How can solar energy replace fossil fuels

Wind turbines and solar photovoltaic PV cells convert solar energy flows into electricity, in a process much more efficient than burning biomass, the pre-industrial way of capturing solar energy. Costs for wind and solar PV have been dropping rapidly and they are now mainstream, cost-effective technologies.

Combining new renewables with these existing sources represents an opportunity to decarbonize — or eliminate CO 2 emissions from — the electricity sector. However, unlike fossil fuels, wind and solar can only generate electricity when the wind is blowing or the sun is shining. This is an engineering challenge, since the power grid operates in real time: Power is generated and consumed simultaneously, with generation varying to keep the system in balance.

Engineering challenges beget engineering solutions, and a number of solutions can help. Power storage technologies can save excess electricity to be used later. Hydroelectric dams can serve this function now, and declining costs will make batteries more economic for power storage on the grid. Storage solutions work well over a timeframe of hours — storing solar power to use in the evening, for example.

But longer-term storage poses a greater challenge. Perhaps excess electricity can be used to create hydrogen or other fuels that can be stored and used at a later time. Finally, fossil fuel generation often fills in the gaps in renewable generation today, especially natural gas generation, which can be efficiently ramped up and down to meet demand. Transforming solar energy flow into electricity is a clear place to start in creating a decarbonized energy system.

A simple formula is to decarbonize the electricity sector and electrify all the energy uses we can. Many important processes can be electrified — especially stationary uses, like in buildings and many industrial processes. To deal with climate change, this formula is the low-hanging fruit. The two parts of this formula must proceed together. A shiny new electric vehicle in the driveway signals your concern about the environment to your neighbors, but achieving its full potential benefit also requires a greener power system.

Achieving the full potential benefit of electric vehicles would require a grid that supplies all renewable or zero-carbon power, something that no area in the United States consistently achieves today.

Certain qualities of fossil fuels are difficult to replicate, such as their energy density and their ability to provide very high heat. To decarbonize processes that rely on these qualities, you need low-carbon fuels that mimic the qualities of fossil fuels.

The energy density of fossil fuels is particularly important in the transportation sector. A vehicle needs to carry its fuel around as it travels, so the weight and volume of that fuel are key. Electric vehicles are a much-touted solution for replacing oil, but they are not perfect for all uses.

Pound for pound, gasoline or diesel fuel contain about 40 times as much energy as a state-of-the-art battery. On the other hand, electric motors are much more efficient than internal combustion engines and electric vehicles are simpler mechanically, with many fewer moving parts. Industrial processes that need very high heat — such as the production of steel, cement, and glass — pose another challenge. These very high temperatures are hard to achieve without burning a fuel and are thus difficult to power with electricity.

For these processes, the world needs zero-carbon fuels that mimic the properties of fossil fuels — energy-dense fuels that can be burned. A number of options exist, but they each have pros and cons and generally need more work to be commercially and environmentally viable. Biofuels are a possibility, since the carbon released when the biofuel is burned is the same carbon taken up as the plant grew. However, the processing required to turn plants into usable fuels consumes energy, and this results in CO 2 emissions, meaning that biofuels are not zero-carbon unless the entire process runs on renewable or zero-carbon energy.

Biofuels also compete for arable land with food production and conservation uses, such as for recreation or fish and wildlife, which gets more challenging as biofuel production increases. Fuels made from crop waste or municipal waste can be better, in terms of land use and carbon emissions, but supply of these wastes is limited and the technology needs improvement to be cost-effective. Another pathway is to convert renewable electricity into a combustible fuel.

Hydrogen can be produced by using renewable electricity to split water atoms into their hydrogen and oxygen components. The hydrogen could then be burned as a zero-carbon fuel, similar to the way natural gas is used today. Electricity, CO 2 , and hydrogen could be also combined to produce liquid fuels to replace diesel and jet fuel.

However, when we split water atoms or create liquid fuels from scratch, the laws of thermodynamics are not in our favor. These processes use electricity to, in effect, run the combustion process backwards, and thus use large amounts of energy. Since these processes would use vast amounts of renewable power, they only make sense in applications where electricity cannot be used directly.

Carbon capture and storage or use is a final possibility for stationary applications like heavy industry. Fossil fuels would still be burned and create CO 2 , but it would be captured instead of released into the atmosphere.

Processes under development envision removing CO 2 from ambient air. In either case, the CO 2 would then be injected deep underground or used in an industrial process. The most common use for captured CO 2 today is in enhanced oil recovery, where pressurized CO 2 is injected into an oil reservoir to squeeze out more oil. The idea of capturing CO 2 and using it to produce more fossil fuel seems backwards — does that really reduce emissions overall?

But studies show that the captured CO 2 stays in the oil reservoir permanently when it is injected in this way. And if enough CO 2 is injected during oil production, it might make up for the combustion emissions of the produced oil, or even result in overall negative emissions. For more guidance, check out these 25 tips on green living at home. Conferences like the United Nations Framework Convention on Climate Change held in Paris are a good start, but there must be a unified followthrough that focuses on holistic efforts.

Rising temperatures affect everyone, so the solutions must have the same impact. For renewable energy to overtake fossil fuels as the way people power their homes and businesses, we will all have to work together at adoption, research, development, and implementation. We must take actionable steps to prepare our homes, businesses, energy grids, and economies for this change.

Is there a future where increased usage of sustainable energy can work in tandem with reduced fossil fuels? Absolutely — as many of the products we use to produce solar and wind power come from oil.

Thus, even if we keep oil, coal, and natural gas in the energy mix, we need to find ways to use less of them. We can also make inroads to rid ourselves of fossil fuels entirely if we have the collective will. It often starts with individuals making the right choices for their own lives and then sharing the impact of those choices with their friends, family, local businesses, and government representatives. Comparing Renewable Energy with Fossil Fuels With very few exceptions, most energy industry experts believe we should adopt clean energy resources.

Yet she maintains a positive outlook. The capacity to make this substantial change from a fossil-based to a renewables-based economy is going to be there. We just need to drive it forward. Ranked the No. Committed to hands-on and online, real-world learning, Purdue offers a transformative education to all. Committed to affordability and accessibility, Purdue has frozen tuition and most fees at levels, enabling more students than ever to graduate debt-free.

See how Purdue never stops in the persistent pursuit of the next giant leap at purdue. Media contact: Amy Patterson Neubert, , apatterson purdue.

Source: Maureen McCann, mmccann purdue. Around the world, grid operators are managing larger amounts of wind and solar every year. While most energy storage currently comes from pumped hydro storage facilities, the use of battery energy storage is growing rapidly, because of its increasingly cost competitiveness. If they are charged by renewable energy sources, they have no added GHG emissions.

Batteries can provide a variety of services to the grid, including smoothing the variability of wind and solar. Storage can provide the necessary back-up or standby power that the film implies must come from standby gas or coal-fired generators. Using batteries to replace fossil fuel backup will mean higher levels of wind and solar on the grid, less need for gas and coal and fewer emissions. More work is needed — and is underway — on long-duration storage options as part of the suite of tools needed for a reliable, affordable, low-carbon power system.

The useful lifespan of renewable facilities can exceed two decades. Wind turbines, for example, are estimated to last for about 20 years, and photovoltaic systems often remain operational from 25 to 40 years.

In some instances, as large wind turbines become more efficient and economic, equipment turnover has been accelerated. In these cases, smaller turbines have been replaced earlier than they might otherwise have been by larger, more efficient turbines, to substantially increase electricity production at existing sites. Furthermore, renewable energy facilities can typically be deployed more rapidly than fossil fuel plants.

While solar and onshore wind farms normally take less than two years to build, gas-fired power plants usually take as many as four years to become operational, and can also require construction of gas pipeline infrastructure. While all sources of electricity result in some GHG emissions over their lifetime, renewable energy sources have substantially fewer emissions than fossil fuel-fired power plants. Most of the lifecycle emissions from fossil generators occur from fuel combustion, but also come from raw materials extraction, construction, fuel processing, plant operation and decommissioning of facilities.

While the manufacture of solar panels requires substantial amounts of energy, studies have found that they offset the energy consumed in production within about two years of operation, depending on the module type. Both crystalline silicon and thin-film solar panels contain toxic materials such as lead, silver and cadmium; therefore, efforts need to be accelerated to address proper disposal practices and module recycling , such as is done in Europe and by First Solar in the U.

Electrification of passenger vehicles has quickened in recent years, with more than 1 million electric vehicles EVs now operating in the United States. Several studies suggest that number could grow to 20 million EVs by , with over 4 million EVs in California alone.

EVs offer substantial emissions benefits — and associated health benefits — because they are two to three times more efficient than conventional internal combustion vehicles and have no tailpipe emissions. However, they do release GHG emissions during the fuel production, vehicle manufacturing and vehicle use stage.

But, as we point out in a recent WRI report , new solutions are still needed to enable customers to charge their EVs with renewables more easily.