What is a Solar Furnace?

The solar furnace is a pool of curved mirrors and mirrored surfaces that capture the sun rays and reflect them along with a single point where the energy gets focused. This focused energy can go up to 4000 degrees Celsius with some furnaces.

The energy or heat harnessed by the solar furnace can be utilized in several forms – to create electricity, melt metals, create fuel, or cook food.

In this article, let us explore the working technique of the solar furnace along with the uses, advantages, and disadvantages.

How does a solar furnace work?

The solar furnace has a concentration component that works in the same principle as a lit glass.

If you take two mirrors and point them at the focus, the intensity of solar power at the point of focus will increase by three times the total energy. The focus point takes the heat from the sunlight and considers the heat from two mirrors. If you can create threefold power with two mirrors, imagine if you place ten mirrors, and you might get those levels of heat that can be used to cook food.

Using the same technique, the solar furnaces use the heliostats to reflect the sun rays to a set of parabolic mirrors. These mirrors, in turn, help in focusing the sun’s rays on a furnace at the top of the tower.

The temperature at the furnace is usually high, raging at 800 degrees Celsius. The molten salt is put into the furnace to increase the temperature from 300 to 600 degrees Celsius. The hot molten salt is then stored in the storage tank in the furnace.

When the hot molten salt leaves the storage tank, it passes through the steam generator. The molten salt is mixed with water in the steam generator until it turns to steam.

Once the steam is generated, it is sent to the steam turbine, and the cold molten salt is returned to the storage tank.

As the steam enters the steam turbine, it causes the turbine to rotate. The steam turbine is connected to a gearbox, generating electricity. The condenser in the turbine condenses the steam, and the resultant steam is sent back to the steam generator and is again converted back to steam.

The electricity generated from the generator is then distributed to the electronic transformer, and the voltage is increased. The electricity is then transmitted through an open-air switchyard into the national grid.

Increasing the voltage reduces the loss when power is distributed to the national grid.

The Modular cooling towers also help cool down the steam and condensate them. Coldwater is sent to the condenser and heated in the steam, and the steam then changes its state and condenses.

What are the uses of the solar furnace?

Solar energy is focused on a pot-sized area and can induce a temperature of 4000 degrees Celsius. However, the temperature-induced depends on the process installed.

For example,

  • 1000 degrees Celsius to produce hot air for the next generation of solar powers using metal receivers
  • 1400 degrees Celsius to produce hydrogen by using the broken methane molecules.

The solar furnaces could be used in the space for generating energy for industrial uses. Though its dependence on solar energy is a limiting factor, it could be combined with the thermal energy storage systems to produce energy during cold and cloudy days.

There are also some small-scale uses for solar furnaces. In these small scall furnaces, the heat produced at the focal point is not so high. E.g., They can be used to power small engines or solar cookers.

The general uses of solar furnaces include,

The solar furnace can also produce aerospace products, defense products, and electronic products. They can also be used to destroy toxic waste. The High flux solar furnaces could easily replace the laser furnaces and furnaces running on fossil fuels. Its usage can also be extended to metallurgical industries.

What is the history of the solar furnace?

Professor Felix Trombe was the first to introduce the solar furnace to the world in 1949 at Mont Louis.

It is believed that Archimedes used some polished shields to focus the sunlight and concentrate them into a single path while invading the Roman fleet and repelling them from Syracuse.

In an experiment conducted by Lavoisier Circa 1770, combustion was created while focusing sunlight over the flammable material using lenses.

In 1861, Mouchout developed a steam engine exclusively powered by the sun.

In 1993, the industrialists started using solar furnaces for industrial and manufactured products such as ceramics, bronze, and aluminum products.    

What are the different types of solar furnaces?

There are two types of solar furnaces available –

  •  Direct Solar Furnace
  • Heliostat solar furnace

What are the advantages of solar furnaces?

  • Produces clean energy and can be used in places where pollution must be avoided
  • Lower cost
  • Reduces the process of burning out the fossil fuels
  • Reduces the need for cutting down the forest for firewood

What are the limitations of the solar furnace?

  • The solar furnace has existed for so many years, but it has never been fully explored or used widely.
  • Larger solar concentrators are very expensive
  • They occupy larger space

Application of solar furnaces

  • It can be used in cooking or heating of water in Domestic uses
  • In agricultural use, it can be used to dry farm produce and incubate chicken.
  • For industrial purposes, it can be used to recycle waste and welding machine parts.

Impact of Solar Furnace

Environmental Impact

  • Prevention of desert encroachment
  • Decrease in overdependence of fossil fuel
  • Global warming

Economic Impact

  • Recycling of waste
  • Recycling of metal scrap

Take Away

The solar furnace has not yet been fully explored or used widespread for commercial purposes. It is not clear if the solar furnaces will ever be used on any scale due to the limitations placed on their usage.

However, with R&D and technology developing every day with innovative people around, breakthroughs could lower costs and increase usage.