Produção de energia verde durante o dia e a noite, sem baterias, baseada no armazenamento em sais fundidos.

Energia para o futuro: por que instalações como a torre solar de Dunhuang, na China, são importantes para o setor energético e para o planeta.

No vasto deserto de Gobi, próximo a Dunhuang, na província de Gansu, no noroeste da China, encontra-se um exemplo impressionante do que a energia renovável moderna pode realizar: uma usina heliotérmica de concentração solar em torre, com sais fundidos e capacidade de 100 MW. Cercada por aproximadamente 12 mil grandes espelhos controlados por computador — chamados heliostatos —, essa instalação consegue fazer algo que os painéis solares convencionais não fazem: gerar eletricidade limpa não apenas durante o dia, mas também por várias horas durante a noite.

O sistema funciona concentrando a luz solar em um receptor central situado no alto de uma torre com aproximadamente 260 metros de altura. O calor intenso eleva a temperatura dos sais fundidos para mais de 560°C. Esses sais aquecidos são armazenados em tanques termicamente isolados e posteriormente utilizados para produzir vapor, que movimenta turbinas.

Com capacidade de armazenamento térmico suficiente para sustentar muitas horas de geração depois do pôr do sol — geralmente citadas como cerca de 11 horas nas condições previstas em projeto —, a usina pode fornecer eletricidade de maneira estável e despachável durante o dia e a noite. Ela ocupa vários quilômetros quadrados, produz aproximadamente 390 GWh de eletricidade por ano — quantidade comparável ao consumo de cerca de 100 mil residências — e está em operação comercial desde o final de 2018.

Produção confiável de energia em um mundo de fontes variáveis.

A energia solar fotovoltaica tradicional é intermitente: sua produção cai a zero quando o sol se põe e diminui quando nuvens encobrem o céu. O armazenamento em baterias pode ajudar, mas o armazenamento térmico em grande escala por meio de sais fundidos oferece uma alternativa comprovada e de longa duração, compatível com a tecnologia já estabelecida das turbinas a vapor.

Instalações como a de Dunhuang transformam a energia solar em um recurso com maior capacidade de fornecer energia de base. Essa confiabilidade é fundamental à medida que cresce a demanda de eletricidade para residências, indústrias, veículos elétricos, centros de processamento de dados e eletrificação dos sistemas de aquecimento e transporte.

Ao fornecer eletricidade previsível durante o dia e a noite, essas usinas reduzem a necessidade de geração de reserva baseada em combustíveis fósseis e ajudam a estabilizar redes elétricas que incorporam proporções cada vez maiores de fontes renováveis variáveis.

Essa tecnologia também demonstra uma inovação que pode ser ampliada. Projetos semelhantes de concentração solar com sais fundidos estão avançando em outras regiões, mostrando que áreas ensolaradas e áridas podem abrigar grandes usinas renováveis de elevada capacidade, complementando parques eólicos e fotovoltaicos.

Em uma época de necessidades energéticas crescentes e de busca por segurança energética, a geração limpa e despachável não é opcional: ela é essencial.

Benefícios evidentes para a saúde ambiental.

Cada megawatt-hora gerado por essa usina substitui eletricidade proveniente de combustíveis fósseis e as emissões associadas a ela. A produção anual projetada de aproximadamente 390 GWh corresponderia a evitar cerca de 350 mil toneladas de dióxido de carbono por ano — efeito comparável à retirada de dezenas de milhares de automóveis das estradas.

Além do CO₂, a usina reduz outros poluentes atmosféricos associados às centrais movidas a carvão e gás, contribuindo para melhorar a qualidade do ar, a saúde pública e as condições ambientais em escalas local e regional.

Como a energia é armazenada na forma de calor nos sais, em vez de depender da queima contínua de combustível, a usina opera com emissões diretas próximas de zero depois de construída. Sua localização em área desértica reduz a competição por terras agrícolas ou áreas com ecossistemas densos, enquanto o circuito fechado dos sais fundidos limita o consumo de água em comparação com algumas centrais térmicas convencionais.

Ao longo de sua vida útil, a instalação contribui para reduzir o acúmulo de gases de efeito estufa na atmosfera, ajudando a mitigar riscos climáticos como eventos meteorológicos extremos, aumento das temperaturas e pressões sobre os ecossistemas.

Um caminho prático para o futuro.

A usina de Dunhuang é mais do que uma vitrine tecnológica. Ela demonstra que já dispomos de soluções funcionais para produzir grandes quantidades de eletricidade limpa e confiável enquanto reduzimos os impactos ambientais.

A expansão de instalações semelhantes — combinada com melhorias na eficiência energética, outras fontes renováveis e redes elétricas inteligentes — pode acelerar o afastamento das fontes com elevadas emissões. O resultado será a construção de sistemas energéticos capazes de sustentar a atividade econômica e o bem-estar humano sem os danos cumulativos causados pela poluição dos combustíveis fósseis e pelas emissões de carbono.

Em resumo, usinas como essa são importantes porque demonstram que a energia renovável pode ser simultaneamente abundante e confiável. Elas fornecem eletricidade quando as pessoas precisam e, ao mesmo tempo, reduzem os impactos ambientais da geração energética.

Expandir e aperfeiçoar essas tecnologias constitui uma das medidas mais concretas disponíveis para alcançar um ar mais limpo, um clima mais estável e um abastecimento energético seguro nas próximas décadas.

Avaliação geral

O texto é tecnicamente bem fundamentado, mas excessivamente promocional. A usina de Dunhuang é real, relevante e demonstra que a energia solar térmica pode ser armazenada e despachada depois do pôr do sol. Entretanto, o texto mistura:

• capacidade nominal com geração efetiva;
• geração noturna com fornecimento garantido 24 horas;
• emissões operacionais com emissões de ciclo de vida;
• armazenamento térmico com inexistência de qualquer limitação de armazenamento;
• estimativas promocionais de CO₂ evitado com valores diretamente medidos.

Minha avaliação seria: essencialmente verdadeiro, mas com várias ressalvas importantes e algumas afirmações enganosas.

Checagem dos principais dados

Afirmação	Avaliação	Correção ou ressalva
Usina solar de torre com 100 MW	Correta	Trata-se da Shouhang Dunhuang Phase II, uma instalação CSP de 100 MW elétricos.
Cerca de 12.000 heliostatos	Correta	A base técnica registra 12.121 heliostatos, cada um com aproximadamente 116 m².
Torre com cerca de 260 metros	Correta	A altura informada é 263 metros.
Sal aquecido acima de 560°C	Correta	A temperatura nominal passa de cerca de 290°C na entrada para 565°C na saída do receptor.
Armazenamento por 11 horas	Correta	São 11 horas equivalentes de operação nominal, segundo o projeto.
Geração durante a noite	Correta	O calor armazenado pode produzir vapor e eletricidade depois do pôr do sol.
Energia “dia e noite”	Parcialmente correta	Isso é possível em condições favoráveis, mas não significa geração contínua garantida todos os dias do ano.
390 GWh anuais	Valor de projeto/promocional	Algumas fontes divulgam 390 GWh; a base SolarPACES/NLR registra uma expectativa original ainda maior, de 483 GWh/ano. A produção real esteve abaixo desses valores em diversos anos.
Operação comercial desde 2018	Quase correta	Foi conectada à rede em dezembro de 2018, mas só alcançou operação em plena carga em junho de 2019.
Área de vários km²	Correta	A área total declarada é aproximadamente 8 km², com 1,4 milhão de m² de superfície refletora.
Abastece 100.000 residências	Plausível, mas ilustrativo	Depende muito do consumo residencial adotado e não significa que determinadas casas sejam alimentadas diretamente pela usina.
Evita 350 mil toneladas de CO₂ por ano	Estimativa condicionada	Esse número pressupõe geração próxima de 390 GWh e substituição de eletricidade muito intensiva em carvão. Não é uma quantidade fixa nem diretamente medida.
Sistema de sal em circuito fechado reduz o consumo de água	Formulação incorreta	O circuito fechado reduz a reposição de sal, mas o consumo de água depende principalmente da refrigeração do ciclo de vapor e da lavagem dos espelhos. Dunhuang usa refrigeração seca, e é isso que reduz substancialmente o consumo de água.

Os parâmetros técnicos principais podem ser conferidos na base internacional SolarPACES/NLR. O histórico de construção e operação também é descrito no artigo técnico dos responsáveis pela instalação.

O que significa realmente “11 horas de armazenamento”

O título “energia verde dia e noite, sem baterias” contém uma verdade, mas pode induzir a uma conclusão exagerada.

A usina não usa grandes baterias eletroquímicas para guardar a energia principal. Ela armazena calor sensível em dois tanques:

1. O sal relativamente “frio”, a aproximadamente 290°C, é bombeado até o receptor.
2. A radiação solar concentrada o aquece até aproximadamente 565°C.
3. O sal quente é conduzido ao tanque de armazenamento.
4. Quando se deseja gerar eletricidade, seu calor produz vapor.
5. O vapor aciona uma turbina convencional.
6. O sal resfriado retorna ao primeiro tanque.

As 11 horas significam, aproximadamente, que o estoque térmico completamente carregado pode sustentar a turbina em sua potência nominal por esse período. Isso não quer dizer que a usina produza 100 MW durante as horas solares e depois mais 100 MW por 11 horas sem limitações. Parte da radiação captada durante o dia precisa ser destinada ao carregamento do armazenamento.

Também existem:

• perdas ópticas nos espelhos;
• perdas térmicas no receptor, tubulações e tanques;
• perdas no ciclo vapor–turbina;
• consumo interno de bombas, rastreamento, controle e aquecimento;
• períodos de manutenção;
• redução de produção por nuvens, poeira e baixa insolação;
• necessidade de impedir que o sal esfrie e solidifique.

Portanto, a melhor formulação seria:

“A usina pode deslocar parte significativa da geração solar para a noite e, em condições adequadas, manter geração contínua por longos períodos sem depender de grandes baterias eletroquímicas.”

O problema dos 390 GWh

Uma usina de 100 MW que gerasse 390 GWh por ano teria fator de capacidade de:

100 MW×8.760 h390.000 MWh​≈44,5%

Esse é um resultado tecnicamente possível para uma CSP com armazenamento, mas não deve ser apresentado automaticamente como produção real.

Há uma inconsistência importante entre fontes:

• materiais promocionais citam aproximadamente 390 GWh/ano;
• a base SolarPACES/NLR registra 483 GWh/ano como geração esperada;
• dados operacionais divulgados pela indústria indicam cerca de 200 GWh em 2021 e aproximadamente 235 GWh em um ano posterior, mostrando que a curva de aprendizagem e os problemas operacionais foram relevantes.

Assim, o texto deveria dizer “produção anual projetada”, não simplesmente “produz 390 GWh”. Esse cuidado é especialmente importante porque projetos CSP pioneiros frequentemente levam anos para atingir desempenho estável.

É realmente energia de base?

“Baseload-capable” não é a melhor expressão. A usina é mais corretamente classificada como despachável dentro dos limites do estoque térmico e da insolação acumulada.

Ela pode:

• gerar no início da noite, quando a demanda costuma permanecer elevada;
• reduzir rampas bruscas causadas pelo pôr do sol;
• deslocar energia entre diferentes horas;
• contribuir com inércia rotacional e outros serviços associados à turbina;
• complementar energia fotovoltaica e eólica.

Mas não equivale a uma fonte permanentemente firme como uma hidrelétrica com reservatório amplo, uma usina nuclear ou uma termelétrica com combustível disponível. Depois de vários dias com insolação direta insuficiente, o armazenamento se esgota.

Além disso, CSP precisa principalmente de radiação solar direta. Luz difusa em dias nublados, que ainda pode gerar alguma eletricidade em painéis fotovoltaicos, não pode ser concentrada eficientemente pelos heliostatos.

Emissões evitadas: número possível, mas não universal

A estimativa de 350 mil toneladas dividida por 390 GWh corresponde a aproximadamente:

897 kg de CO₂ por MWh

Esse valor é compatível com a substituição de geração a carvão relativamente intensiva em carbono. Porém, a emissão efetivamente evitada depende da fonte marginal da rede:

• se deslocar carvão, a redução pode ser elevada;
• se deslocar gás natural, será menor;
• se a rede já estiver recebendo grande volume de renováveis ou houver restrições de transmissão, será ainda menor;
• se houver redução forçada de outra fonte renovável, o benefício marginal pode ser pequeno.

Por isso, “cada MWh desloca geração fóssil” é categórico demais. O correto seria: “cada MWh pode deslocar geração fóssil, dependendo da operação da rede.”

Também não existem emissões absolutamente nulas. Construção da torre, concreto, aço, fabricação dos espelhos, sais, turbina, manutenção e substituição de equipamentos produzem emissões. Estudos do ciclo de vida colocam CSP em uma faixa baixa, comparável a outras fontes de baixo carbono, mas não em zero. Estimativas do Departamento de Energia dos EUA situaram sistemas CSP em aproximadamente 24–28 g CO₂ equivalente/kWh, muito abaixo do carvão, mas acima de “zero” (DOE SunShot Vision Study).

Também seria mais correto dizer que a usina evita novas emissões, e não que necessariamente “reduz as concentrações atmosféricas” de gases de efeito estufa. Reduzir a concentração já existente exigiria emissões líquidas negativas.

Água e impactos ambientais

O texto acerta ao sugerir que Dunhuang consome menos água do que muitas usinas térmicas convencionais, mas erra ao atribuir isso ao circuito fechado do sal.

A usina utiliza refrigeração seca, confirmada na ficha técnica do projeto. Isso reduz drasticamente a água usada para condensar o vapor. Estudos estimam que refrigeração seca possa reduzir o consumo hídrico de CSP em aproximadamente 71–78% frente à refrigeração úmida.

Ainda assim, água continua sendo necessária para:

• limpeza de mais de 12 mil espelhos;
• produção e reposição de água do ciclo vapor;
• serviços e manutenção;
• controle de poeira em determinadas operações.

A refrigeração seca também tem um preço: custa mais e pode reduzir a eficiência da turbina em dias muito quentes.

O deserto, por sua vez, não deve ser tratado como espaço ambientalmente vazio. Uma instalação de aproximadamente 8 km² pode causar:

• fragmentação de habitats áridos;
• alteração do solo e da drenagem;
• impacto sobre aves e insetos próximos ao receptor;
• glare ou ofuscamento;
• necessidade de estradas e linhas de transmissão;
• consumo de materiais e perturbação durante a construção.

Provavelmente esses impactos são muito menores do que os danos climáticos e atmosféricos causados pelo carvão, mas precisam entrar na comparação.

Limitação econômica omitida

A maior ausência do texto é o custo. CSP com armazenamento é valiosa, mas normalmente custa mais que energia fotovoltaica ou eólica sem armazenamento. A base SolarPACES registra para Dunhuang:

• investimento aproximado de US$ 458 milhões em valores de 2020;
• custo específico próximo de US$ 4.582/kW;
• tarifa remunerada originalmente equivalente a cerca de US$ 0,17/kWh;
• apoio pelo programa chinês de demonstração.

A Agência Internacional de Energia reconhece o valor sistêmico da CSP, mas observa que custos elevados, risco tecnológico, financiamento e complexidade de construção limitaram sua expansão. A comparação justa, porém, não deve ser apenas “CSP versus painel fotovoltaico”. Deve ser:

CSP com 8–15 horas de armazenamento versus fotovoltaica mais bateria, reforço da rede, geração de reserva e serviços de estabilidade.

Para armazenamento curto, a combinação fotovoltaica–bateria frequentemente é mais econômica. Para armazenamento noturno prolongado, CSP pode continuar competitiva em regiões com insolação direta excepcional. A própria IEA destaca tanto seu custo maior quanto seu valor como fonte despachável.

Conclusão crítica

A usina de Dunhuang é uma conquista importante, mas não prova que a solar térmica seja uma solução universal nem que possa fornecer eletricidade ininterrupta sem restrições. O que ela demonstra é algo mais preciso e ainda muito valioso:

Em regiões com forte radiação solar direta, uma usina CSP pode armazenar grandes quantidades de energia como calor a custo potencialmente competitivo para longas durações, transferir geração do dia para a noite e complementar energia fotovoltaica, eólica, hidrelétrica, nuclear e outras fontes firmes.

Portanto, a mensagem central do texto deve ser preservada, mas “energia abundante e confiável 24 horas” deveria ser substituída por “energia solar parcialmente despachável, com armazenamento térmico de longa duração”. Essa formulação é menos espetacular, porém cientificamente mais defensável.

Day and night green energy production without batteries, based on molten salt storage.

Powering Tomorrow: Why Facilities Like China’s Dunhuang Solar Tower Matter for Energy and the Planet.

In the vast Gobi Desert near Dunhuang in northwest China’s Gansu Province stands a striking example of what modern renewable energy can achieve: a 100 MW molten-salt tower concentrated solar power (CSP) plant. Surrounded by roughly 12,000 large, computer-controlled mirrors (heliostats), this facility does something conventional solar panels cannot—it generates clean electricity not only during daylight hours but well into the night.

The system works by focusing sunlight onto a central receiver atop a towering structure about 260 meters high. The intense heat raises molten salt to temperatures exceeding 560°C. That hot salt is stored in insulated tanks and later used to produce steam that drives turbines. With thermal storage capacity supporting many hours of generation after sunset (commonly cited around 11 hours under design conditions), the plant can deliver steady, dispatchable power around the clock. It covers several square kilometers, produces on the order of 390 GWh of electricity annually, consumption of approximately 100,000 households, and has been operating commercially since late 2018.

Reliable Energy Production in a Variable World

Traditional photovoltaic solar is intermittent—output drops to zero when the sun sets or clouds gather. Battery storage can help, but large-scale thermal storage in molten salt offers a proven, long-duration alternative that pairs well with existing steam-turbine technology. Facilities like Dunhuang turn solar energy into a more baseload-capable resource. This reliability is critical as electricity demand grows for homes, industry, electric vehicles, data centers, and electrification of heating and transport. By providing predictable power day and night, such plants reduce the need for fossil-fuel backup generation and help stabilize grids that integrate increasing shares of variable renewables.

The technology also demonstrates scalable innovation. Similar molten-salt CSP projects are advancing elsewhere, showing that sunny, arid regions can host large, high-capacity renewable plants that complement wind and photovoltaic farms. In an era of rising energy needs and the push for energy security, dispatchable clean power is not optional—it is essential.

Clear Benefits for Environmental Health

Every megawatt-hour generated by this plant displaces fossil-fuel generation and its associated emissions. Designed annual output of roughly 390 GWh equates to avoiding approximately 350,000 tons of carbon dioxide each year—comparable to taking tens of thousands of cars off the road. Beyond CO₂, it reduces other air pollutants linked to coal and gas plants, improving local and regional air quality and public health.

Because the energy carrier is heat stored in salt rather than continuously burning fuel, the plant operates with near-zero operational emissions once built. Land use in desert areas minimizes competition with agriculture or dense ecosystems, and the closed-loop nature of the molten-salt system limits water consumption compared with some conventional thermal plants. Over its lifetime, the facility contributes to lower greenhouse-gas concentrations, helping mitigate climate risks such as extreme weather, rising temperatures, and ecosystem stress.

A Practical Path Forward

The Dunhuang plant is more than a technological showcase. It illustrates that we already possess workable solutions for producing substantial amounts of clean, reliable electricity while protecting the environment. Scaling similar facilities—alongside efficiency improvements, other renewables, and smart grids—can accelerate the shift away from high-emission sources. The result is energy systems that support economic activity and human well-being without the cumulative damage of fossil-fuel pollution and carbon emissions.

In short, plants like this one matter because they prove renewable energy can be both abundant and dependable. They deliver power when people need it and simultaneously reduce the environmental burden of electricity generation. Expanding and refining such technologies is one of the most concrete steps available toward cleaner air, a more stable climate, and secure energy supplies for the decades ahead.

Overall Assessment

The text is technically well grounded but overly promotional. The Dunhuang plant is real, relevant, and demonstrates that solar thermal energy can be stored and dispatched after sunset. However, the text conflates:

• Nominal capacity with actual generation;

• Nighttime generation with guaranteed 24-hour supply;

• Operational emissions with life-cycle emissions;

• Thermal storage with the absence of storage limitations;

• Promotional estimates of avoided CO₂ with directly measured values.

My assessment would be: essentially true, but with several important caveats and some misleading claims.

Fact-Checking the Main Figures

Claim	Assessment	Correction or caveat
100 MW solar tower plant	Correct	This is the Shouhang Dunhuang Phase II, a 100 MW electrical CSP facility.
Approximately 12,000 heliostats	Correct	The technical database lists 12,121 heliostats, each with an area of approximately 116 m².
Tower approximately 260 meters high	Correct	The reported height is 263 meters.
Salt heated to more than 560°C	Correct	The nominal temperature rises from approximately 290°C at the receiver inlet to 565°C at the outlet.
11 hours of storage	Correct	The plant was designed for 11 equivalent hours of operation at nominal output.
Electricity generation at night	Correct	The stored heat can produce steam and electricity after sunset.
Energy “day and night”	Partly correct	This is possible under favorable conditions, but it does not mean guaranteed continuous generation every day of the year.
390 GWh annually	Projected/promotional figure	Some sources cite 390 GWh, while the SolarPACES/NLR database records an even higher original expectation of 483 GWh per year. Actual production remained below these values in several years.
Commercial operation since 2018	Almost correct	The plant was connected to the grid in December 2018 but reached full-load operation only in June 2019.
Covers several square kilometers	Correct	The reported total site area is approximately 8 km², with 1.4 million m² of reflective surface.
Supplies 100,000 households	Plausible but illustrative	This depends heavily on the assumed household electricity consumption and does not mean that specific homes are supplied directly by the plant.
Avoids 350,000 tonnes of CO₂ per year	Conditional estimate	This assumes generation close to 390 GWh and the replacement of highly carbon-intensive coal-fired electricity. It is neither a fixed amount nor a directly measured figure.
Closed-loop salt system reduces water consumption	Incorrectly formulated	The closed loop reduces salt replacement, but water consumption depends mainly on cooling the steam cycle and cleaning the mirrors. Dunhuang uses dry cooling, which is what substantially reduces water use.

The main technical parameters can be verified in the international SolarPACES/NLR database. The plant’s construction and operating history are also described in a technical paper written by people involved in the project.

What “11 Hours of Storage” Really Means

The headline “green energy day and night, without batteries” contains an element of truth but may lead readers to an exaggerated conclusion.

The plant does not use large electrochemical batteries to store its main energy supply. Instead, it stores sensible heat in two tanks:

1. The relatively “cold” salt, at approximately 290°C, is pumped to the receiver.

2. Concentrated solar radiation heats it to approximately 565°C.

3. The hot salt is transferred to the storage tank.

4. When electricity is required, its heat is used to produce steam.

5. The steam drives a conventional turbine.

6. The cooled salt returns to the first tank.

The 11-hour figure means, approximately, that a fully charged thermal store can sustain the turbine at its nominal output for that period. It does not mean that the plant can produce 100 MW during daylight and then another 100 MW for 11 hours without constraints. Part of the solar radiation captured during the day must be used to charge the storage system.

There are also:

• Optical losses from the mirrors;

• Thermal losses from the receiver, pipes, and tanks;

• Losses in the steam-turbine cycle;

• Internal electricity consumption by pumps, tracking systems, controls, and heating equipment;

• Maintenance periods;

• Reduced production due to clouds, dust, and low solar irradiance;

• A need to prevent the molten salt from cooling and solidifying.

A more accurate formulation would therefore be:

“The plant can shift a substantial portion of solar generation into the nighttime and, under suitable conditions, maintain continuous generation for extended periods without relying on large electrochemical batteries.”

The Problem with the 390 GWh Figure

A 100 MW plant generating 390 GWh per year would have a capacity factor of:

[
\frac{390{,}000\ \text{MWh}}{100\ \text{MW}\times8{,}760\ \text{hours}} \approx 44.5%
]

This is technically possible for a CSP plant with thermal storage, but it should not automatically be presented as actual production.

There is an important inconsistency among the sources:

• Promotional material cites approximately 390 GWh per year;

• The SolarPACES/NLR database records 483 GWh per year as the expected generation;

• Operational data reported by the industry indicate approximately 200 GWh in 2021 and around 235 GWh in a later year, showing that the learning curve and operating problems were significant.

The text should therefore say “projected annual generation,” rather than simply stating that the plant “produces 390 GWh.” This distinction is especially important because pioneering CSP projects frequently take several years to achieve stable performance.

Is It Really Baseload Power?

“Baseload-capable” is not the best expression. The plant is more accurately described as dispatchable within the limits of its thermal reserve and accumulated solar input.

It can:

• Generate electricity during the early evening, when demand often remains high;

• Reduce steep output declines associated with sunset;

• Shift energy between different hours;

• Provide rotational inertia and other services associated with a steam turbine;

• Complement photovoltaic and wind generation.

However, it is not equivalent to a permanently firm source such as a hydroelectric plant with a large reservoir, a nuclear power station, or a thermal plant with fuel readily available. After several days of insufficient direct sunlight, the stored thermal energy will be depleted.

Furthermore, CSP primarily requires direct solar radiation. Diffuse light on cloudy days—which can still generate some electricity in photovoltaic panels—cannot be efficiently concentrated by heliostats.

Avoided Emissions: A Possible but Non-Universal Figure

Dividing the estimated 350,000 tonnes of avoided CO₂ by 390 GWh gives approximately:

[
897\ \text{kg of CO₂ per MWh}
]

This value is compatible with replacing relatively carbon-intensive coal-fired generation. However, the amount of emissions actually avoided depends on the marginal source operating on the grid:

• If the plant displaces coal, the reduction can be substantial;

• If it displaces natural gas, the reduction will be smaller;

• If the grid already receives large volumes of renewable electricity or faces transmission constraints, the reduction may be smaller still;

• If another renewable source is curtailed instead, the marginal benefit may be limited.

For this reason, the statement that “every MWh displaces fossil-fuel generation” is too categorical. A more accurate statement would be: “Every MWh may displace fossil-fuel generation, depending on grid conditions and operation.”

Nor are emissions absolutely zero. Construction of the tower, production of concrete and steel, manufacture of the mirrors, production of the salts and turbine, maintenance, and replacement of equipment all generate emissions. Life-cycle studies place CSP within a low-emissions range comparable to other low-carbon sources, but not at zero. Estimates by the US Department of Energy put CSP systems at approximately 24–28 g of CO₂ equivalent per kWh, far below coal but above zero (DOE SunShot Vision Study).

It would also be more accurate to say that the plant avoids additional emissions, rather than necessarily “reducing atmospheric greenhouse-gas concentrations.” Reducing concentrations that have already accumulated would require net-negative emissions.

Water Use and Environmental Impacts

The text is correct in suggesting that Dunhuang consumes less water than many conventional thermal power plants, but it incorrectly attributes this advantage to the closed-loop salt system.

The plant uses dry cooling, as confirmed by the project’s technical documentation. This drastically reduces the amount of water needed to condense the steam. Studies estimate that dry cooling can reduce CSP water consumption by approximately 71–78% compared with wet cooling.

Even so, water is still needed for:

• Cleaning more than 12,000 mirrors;

• Producing and replenishing water for the steam cycle;

• Services and maintenance;

• Dust control during certain operations.

Dry cooling also comes at a price: it costs more and may reduce turbine efficiency on very hot days.

The desert should not be treated as an environmentally empty space. A facility covering approximately 8 km² may cause:

• Fragmentation of arid habitats;

• Changes to soil and drainage;

• Effects on birds and insects near the receiver;

• Glare;

• The need for roads and transmission lines;

• Material consumption and disturbance during construction.

These impacts are probably far smaller than the climatic and atmospheric damage caused by coal, but they still need to be included in the comparison.

The Omitted Economic Limitation

The greatest omission in the text is cost. CSP with storage is valuable, but it normally costs more than photovoltaic or wind power without storage. The SolarPACES database reports the following figures for Dunhuang:

• An investment of approximately US$458 million in 2020 values;

• A specific cost of around US$4,582 per kW;

• An original remuneration tariff equivalent to approximately US$0.17 per kWh;

• Support through China’s demonstration program.

The International Energy Agency recognizes the systemic value of CSP but notes that high costs, technological risks, financing difficulties, and construction complexity have limited its expansion. However, the fair comparison is not simply “CSP versus photovoltaic panels.” It should be:

CSP with 8–15 hours of thermal storage versus photovoltaics plus batteries, grid reinforcement, backup generation, and grid-stability services.

For short-duration storage, the photovoltaic-battery combination is frequently more economical. For prolonged nighttime storage, CSP may remain competitive in regions with exceptionally strong direct solar radiation. The IEA highlights both its higher cost and its value as a dispatchable resource.

Critical Conclusion

The Dunhuang plant is an important achievement, but it does not prove that solar thermal energy is a universal solution or that it can provide uninterrupted electricity without constraints. What it demonstrates is something more precise and still highly valuable:

In regions with strong direct solar radiation, a CSP plant can store large amounts of energy as heat at a potentially competitive cost for long-duration storage, shift generation from daytime to nighttime, and complement photovoltaic, wind, hydroelectric, nuclear, and other firm energy sources.

The text’s central message should therefore be preserved, but “abundant and dependable 24-hour energy” should be replaced with “partly dispatchable solar energy with long-duration thermal storage.” This wording is less spectacular but scientifically more defensible.

 

Liberal Capitalism Versus Communist or Socialist Capitalism.

The Paradox of Homeownership: Why Former Socialist Countries Have More Homeowners Than Many Liberal Economies.

Private property, asset distribution, and the different paths to residential security.

There is an apparent contradiction in the contemporary world. Countries that present themselves as the ultimate defenders of private property do not always have the highest proportions of families owning the homes they live in. Conversely, many socialist countries, or those that have transitioned through socialist regimes, exhibit extraordinarily high rates of homeownership.

How can this paradox be explained?

The answer requires separating two things that are frequently confused: the legal protection of private property and the actual distribution of property among the population.

An economy can intensely protect the right to buy, sell, rent, inherit, and accumulate real estate, while keeping a large portion of the population permanently locked out of property ownership. Another economy can restrict the housing market during a certain period and subsequently transfer a large volume of housing to the families who already occupied it.

It was primarily this second process that occurred in many socialist and post-socialist countries.

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There Are Not Just Two Capitalisms

It is tempting to divide the world into two fundamental models: on one hand, liberal capitalism, characterized by a reduced state and broad marketization; on the other, what we might informally call "communist capitalism," with a strong state presence and economic competition in sectors not directly controlled by the government.

This classification captures an important difference, but it needs refinement.

The expression "communist capitalism" is a strict contradiction. Classical communism proposes precisely the overcoming of capitalism, of the private ownership of the means of production, and, in its final formulation, of the State itself.

To describe economies like China's or certain post-socialist experiences, more appropriate expressions include:

• State capitalism

• Market socialism

• State-directed mixed economy

• Market economy under centralized political direction

Nor is there a single liberal capitalism. There are profound differences between American capitalism, the Scandinavian social-democratic model, the German social market economy, and the East Asian systems oriented toward state-led development.

Therefore, rather than two pure systems, a spectrum exists. At one extreme, market coordination predominates; at the other, state coordination. Most real economies combine elements of both.

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Private Property Does Not Mean Popular Property

Liberal capitalism primarily protects the freedom to own and trade property. This does not mean property will be broadly distributed.

In a liberalized housing market, acquiring a home normally depends on:

• Sufficient income

• Savings for a down payment

• Access to credit

• The ability to pay interest for decades

• Professional stability

• Housing availability

• The ability to compete with investors and owners of multiple units

The formal freedom to buy a home can coexist with the economic impossibility of doing so.

A family may have full legal rights to private property and still spend their entire life paying rent because housing prices have grown faster than their income.

At the same time, corporations, investment funds, and high-income individuals can accumulate multiple properties. In this case, there is a great deal of private property, but it is concentrated in a relatively small fraction of society.

It is possible, therefore, to have a system profoundly favorable to private property without a society of small property owners existing.

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How Housing Worked in Socialist Countries

Under former socialist regimes, a large share of urban housing was built or managed by the state, municipalities, public enterprises, or cooperatives.

The occupant generally did not own the property as a fully negotiable asset. In exchange, they received an extremely stable right of occupancy, often of indefinite duration and, in practice, transmissible to their family.

Rents were low and did not correspond to the commercial value of the building or the land. Housing was understood primarily as a use value, rather than as an investment intended for capital appreciation.

The system had considerable problems:

• Long waiting lists for housing

• Shortages in certain regions

• Low freedom of choice

• Bureaucracy

• Standardized units

• Insufficient maintenance

• Difficulty moving to another city or expanding one's residence

Despite this, residents were relatively protected against evictions driven by rent increases and against real estate speculation.

They were not necessarily owners in a strict legal sense, but they possessed a residential security that, in some respects, approximated ownership.

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The Great Housing Privatization

With the collapse of European socialist regimes, especially during the 1990s, the new governments inherited a massive stock of state or municipal apartments.

Instead of selling all these properties to investors at the highest possible price, many countries transferred them directly to their occupants. In some cases, homes were sold for symbolic or heavily subsidized prices; in others, they were given away for free.

In Ukraine, for example, free housing privatization was adopted in favor of residents. The World Bank Blogs describes the process as a direct transfer of state properties to the families already occupying them.

This process can be called distributive privatization.

It was not simply the passage of state assets to the private sector. It was the transformation of millions of residents into homeowners.

The ECOSCOPE observes that over 70% of families in several Central and Eastern European countries own their homes without a mortgage. The organization directly links this outcome to the privatization of state housing during the transition to a market economy in the early 1990s.

This historical origin helps explain why countries like Romania, Slovakia, Hungary, and Croatia exhibit homeownership rates far superior to those of some richer liberal economies.

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The European Numbers

In 2024, approximately 68% of the European Union population lived in a home belonging to their own household.

In Romania, this proportion reached 94%; in Slovakia, 93%; in Hungary, 92%; and in Croatia, 91%. All of these countries share historical experiences tied to state socialism.

In Germany, by contrast, 53% of the population lived in rented housing. In Austria, it was 46%, and in Denmark, 39% (European Commission).

This does not mean Romania or Slovakia are necessarily more prosperous or offer better housing conditions than Germany, Austria, or Denmark.

It simply means the structure of residential property is different.

In many European liberal capitalist countries, renting is socially accepted, legally protected, and supported by public policies, cooperatives, or housing associations. A person can live in the same property for decades without considering tenancy a necessarily temporary situation.

In post-socialist countries, by contrast, mass privatization drastically reduced the public rental stock and made homeownership the dominant regime.

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The Chinese Variant

China underwent a similar process, though embedded in a different economic trajectory.

During part of the socialist period, much urban housing was provided by work units and state-owned enterprises. Reforms initiated in the late 1980s and deepened in the 1990s allowed a large portion of these homes to be sold to workers at reduced prices.

According to eLibrary IMF studies, the 1988 reform stimulated housing privatization, and a significant share of rental properties belonging to state enterprises was sold to workers at low prices. Subsequent reforms gradually ended the old enterprise-provided housing system and created a broader residential market.

China's high homeownership rate did not result solely from the spontaneous operation of the market. It was partially constructed through an initial mass transfer of assets and residential rights.

Subsequently, however, housing itself transformed into an important form of investment, savings, and speculation. The country thus transitioned from a predominantly distributive system to a complex combination of family property, state direction, and a real estate market.

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Homeownership Can Conceal Poverty

A high homeownership rate should not be confused with a high quality of life.

A person may fully own an apartment and still lack sufficient income to:

• Renovate it

• Replace electrical installations

• Improve thermal insulation

• Pay condo fees

• Adapt the residence for old age

• Move to a region with more job opportunities

The ECOSCOPE highlights that a large portion of Central and Eastern European housing stock is old and suffers from quality issues. Many families became homeowners but lack the resources to carry out necessary maintenance and modernization.

Romania illustrates this difference well. Although 94% of the population lived in owner-occupied housing in 2024, approximately 41% lived in conditions considered overcrowded (European Commission).

This demonstrates that at least three distinct questions exist:

1. Who is the legal owner?

2. Who has security of tenure?

3. Who lives in adequate housing?

A good housing policy must address all three.

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Are Health, Education, and Housing Common Commodities?

In strict economic terms, health, education, and housing are not necessarily "pure public goods." A pure public good, such as national defense, is characterized by the difficulty of excluding anyone from its use and the fact that one person's consumption does not significantly reduce another's.

A house, a medical consultation, or a school desk can be individualized and commercialized.

However, health, education, and housing are frequently considered social goods, fundamental rights, or merit goods, because access to them produces effects that extend beyond the individual.

A population with secure housing tends to exhibit:

• Better health

• Greater family stability

• Better school performance

• Lower vulnerability to violence

• Greater community participation

• Greater long-term planning capacity

For this reason, even in capitalist economies, these sectors are rarely left entirely to the market.

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The True Contrast

The fundamental contrast is not simply between countries that accept or reject private property.

It lies between two modes of access to property.

In the first, which can be called mercantile acquisition, an individual must buy a house at market-determined prices using income, savings, and credit.

In the second, which we can call the distributive formation of property, the state, a cooperative, or a social institution first builds, finances, or controls the housing and then transfers its possession or ownership to the occupant.

Former socialist countries produced high homeownership rates because, during the transition, they converted massive public assets into millions of family-owned properties.

Meanwhile, some liberal economies intensely protect property but do not guarantee that every family can acquire one.

We can summarize the paradox as follows:

Liberal capitalism broadly guarantees the right to buy property, but does not necessarily distribute the means to acquire it. The socialist legacy restricted the real estate market for a period, but subsequently transferred millions of homes to their occupants, creating societies with a vast number of small property owners.

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What Would a More Balanced Model Look Like?

It is not necessary to choose between the complete state-control of housing and its full transformation into a financial commodity.

A balanced system could combine:

• Broad construction of social housing

• Housing cooperatives

• Long-term public or community renting

• Protection against arbitrary evictions

• Accessible financing for first-time homebuyers

• Progressive taxation on vacant properties and multiple holdings

• Limits on real estate speculation

• Programs for the gradual transfer of ownership to residents

• Permanent funds for building maintenance and renovation

• Preservation of a regulated private market

Homeownership can be a powerful form of security, autonomy, and intergenerational wealth transmission. But it should not be the only legitimate form of residential stability.

A family living in a rented home with a protected contract, affordable rent, and guaranteed tenure may have more security than one that formally owns a deteriorated, indebted residence with no resources for maintenance.

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Conclusion

Historical experience shows that the market is not the only path to forming private property.

Paradoxically, some of the largest processes of spreading homeownership occurred when socialist or post-socialist states transferred public properties to their occupants.

This reveals an essential difference between defending private property as an abstract principle and building a society in which property is broadly distributed.

An economy can be highly liberal and concentrate real estate. Another can feature strong state intervention and produce millions of small property owners.

The most important question, therefore, is not merely whether property is public or private. We must ask:

Who manages to live securely? Who can remain in their community? Who accumulates the properties? Who bears the maintenance costs? And how many families have effective control over the place where they live?

The quality of a housing system should not be measured solely by the freedom to buy and sell. It must be evaluated by its ability to ensure that no one is deprived of dignified housing and that real estate wealth does not progressively concentrate in the hands of a few.