ENERGY HOLY GRAIL OR... ? (THERMAL) SOLAR ENERGY

Generating and using energy in such a way that it doesn't impact the environment. This has been pursued for many years, but this green future vision now seems more realistic than ever. While a number of sustainable forms of energy have proven successful and are being scaled up in capacity, other forms of energy are still in their infancy. This is the time to join forces, to apply and combine knowledge and expertise from different sectors. Together we are responsible and together we can make a difference. In this edition we talk about (thermal) solar energy.

In 2019, the global solar energy capacity was estimated to increase by 118 GW11. This appears to be the largest increase ever! In ten years, solar energy has grown 26 times. By comparison: wind energy has 'only' quadrupled. The report 'Global Trends in Renewable Energy Investment 2020' (by Frankfurt School - UNEP Collaborating Centre for Climate & Sustainable Energy Finance) describes that solar energy has added more new capacity globally than any other energy generation source in the past decade, 625 GW.

Solar energy and solar heat

When we are talking about the sun in relation to renewable energy, it quickly becomes about solar energy, but there is also solar heat (solar thermal energy). At least as valuable! But less known, although that seems to be changing... Arno Tromp will explain more about that. He is importer of Solvis, specialist in terms of solar thermal systems and solar collectors.

What exactly is solar energy?

Solar energy is a way of generating energy directly from the sun's radiation using technology. This can be done in a number of ways. The most common and well-known form of generating solar energy is the use of solar panels with photovoltaic cells (PV cells). This allows sunlight to be converted directly into electricity. Solar heat is created by converting sunlight into heat: thermal solar energy. Solar collectors combined with solar boilers are used for this purpose. There are also solar towers that can be used to produce solar heat on a large scale. Such as 'Gemasolar', a 19.9

MWe thermal solar power plant in Spain, covering 195 hectares.

Why choose (thermal) solar energy?

Generating solar energy offers many advantages. Households, for example, can save considerably on their annual energy costs if they have a number of solar panels on their roof, and that also applies to business users. Of course they also contribute to a greener world and they recoup their investment within a reasonable period. In addition, the sun provides a lot of energy, even on cloudy days you can generate energy with solar panels. This also applies to solar collectors, which generate heat all year round. In fact, solar collectors provide the highest energy yield per m2 surface area. 2

"There is particular discussion of panels, not collectors. In practice, people choose solar panels more easily. They are easier for suppliers to sell and easier to subsidize. But in the Netherlands the need for heat is much greater than the electricity we use. In fact, you need both collectors and panels. There are combination systems, which we are now exploring. It doesn’t work ideally yet. Solvis, for example, has the PVT combination panel. This panel has the disadvantages of collectors and panels, but unfortunately not the advantages of both. It is now in the testing and development phase and is very promising," says Arno Tromp.

The disadvantages and challenges

Solar panels are popular, solar collectors promising. But there are drawbacks, or rather challenges. Panels and collectors generate energy and heat even when you don't necessarily need it. Arno Tromp: "The tricky thing is that you cannot yet store solar energy for the long term. Since everything concerning sustainable energy depends on accommodation, you need something in which you can store it for a longer period of time. There are bunkers, in which solar heat constitutes the source for a water pump in winter. In this way, the remaining solar heat in summer can be used in winter. In Germany, Switzerland and Italy you can find several such bunkers. In the Netherlands there is one. The problem is that it is very expensive, so I don't expect this to be the solution for storage. Besides, this is purely about storing heat, not solar energy."

Combining renewable energy forms

On different fronts, people are working hard to find the best sustainable forms for generating energy. For example, there is a great deal of discussion about the possibilities of hydrogen, and hydropower provides almost all of the sustainable energy in one country, while in another it is barely significant. In other words: there is no one single solution. Arno Tromp agrees: "It is extremely important to really look at the demand. In practice, the approach is often wrong and advice is sought from the wrong organizations so that something is simply chosen from an available catalog. But that is not the way. It is important that you look at what can be improved and then at all possible sustainable solutions and the modular possibilities therein. Solvis is a specialist in solar, but that doesn't mean we only look at that. It is important to make a good connection, to look for the best solution for a specific situation. Sometimes that means a connection with a heat pump, sometimes with a fuel cell that generates electricity from hydrogen. But soil (geothermal) and air systems are also applicable when you're talking about thermal solar energy."

Who can use energy from the sun?

Solar panels and solar collectors offer a solution for both private and business customers. But there are still many opportunities - especially for thermal solar energy. Companies that need heat for their processes can benefit from thermal solar energy.2 From process industry to greenhouse horticulture, from livestock farming to the recreational sector, from healthcare institutions to car washes. "Solar thermal is still going to conquer the world," adds Arno Tromp. "There's no way around that! The trend seems to be set, now it has to happen. They are proven technologies, the numbers don't lie. They are great modular systems. At this point it's mainly about generating more awareness for this sustainable form of energy. Solar thermal must step out of the shadow of solar energy."

Many applications

The application of solar energy is diverse. As mentioned, solar provides homes, businesses and industry with power and heat. In addition to buildings, we also see more and more devices that run on solar energy, such as watches and smartphones. Swimming pools are heated thanks to collectors, in private homes in the backyard, but also at the large municipal swimming pools.

In addition, there are great initiatives that are continually expanding the applications of solar energy. The TU Delft Solar Boat Team, consisting of 21 students from eight different fields of study, design and produce a solar-powered boat in one year that is used for spectacular races.3 TU Delft students have been doing this for about 15 years. There are also more and more solar-powered cars and experiments with solar airplanes.

There are more and more possibilities for the application of (thermal) solar energy and thus this sustainable form of energy continues to develop. Particularly in thermal solar energy, we are going to make great strides worldwide in the coming years.

Sources:

1. Frankfurt School / FS-UNEP Collaborating Centre for Climate & Sustainable Energy Finance

2. Potentie grootschalige zonthermie sterk onderschat

3. TU Delft Solar Boat Team

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