors community still sees as a high risk are evolving and there are changes happening to the efficiency and effectiveness of the technology here and out.
Is this visionary plant too good to be true?
It' unlikely to having them been built and even to survive without government subsidize, what we find with renewable technologies and solar is not different; the upfront investment is very large, most of the money is spent with the building of the plants; but there are no fuel costs once they're operating.
The next consideration then is the support government gives to the industry, and in the case of Spain, subsidizein form of of feeding tariffs. Over a period of years feeding tariffs provided government price of energy sold to the National Grid by emerging solar technologies have been relatively expensive.
Over the past decade solar voltaics have come back into vogue and as sales go on, the cost has come down.
In the 1970s, it would cost US$ 30 per watt to make a solar panel. Now, it's very cheap, US$ 1,50 per watt from the lowest cost manufacturer - guess? - China.
Traditional solar cells take a broad spectrum approach converting daylight into energy.
White light is composed of many different colours and these colours correspond to different energies, some part of the spectrum which make up light have more energy potential than other colours.
The energy spans from ultraviolet to infrared. In order to make more efficient solar cells we have to build absorbers capable of absorbing high energy, as well as low-energy infrared frequency.
We chief it by having many different solar cells which are made to those specific colours of light.
If cost cut could be done, Mountain Solar Cell Technology is likely to play a bigger role in producing electricity in the future. It's been estimated that enough solar energy hits out in one hour is enough to provide all the world's energy needs for one year. It's calculations like this which have fired some renewable energy africans to think big. And just 1% of the world's desert areas is enough.
Political and economic realities work to help and can hinder the growth of solar energy. In addition to solar plants, Spain is the world's user of solar voltaics. Solar voltaic panels tipically made of silicon or other semiconductor materials create electricity directly from the Sun's radiation. Solar cells have been powering Nasa's satellites (and the ISS) since 1950.
They came into fashion after the oil crisis of the 1970s. But the ambitious initiatives phases all died when the flow of cheap oil resumed.
Solar towers is only one technology of concentrating solar energy, or CSPs. Another technology is to concentrate solar energy into oil filled tubes.The Sun's energy is concentrated almost 100 fold. The oil is heated up to five hundred degrees. The hot oil boils water, which generate steam to drive a turbine which produces electricity.
CSP plans have been offered in America for decades. In the case of US plants which are built in the 1980s, they have paid off their lands and they can produce electricity for arouns three US cents per kilowatt, which is among the cheapest forms of energy in the world today. Cheaper than nuclear, cheaper than coal, cheaper than any fossile fuel sources.
Solar has a huge role they can play; the fact that it has endles supply energy, the fact that it's uniformly distributed in the world; the fact that technology exists to capture and transmit at the moment means that one thing is needed to unlock much of that is a politicalship and will.
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