limitations of RE Sources 3.8.20 (1).pptx

renewable energy system

1. Limitations Of Renewable Energy sources Presented By S.Dhanalakshmi AP/EEE Christ the King Engineering College

2. Limitations of Renewable Energy Sources Many people still think that it will not be long before renewable energy such as solar and wind becomes outright cheaper than fossil fuels, thereby leading to a rapid expansion of the thin orange slither in the graph  below . This is an ideologically very attractive notion, but, as discussed in this article, it is questionable whether this is in fact physically possible. In other words, renewables need to overcome the following two challenges in order to displace fossil fuels in a fair market: Solar panels and wind turbines need to become cheaper than raw fossil fuels. This is the challenge posed by the diffuse nature of renewables. Storage solutions need to become cheaper than fossil fuel refineries (e.g. power plants). This is the challenge posed by the intermittent nature of renewables.

3. Point number 1 is the way in which we procure our energy (mining/drilling fossil fuels or deploying solar panels and wind turbines) and point number 2 is the way in which we make this energy useful to society at higher levels of penetration (refining fossil fuels to electricity or smoothing out the intermittent surges of renewable energy). Without point number 1, point number 2 cannot exist and without point number 2, the energy procured in point number 1 cannot sustain a complex society such as ours. Thus, if renewables are to challenge fossil fuels in an open market, technology must advance to the point where renewables can compete under both these points.

4. The reason behind this is called the second law of thermodynamics which states that energy must flow from a concentrated form to a more diffuse form in order to do work. Our entire society was built on the work performed through transforming concentrated fossil energy to diffuse heat and, in order to compete, renewable energy technologies also need to deliver such concentrated energy. Now there is no question that renewable energy can be sufficiently concentrated by solar panels and wind turbines. The only question is whether this can be done more cost effectively than simply digging already concentrated fossil fuels out of the ground. This challenge is two-fold. Firstly, energy does not like to be concentrated, hence the fact that the average commercially available solar panel is only about 13% efficient. And secondly, because the energy source is so diffuse, vast areas need to be covered in order to harvest this diffuse energy.

5. As a result of this challenge, it was  previously calculated  that the solar panel price needs to fall to about $0.31/W installed in order to compete with coal at $100/ton. It is therefore clear that installed solar prices still need to fall about one order of magnitude before we can see a sustained market driven displacement of coal by PV. Is this possible? Well, the most optimistic projection in the  OpenEI database  sees solar PV levelling off at about $1.44/W installed which is more than quadruple the required level. Perhaps we will be pleasantly surprised by some technological miracle in the medium-term future, but achieving the required prices with current PV technology will unfortunately be completely impossible.

6. The intermittent nature of renewables If intermittent renewables like solar and wind are ever to contribute a sizable portion of our global energy mix, a large amount of additional infrastructure will need to be deployed in order to counter the large fluctuations in output varying over timescales ranging from seconds to years. On a countrywide basis, the output varied over more than two orders of magnitude from a minimum of 0.115 GW to a maximum of 24 GW. It is clear that a large amount of extra infrastructure will be needed in order to smooth out this erratic output to something that better resembles the demand profile. Solar PV is of course even worse because it generates no power whatsoever for the majority of the time and delivers most of its energy in the few hours around noon.

7. Again, there can be no doubt that we have a wide range of technically proven solutions to this problem. When just looking at the area of energy storage there are many proven ways to store energy in chemical, kinetic and various potential forms. But again, the challenge is to deploy these solutions at a lower cost than that involved in the refinement of fossil fuels. A coal power plant is the most expensive kind of fossil fuel refinery. For example, a standard coal-fired power plant must sell electricity for about $0.06/kWh, but coal at $100/ton costs only $0.015/kWh. The remaining $0.045/kWh represents the price of refining coal to electricity and arises primarily from the low efficiency and high capital costs of coal plants.

8. So, how does energy storage compare? Well, a  recent test  of lead acid and Li-ion batteries found that these technologies could store energy for about $0.34 and $0.40 per kWh over their respective lifetimes. Hence, we again have to conclude that the most ideal renewable energy storage solution is still about one order of magnitude away from challenging fossil fuels on a level playing field. The Li-ion battery throughput cost of $0.40/kWh mentioned above was calculated for an initial cost of $600 per kWh of capacity. Most optimistic projections for Li-ion battery costs give longer-term prices at about $200 per kWh of capacity. At these prices, battery storage would be about triple the price of refining coal to electricity. Again, we need a technological miracle.

9. So, these are the facts. In order for intermittent renewable energy sources such as solar PV to effectively compete with fossil fuels like coal, both the price of installed solar panels and the price of battery storage will need to reduce by a full order of magnitude. In addition, optimistic long-term projections state that both solar panels and battery storage will reach technological maturity at roughly triple the cost of their fossil fuel counterpart Does this mean that it is fundamentally impossible for renewable energy to trump fossil fuels? Well, I would stop short of saying that, but, from this analysis, it appears unlikely that we will see a large scale market driven displacement of fossil fuels by renewable energy in the first half of this century.

10. CHALLENGES IN INCREASING RENEWABLES PENETRATION In addition to effects on generation and transmission, characteristics of renewable energy converters disrupt the way conventional electricity markets function. Market structures need to evolve to integrate renewable power properly.

11. HEAT AND TRANSPORT Energy consumption for heat and transport is a significant proportion of overall energy use in Europe. However, these are both sectors that have traditionally been heavily reliant on fossil fuels – for transport, through the use of petrol and diesel-fuelled cars; and for heating, through the use of oil and natural gas boilers in buildings. To decarbonise transport, we either need to incorporate biofuels, such as biodiesel, or switch to hybrid, electric or hydrogen cars. For heating, particularly in urban areas, the main approaches are through district heating or electrification of heat, or a combination of the two.

12. SOCIAL, POLITICAL AND ECONOMIC IMPLICATIONS On a national level, renewable energy may create new jobs in the industry and support moves towards a long-term sustainable development plan with lower risks associated with fuel import volatility, carbon prices and political tensions. This is particularly true where countries are highly dependent on fuel imports. The trade in electricity between countries is less prone to political tension than trade involving oil and gas. Naturally, some countries have more energy resources than others, but differences in electricity resources are smaller than those relating to fossil fuel reserves. Climate change is likely to affect future migration patterns. The latest report described the African continent as the one that will be most affected by climate change. As a consequence, Europe is likely to see increasing amounts of climate refugees. This may be subject to change as weather trends become increasingly less predictable and more severe and the number of “climate change refugees” increases.

13. Now, renewable power uptake is increasing the electricity prices and requires government support. However, in the long term, as technology matures, the costs of running an entire energy system on renewable energy will be lower and subsidies on fossil fuels are likely to fall away. CONCLUSIONS AND RECOMMENDATIONS One of the biggest challenges in the energy sector is matching the timings between generation and consumption of energy. On a “good” energy day, the sun blazes and the wind howls and fills our electricity grid with cheap, renewable energy. On a “bad” energy day, the skies are grey and the wind is still and we rely on backup from hydro or conventional generation. On good days we should also be furiously energetic and use as much energy as we can – and on bad days we should turn to quieter pursuits.

14. Digitalisation, energy storage and demand response are the keys to helping future energy systems maintain balance as we move from separate energy consumption. The generation of energy for heat, electricity and transport is interconnected through storage, monitored through smart meters, and changed through voluntary shifting of demand.

15. All over the world initiatives are being taken to minimise carbon emissions and the impacts of climate change. The increase of renewable energy is key to achieving a climate neutral, sustainable future and it’s a solution that is already being implemented in many different countries. The limits to renewables are not technical, or financial, or regulatory – they are the ones we set for ourselves and for each other.