The started 2012 was proclaimed the «International year of sustainable energy for all». One of its objectives - to increase attention to the possibilities of renewable energy sources (RES), to activate their use. Much attention is paid to this field in Uzbekistan. On the progress and prospects in this direction - a conversation with the chairman of the Society of Physics of Uzbekistan, Doctor of Physical and Mathematical Sciences, Davron Matrasulov.

- At what level is the development of alternative energy today?

- First, let us define what we mean by this term. Alternative, as often called, is the energy, based on renewable sources - solar, wind, geothermal, thermoelectric, bio, hydro and hydrogen energy. However, this concept implies any form of energy different from the traditional and widely used. It is often said also about the green or low-carbon energy, «low-carbon society,» where the appropriate environmentally friendly sources are purposefully developed. Most of the RES meet these requirements. The most promising of them - wind and solar, although their effectiveness depends on the climate of a certain region. Biogas and biomass yield due to the limited natural resources.

Financial figures characterize the interest in alternative energy the best. Investing in this field grows. In particular, at the beginning of 2010 the global investment volume exceeded $ 200 billion. Among the developed countries the first place is occupied by Germany where RES provide over 20 % of energy production. The share of developing countries, including China, accounts for more than half of that amount. China over the past three or four years is the leader in terms of volume and rate of increase in investments. Over one third of funds is directed to the solar energy, but the share of the latter in the world commercial energy is less than one percent. A significant portion is the funding of scientific and practical studies, which are mainly aimed at increasing the effectiveness of technology. The same is the contribution of alternative energy, excluding hydro-electric plants, to the production of energy in Uzbekistan.

- What renewable sources are the most significant for us?

- In the short term - solar energy, biogas and small hydroelectric plants. It is profitable to build the latter in mountain and piedmont areas, and biogas can be used in any climatic conditions. But the more significant is the day star. The sun’s rays falling on the Earth’s surface during the day exceed in their energy the entire stock of hydrocarbon and uranium resources. The main advantages of our region are that the intensity of their flow is one of the maximum on the planet, the average annual number of sunny days – 300. And because this, efficiency of energy conversion of the star into electric energy here is the maximum. Along with this we can successfully develop solar thermal power - it will help heat the spaces and distil water, which is especially important for rural areas.

According to experts, the use of solar energy to generate 25-30 % of consumed electricity in the world today will allow to reduce annual emissions of carbon dioxide into the atmosphere by about 23 billion tons, and to reduce the harmful contribution of thermal power plants to climate change. The energy thus obtained can also be exported. So over the past two decades, the interest in solar energy has grown substantially everywhere. In 1985 its capacity was 21 megawatt, in 2008 - 2000 megawatts, and last year exceeded 17000 megawatt. According to optimistic forecasts, by the middle of this century, the volume of production reaches the named bar of 25 % of global production. To do this, the mass introduction of solar panels at the household level is required.

It is also important to increase the efficiency of conversion of star energy into electrical energy, that is, the efficiency ratio of solar cells. It is the task of science, and special hope is now placed on nanotechnology. Physicists are working on the creation of elements of the third generation on the basis of a new generation of materials - the so-called carbon nano-materials, with an efficiency factor above 50 %, whereas the current ones do not exceed 30. They, particularly graphene, have high resource-saving features that exceed the usual ones in tens and even hundreds of times, and allow to achieve maximum miniaturization of devices. In the next five or six years, these elements can radically change the situation in the field of RES, which also spur interest in solar energy in the world.

- And in the long run?

- The hydrogen energy can be in the forefront here and abroad. Hydrogen - one of the most popular on the planet, and environmentally friendly substances. But the technologically unsolved problem is its safe storage. Number of local scientists and physicists develop the ways to solve it at this moment. The optimum storage of hydrogen is considered to be in carbon nanostructures (nanotubes, graphene, etc.) and clathrate structures of water – nanoscale cavities formed by its molecules. The latter is the most safe and effective in terms of commercialization. Here the main challenge for science is to increase the gas capacity of such structures up to 150 liters of gas per liter of water.

The issue will allow to replace hydrocarbon fuel by hydrogen fuel, while significantly reducing atmosphere pollution. Therefore, developed countries are investing significant funds in the development of this area and the main sponsors of the studies are the largest automobile manufacturers.

Thermoelectricity can be a very significant method of energy production for the future. It is based on the occurrence of an electric current through the temperature difference in the respective materials. Until recently this type was considered unpromising because of the very low efficiency of thermoelectric devices. In the present ones the factor of merit is less than one. In order to make them commercially profitable, it is necessary to increase the rate in triple, and in this the scientists are helped by nanotechnology. The efficiency of thermoelectric devices have already been improved to the required level by creating a lowdimensional nano-materials based on carbon nanostructures, but so far only in laboratory conditions.

- The use of alternative energy innovation today is quite expensive. Distribution of solar energy is difficult due to high, especially for residential consumers, cost of solar batteries and a long payback period - more than 35 years. Under what conditions value in dispute may become more accessible for the mass adoption?

- The interest of the state and society is already there. It is required to conduct scientifically based study of the potential of alternative energy, as well as marketing research with participation of interested agencies, financial institutions and private entities to determine the priority consumers.

To solve the applied component of the issue the Uzbekistan has sufficient personnel base of physicists who are working successfully in advanced directions. We have experience in the design and optimization of technological processes for production of bulk crystals and silicon films using gas-phase and vacuum methods, as well as the creation of tools and methods for monitoring electrophysical characteristics of semiconductor materials and devices.

Local experts in solid state physics have developed a number of effective technologies for obtaining of technical silicon from silica compounds. It is the material used to produce pure silicon - the basis of solar cells and other semiconductor electronic devices. It is known that a number of countries-producers of silicon - USA, China, South Korea and others - have imposed a ban on its export. This means that it becomes the strategic raw materials along with materials such as uranium, plutonium, gold and platinum. And in Uzbekistan there are deposits of quartzite and gangue quartz with pre-estimated reserves of a few tens of millions of tons, as well as deposits of quartz sand.

Therefore, on December 12th of last year, the Cabinet of Ministers of Uzbekistan approved the investment project of organization of the first phase of production of industrial silicon at JV JSC «UzKor Silicon» in Navoi region. It will undoubtedly allow to create the country’s own high-tech production of solar cells and panels at affordable prices. So the process of implementing of renewable energy sources is gaining momentum. And the more actively they will be used, the more innovative will be the Uzbekistan economy, the more resources we will save up for ourselves and future generations.