Beyond Solar Panels: 6 Types of Solar Power Plants
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These are what come to mind when most people think of “solar power”—rows of flat solar panels mounted on top of a building or strewn along the side of a highway. Photovoltaic solar panels work thanks to a principal known as the photoelectric effect, in which certain materials exhibit a property of absorbing light photons and releasing electrons. By capturing these electrons an electrical current can be created.
Photovoltaic technology has come a long way since its discovery in 1839 by French physicist, Alexander Edmond Becquerel. It was over 100 years later, in 1941, that the first practical silicon monocrystalline PV solar cell was developed, and since then advancements in materials and production have led to thinner and more durable designs with widespread commercial use.
Now, giant photovoltaic farms—capable of producing hundreds of megawatts of electricity—are being developed by top companies like First Solar, SunPower, Sharp, Q-Cells, Suntech, and Yingli.
But photovoltaic solar panels aren’t the only type of solar power plant out there, and more exotic power plants are using the power of the sun in some very different ways.
Imagine rows of reflective troughs—like curved mirrors—reflecting the sun’s light and concentrating it on thin tubes of liquid (usually oil) that run the length of the troughs. The liquid is heated by the concentration of the sun’s rays to 400° C and carried via tube to a power station where it boils water to create steam and run power-generating turbines. The troughs are mounted on mechanized tracking units that follow the sun’s movement to increase efficiency.
This is the concept behind the parabolic trough solar power plant, and in just the last few years several of these power plants have popped up all over the world, capable of producing hundreds of megawatts of electricity. The added advantage of storing the sun’s rays as heat allows these power plants to continue to operate into the night and during intermittent cloud cover by regulating the heat transfer fluid. Companies leading the way with solar troughs include Spain’s Abengoa and Acciona.
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Solar dishes—like giant mirrored satellite dishes—operate in a similar fashion to parabolic troughs, but focus light onto a central point mounted above the dish. Some systems use the concentrated solar heat to create steam; however, a more efficient system has been created by Stirling Energy Systems Inc. and has already been employed in the Maricopa solar plant in the sunny deserts of Arizona in the United States.
The Stirling “SunCatcher” is a solar dish that tracks the sun and focuses light on a central power converter unit. The unit is filled with hydrogen gas, and when heated by the concentrated sunrays, the gas pressurizes to turn cylinders in a power-generating engine. It operates much like a combustion engine minus the combustion, making it relatively quiet, and it is hailed as one of the most efficient and cost-effective solar systems on the market.
This design functions in much the same way as parabolic troughs, but instead of using expensive curved mirrors, Fresnel reflector solar power plants use several rows of flat mirrors all angled to focus on the absorption tube. This can be a cost-effective alternative to parabolic troughs, since flat mirrors are much cheaper to produce than curved ones. Companies streamlining production of Fresnal reflector systems include Elianto, AREVA and Novatec Biosol.
Solar Power Tower
Now imagine something like a giant solar dish—with thousands of mirrors (called ‘heliostats’) positioned on the ground to reflect sunlight upward to the top of a giant central tower. The top of this tower houses a bulbous metal chamber of molten salt (or water in some models) that absorbs and stores the concentrated heat from the reflected sunrays in order to boil water and use steam to run power-generating turbines. Companies like SolarReserve, eSolar, Abengoa, BrightSource Energy, and SENER have been pioneering the solar power tower market, with several plants operating in the Spain and one in the U.S.
This design heats the air in a giant enclosed canopy that surrounds a gargantuan central tower. The tower acts as an escape chimney for the hot air created in the canopy. Since heat rises, the hot air will push its way out of the canopy and up through the tube-like central tower. Turbines are placed within the tower to harness the energy of the updraft and generate electricity. While these towers and their canopies need to be built on a massive scale—think larger than most New York City skyscrapers—it is important that they serve a dual purpose, and since the canopy that heats the air acts as a gigantic greenhouse, hundreds of acres of cash crops can be planted within, increasing the power plant’s overall utility. Australian company EnviroMission Limited is on track to develop the first large-scale solar tower project in the deserts of Arizona in the United States.
Carbon dioxide removal revenues worth £2bn a year by 2030
Carbon dioxide removal revenues could reach £2bn a year by 2030 in the UK with costs per megatonne totalling up to £400 million, according to the National Infrastructure Commission.
Engineered greenhouse gas removals will become "a major new infrastructure sector" in the coming decades - although costs are uncertain given removal technologies are in their infancy - and revenues could match that of the UK’s water sector by 2050. The Commission’s analysis suggests engineered removals technologies need to have capacity to remove five to ten megatonnes of carbon dioxide no later than 2030, and between 40 and 100 megatonnes by 2050.
The Commission states technologies fit into two categories: extracting carbon dioxide directly out of the air; and bioenergy with carbon capture technology – processing biomass to recapture carbon dioxide absorbed as the fuel grew. In both cases, the captured CO2 is then stored permanently out of the atmosphere, typically under the seabed.
The report sets out how the engineered removal and storage of carbon dioxide offers the most realistic way to mitigate the final slice of emissions expected to remain by the 2040s from sources that don’t currently have a decarbonisation solution, like aviation and agriculture.
It stresses that the potential of these technologies is “not an excuse to delay necessary action elsewhere” and cannot replace efforts to reduce emissions from sectors like road transport or power, where removals would be a more expensive alternative.
The critical role these technologies will play in meeting climate targets means government must rapidly kick start the sector so that it becomes viable by the 2030s, according to the report, which was commissioned by government in November 2020.
Early movement by the UK to develop the expertise and capacity in greenhouse gas removal technologies could create a comparative advantage, with the prospect of other countries needing to procure the knowledge and skills the UK develops.
The Commission recommends that government should support the development of this new sector in the short term with policies that drive delivery of these technologies and create demand through obligations on polluting industries, which will over time enable a competitive market to develop. Robust independent regulation must also be put in place from the start to help build public and investor confidence.
While the burden of these costs could be shared by different parts of industries required to pay for removals or in part shared with government, the report acknowledges that, over the longer term, the aim should be to have polluting sectors pay for removals they need to reach carbon targets.
Polluting industries are likely to pass a proportion of the costs onto consumers. While those with bigger household expenditures will pay more than those on lower incomes, the report underlines that government will need to identify ways of protecting vulnerable consumers and to decide where in relevant industry supply chains the costs should fall.
Chair of the National Infrastructure Commission, Sir John Armitt, said taking steps to clean our air is something we’re going to have to get used to, just as we already manage our wastewater and household refuse.
"While engineered removals will not be everyone’s favourite device in the toolkit, they are there for the hardest jobs. And in the overall project of mitigating our impact on the planet for the sake of generations to come, we need every tool we can find," he said.
“But to get close to having the sector operating where and when we need it to, the government needs to get ahead of the game now. The adaptive approach to market building we recommend will create the best environment for emerging technologies to develop quickly and show their worth, avoiding the need for government to pick winners. We know from the dramatic fall in the cost of renewables that this approach works and we must apply the lessons learned to this novel, but necessary, technology.”
The Intergovernmental Panel on Climate Change and International Energy Agency estimate a global capacity for engineered removals of 2,000 to 16,000 megatonnes of carbon dioxide each year by 2050 will be needed in order to meet global reduction targets.
Yesterday Summit Carbon Solutions received "a strategic investment" from John Deere to advance a major CCUS project (click here). The project will accelerate decarbonisation efforts across the agriculture industry by enabling the production of low carbon ethanol, resulting in the production of more sustainable food, feed, and fuel. Summit Carbon Solutions has partnered with 31 biorefineries across the Midwest United States to capture and permanently sequester their CO2 emissions.
Cory Reed, President, Agriculture & Turf Division of John Deere, said: "Carbon neutral ethanol would have a positive impact on the environment and bolster the long-term sustainability of the agriculture industry. The work Summit Carbon Solutions is doing will be critical in delivering on these goals."
McKinsey highlights a number of CCUS methods which can drive CO2 to net zero:
- Today’s leader: Enhanced oil recovery Among CO2 uses by industry, enhanced oil recovery leads the field. It accounts for around 90 percent of all CO2 usage today
- Cementing in CO2 for the ages New processes could lock up CO2 permanently in concrete, “storing” CO2 in buildings, sidewalks, or anywhere else concrete is used
- Carbon neutral fuel for jets Technically, CO2 could be used to create virtually any type of fuel. Through a chemical reaction, CO2 captured from industry can be combined with hydrogen to create synthetic gasoline, jet fuel, and diesel
- Capturing CO2 from ambient air - anywhere Direct air capture (DAC) could push CO2 emissions into negative territory in a big way
- The biomass-energy cycle: CO2 neutral or even negative Bioenergy with carbon capture and storage relies on nature to remove CO2 from the atmosphere for use elsewhere