Union of Concerned Scientists: The Benefits of Renewable Energy Use

This page explores the many positive impacts of clean energy, including the benefits of wind, solar, geothermal, hydroelectric, and biomass. For more information on their negative impacts—including effective solutions to avoid, minimize, or mitigate—see our page on The Environmental Impacts of Renewable Energy Technologies.

Less global warming

Human activity is overloading our atmosphere with carbon dioxide and other global warming emissions. These gases act like a blanket, trapping heat. The result is a web of significant and harmful impacts, from stronger, more frequent storms, to drought, sea level rise, and extinction.

In the United States, about 29 percent of global warming emissions come from our electricity sector. Most of those emissions come from fossil fuels like coal and natural gas [1, 2].

What is CO2e?

Carbon dioxide (CO2) is the most prevalent greenhouse gas, but other air pollutants—such as methane—also cause global warming. Different energy sources produce different amounts of these pollutants. To make comparisons easier, we use a carbon dioxide equivalent, or CO2e—the amount of carbon dioxide required to produce an equivalent amount of warming.

In contrast, most renewable energy sources produce little to no global warming emissions. Even when including “life cycle” emissions of clean energy (ie, the emissions from each stage of a technology’s life—manufacturing, installation, operation, decommissioning), the global warming emissions associated with renewable energy are minimal [3].

The comparison becomes clear when you look at the numbers. Burning natural gas for electricity releases between 0.6 and 2 pounds of carbon dioxide equivalent per kilowatt-hour (CO2E/kWh); coal emits between 1.4 and 3.6 pounds of CO2E/kWh. Wind, on the other hand, is responsible for only 0.02 to 0.04 pounds of CO2E/kWh on a life-cycle basis; solar 0.07 to 0.2; geothermal 0.1 to 0.2; and hydroelectric between 0.1 and 0.5.

Renewable electricity generation from biomass can have a wide range of global warming emissions depending on the resource and whether or not it is sustainably sourced and harvested.

Different sources of energy produce different amounts of heat-trapping gases. As shown in this chart, renewable energies tend to have much lower emissions than other sources, such as natural gas or coal.

Increasing the supply of renewable energy would allow us to replace carbon-intensive energy sources and significantly reduce US global warming emissions.

For example, a 2009 UCS analysis found that a 25 percent by 2025 national renewable electricity standard would lower power plant CO2 emissions 277 million metric tons annually by 2025—the equivalent of the annual output from 70 typical (600 MW) new coal plants [4].

In addition, a ground-breaking study by the US Department of Energy’s National Renewable Energy Laboratory (NREL) explored the feasibility of generating 80 percent of the country’s electricity from renewable sources by 2050. They found that renewable energy could help reduce the electricity sector’s emissions by approximately 81 percent [5].

Improved public health

The air and water pollution emitted by coal and natural gas plants is linked with breathing problems, neurological damage, heart attacks, cancer, premature death, and a host of other serious problems. The pollution affects everyone: one Harvard University study estimated the life cycle costs and public health effects of coal to be an estimated $74.6 billion every year. That’s equivalent to 4.36 cents per kilowatt-hour of electricity produced—about one-third of the average electricity rate for a typical US home [6].

Most of these negative health impacts come from air and water pollution that clean energy technologies simply don’t produce. Wind, solar, and hydroelectric systems generate electricity with no associated air pollution emissions. Geothermal and biomass  systems emit some air pollutants, though total air emissions are generally much lower than those of coal- and natural gas-fired power plants.

In addition, wind and solar energy require essentially no water to operate and thus do not pollute water resources or strain supplies by competing with agriculture, drinking water, or other important water needs. In contrast, fossil fuels can have a significant impact on water resources: both coal mining and natural gas drilling can pollute sources of drinking water, and all thermal power plants, including those powered by coal, gas, and oil, withdraw and consume water for cooling. 

Biomass and geothermal power plants, like coal- and natural gas-fired power plants, may require water for cooling. Hydroelectric power plants can disrupt river ecosystems both upstream and downstream from the dam. However, NREL’s 80-percent-by-2050 renewable energy study, which included biomass and geothermal, found that total water consumption and withdrawal would decrease significantly in a future with high renewables [7].

Inexhaustible energy

Strong winds, sunny skies, abundant plant matter, heat from the earth, and fast-moving water can each provide a vast and constantly replenished supply of energy. A relatively small fraction of US electricity currently comes from these sources, but that could change: studies have repeatedly shown that renewable energy can provide a significant share of future electricity needs, even after accounting for potential constraints [9].

In fact, a major government-sponsored study found that clean energy could contribute somewhere between three and 80 times its 2013 levels, depending on assumptions [8]. And the previously mentioned NREL study found that renewable energy could comfortably provide up to 80 percent of US electricity by 2050.

Jobs and other economic benefits

Two energy workers on a roof

Two energy workers installing solar panels.

Compared with fossil fuel technologies, which are typically mechanized and capital intensive, the renewable energy industry is more labor intensive. Solar panels need humans to install them; wind farms need technicians for maintenance. This means that, on average, more jobs are created for each unit of electricity generated from renewable sources than from fossil fuels.

Renewable energy already supports thousands of jobs in the United States. In 2016, the wind energy industry directly employed over 100,000 full-time-equivalent employees in a variety of capacities, including manufacturing, project development, construction and turbine installation, operations and maintenance, transportation and logistics, and financial, legal, and consulting services [10]. More than 500 factories in the United States manufacture parts for wind turbines, and wind power project installations in 2016 alone represented $13.0 billion in investments [11].

Other renewable energy technologies employ even more workers. In 2016, the solar industry employed more than 260,000 people, including jobs in solar installation, manufacturing, and sales, a 25% increase over 2015 [12]. The hydroelectric power industry employed approximately 66,000 people in 2017 [13]; the geothermal industry employed 5,800 people [14].

Increased support for renewable energy could create even more jobs. The 2009 Union of Concerned Scientists study of a 25-percent-by-2025 renewable energy standard found that such a policy would create more than three times as many jobs (more than 200,000) as producing an equivalent amount of electricity from fossil fuels [15]. 

In contrast, the entire coal industry employed 160,000 people in 2016 [26].

In addition to the jobs directly created in the renewable energy industry, growth in clean energy can create positive economic “ripple” effects. For example, industries in the renewable energy supply chain will benefit, and unrelated local businesses will benefit from increased household and business incomes [16].

Listen to energy expert Paula Garcia talk about renewable energy progress in the US on the Got Science? Podcast:

In English:

En español:

Local governments also benefit from clean energy, most often in the form of property and income taxes and other payments from renewable energy project owners. Owners of the land on which wind projects are built often receive lease payments ranging from $3,000 to $6,000 per megawatt of installed capacity, as well as payments for power line easements and road rights-of-way. They may also earn royalties based on the project’s annual revenues. Farmers and rural landowners can generate new sources of supplemental income by producing feedstocks for biomass power facilities. UCS analysis found that a 25-by-2025 national renewable electricity standard would stimulate $263.4 billion in new capital investment for renewable energy technologies, $13.5 billion in new landowner income from biomass production and/or wind land lease payments, and $11.5 billion in new property tax revenue for local communities [17].

Stable energy prices

Renewable energy is providing affordable electricity across the country right now, and can help stabilize energy prices in the future.

Although renewable facilities require upfront investments to build, they can then operate at very low cost (for most clean energy technologies, the “fuel” is free). As a result, renewable energy prices can be very stable over time.

Moreover, the costs of renewable energy technologies have declined steadily, and are projected to drop even more. For example, the average price to install solar dropped more than 70 percent between 2010 and 2017 [20]. The cost of generating electricity from wind dropped 66 percent between 2009 and 2016 [21]. Costs will likely decline even further as markets mature and companies increasingly take advantage of economies of scale.

In contrast, fossil fuel prices can vary dramatically and are prone to substantial price swings. For example, there was a rapid increase in US coal prices due to rising global demand before 2008, then a rapid fall after 2008 when global demands declined [23]. Likewise, natural gas prices have fluctuated greatly since 2000 [25].

Using more renewable energy can lower the prices of and demand for natural gas and coal by increasing competition and diversifying our energy supplies. And an increased reliance on renewable energy can help protect consumers when fossil fuel prices spike. 

Reliability and resilience

 Wind and solar are less prone to large-scale failure because they are distributed and modular. Distributed systems are spread out over a large geographical area, so a severe weather event in one location will not cut off power to an entire region. Modular systems are composed of numerous individual wind turbines or solar arrays. Even if some of the equipment in the system is damaged, the rest can typically continue to operate.

For example, Hurricane Sandy damaged fossil fuel-dominated electric generation and distribution systems in New York and New Jersey and left millions of people without power. In contrast, renewable energy projects in the Northeast weathered Hurricane Sandy with minimal damage or disruption [25]. 

Water scarcity is another risk for non-renewable power plants. Coal, nuclear, and many natural gas plants depend on having sufficient water for cooling, which means that severe droughts and heat waves can put electricity generation at risk. Wind and solar photovoltaic systems do not require water to generate electricity and can operate reliably in conditions that may otherwise require closing a fossil fuel-powered plant. (For more information, see How it Works: Water for Electricity.)  

The risk of disruptive events will also increase in the future as droughts, heat waves, more intense storms, and increasingly severe wildfires become more frequent due to global warming—increasing the need for resilient, clean technologies.

Learn more:

As always, you can change any assumptions as you wish by copying/duplicating this Google Sheet.

References:

[1] Environmental Protection Agency. 2017. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015.

[2] Energy Information Agency (EIA). 2017. How much of the U.S. carbon dioxide emissions are associated with electricity generation?

[3] Intergovernmental Panel on Climate Change (IPCC). 2011. IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Prepared by Working Group III of the Intergovernmental Panel on Climate Change [O. Edenhofer, R. Pichs-Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1075 pp. (Chapter 9).

[4] Union of Concerned Scientists (UCS). 2009. Clean Power Green Jobs.

[5] National Renewable Energy Laboratory (NREL). 2012. Renewable Electricity Futures Study. Volume 1, pg. 210.

[6] Epstein, P.R.,J. J. Buonocore, K. Eckerle, M. Hendryx, B. M. Stout III, R. Heinberg, R. W. Clapp, B. May, N. L. Reinhart, M. M. Ahern, S. K. Doshi, and L. Glustrom. 2011. Full cost accounting for the life cycle of coal in “Ecological Economics Reviews.” Ann. N.Y. Acad. Sci. 1219: 73–98.

[7] Renewable Electricity Futures Study. 2012.

[8] NREL. 2016. Estimating Renewable Energy Economic Potential in the United States: Methodology and Initial Results.

[9] Renewable Electricity Futures Study. 2012.

IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Prepared by Working Group III of the Intergovernmental Panel on Climate Change. 2011.

UCS. 2009. Climate 2030: A national blueprint for a clean energy economy.

[10] American Wind Energy Association (AWEA). 2017. AWEA U.S. Wind Industry Annual Market Report: Year Ending 2016. Washington, D.C.: American Wind Energy Association.

 [11] Wiser, Ryan, and Mark Bolinger. 2017. 2016 Wind Technologies Market Report. U.S. Department of Energy.

[12] The Solar Foundation. 2017. National Solar Jobs Census 2016.

[13] Navigant Consulting. 2009. Job Creation Opportunities in Hydropower.

[14] Geothermal Energy Association. 2010. Green Jobs through Geothermal Energy.

[15] UCS. 2009. Clean Power Green Jobs.

[16] Environmental Protection Agency. 2010. Assessing the Multiple Benefits of Clean Energy: A Resource for States. Chapter 5.

[17] UCS. 2009. Clean Power Green Jobs.

[18] Deyette, J., and B. Freese. 2010. Burning coal, burning cash: Ranking the states that import the most coal. Cambridge, MA: Union of Concerned Scientists.

[20] SEIA. 2017. Solar Market Insight Report 2017 Q2.

[21] AWEA. 2017. AWEA U.S. Wind Industry Annual Market Report: Year Ending 2016. Washington, D.C.: American Wind Energy Association.

[22] UCS. 2009. Clean Power Green Jobs.

[23] UCS. 2011. A Risky Proposition: The financial hazards of new investments in coal plants.

[24] EIA. 2013. U.S. Natural Gas Wellhead Price.

[25] Unger, David J. 2012. Are renewables stormproof? Hurricane Sandy tests solar, wind. The Christian Science Monitor. November 19.

[26] Department of Energy. 2017 U.S. Energy and Employment ReportLast revised date: December 20, 2017

Curtailment Is The Easy Answer

June 15th, 2019 by Barry A.F. 

In a recent article, we found that curtailment of renewables may be cheaper than grid scale energy storage. Sometimes, the simplest solution is the best solution. However, given the complexity of electrical grids around the world, we should also look at all of the available solutions to make sure we are making the best choice for each application.

Renewable energy production not only varies from day to day, but season to season. Spring conditions often provide excellent solar generation as the sun is bright, yet AC use is low. Hot summer days, on the other hand, track well with AC usage but the afternoon duck curve comes into play, making it challenging to pair up generation directly with consumption. Wind, while forecastable with reasonable accuracy, also has great variations from day to day and season to season.

The right already weaponizes the intermittency of renewables and this will only escalate as curtailment of renewable generation enters the discussion. They will use this as yet another rallying cry against all renewables, regardless of its merit. It will be convincing to the masses because while curtailment is already in widespread use, knowledge about the cost and effectiveness of curtailment is mostly confined to industry players and very learned members of the public.

Interestingly, California is already curtailing solar generation, though it seems to be a case of solar being easier to curtail than fossil fuels or hydropower.

A Primer On Curtailment

For those who don’t know how curtailment is used today, fossil-based electricity generation must be used as soon as its generated because most grids have very little storage capacity beyond pumped hydro (which is only available in some locations). In general, natural gas can be throttled down when demand is low (older plants are the least likely to have this ability), coal is relatively difficult to throttle and nuclear is generally not throttled. In theory it is possible to throttle all energy sources, but in practice, throttling coal and nuclear are often more of a headache than they are worth so it is not commonly done.

In Australia, instead of throttling coal, they use it to heat hot water at night to help stabilize demand by creating artificial demand when generation would otherwise be curtailed. Doing this also reduces daytime demand when grid usage is highest and they struggle to meet peak power. The practice is essentially time shifting daytime loads into the night. The practice is lossy because the hot water is being generated and stored when its not really needed and it loses some heat as it waits to be used. More on this later.

Alternatives To Avoid Curtailment

So what are our other options to avoid curtailment? Battery storage is the most obvious solution. Just install enough grid scale battery storage capacity to meet demand, then size solar and wind generation to fill it. This will inevitably not track perfectly, leading to some curtailment and during the shoulder seasons, the curtailment will be higher than average. Grid scale batteries are reasonably good solutions to match up supply and demand as the prices of batteries are expected to continue falling.

Expect technological advances and that grid storage batteries will not be limited exclusively to lithium-ion chemistries, as they largely have been to date. New chemistries and energy storage techniques from flow batteries to solar thermal to molten salt to nickel iron are already meeting these needs and that is not even touching on the technological advancements we can expect from future innovations.

Stationary residential battery systems will likely become commonplace as prices drop. Tesla has done an amazing job designing the software to make their Powerwall battery work seamlessly to optimize efficiency in reducing grid loads while maximizing its utility. Home batteries also add resiliency in case of natural disasters which can be maximized by the addition smart software, like Tesla Powerwall’s Storm Watch, which actively looks for external threats to the grid and proactively stores up power if a threat is identified. These smaller batteries can also be linked together to form virtual power plants. Finally, community batteries are a very cost effective concept if they become widespread.

Adjusting the direction that of solar panels face is another viable option to tune production timing. At one point California had a $500 incentive to install solar on the west side of buildings to fight the duck curve. However, these incentives or even the addition of solar panel trackers add cost to a system, and for roof installations they are impractical. A few extra panels may cost less but only add to the curtailment problem.

Interestingly, California and other jurisdictions have existing electricity contracts to import/export power that are incompatible with the new renewable landscape. These will need to be renegotiated. On the flip side, selling extra power to neighboring states or provinces is a reasonable alternative. In fact, with some well negotiated contracts, one can virtually send power across a continent.

While it would be inefficient to directly transmit power over thousands of kilometers, if California, for example, sells its excess power for cheap to a neighboring state, that state can send its power to its neighbor and daisy chain the technique as far as needed. Since weather patterns are regional, there will be places with less renewable generation at any given time. This requires forethought and contracts built to support the new logic as well as a well-designed grid. Both are fundamental in the modeling work that has already been done to map out 100% renewable grids.

Pumped hydro storage is an option for places that have geographically-favorable terrain for hydropower generators. Not all of these locations already have the pumps required to move water back up to the top of the reservoir to store any excess power though these do exist in many locations already.

Cruachann pumped storage hydropower facility in Argyll and Bute, Scotland.

As mentioned earlier, Australia uses inflexible coal to heat hot water at night. This technique can be used elsewhere to absorb excess generation from renewables as well. If there is excess power generation during the day (from solar) or night (from wind), smart controllers can be used in homes/commercial/industrial locations to soak it up in the form of heating up water for storage in a water tank, extra cold weather heating of buildings beyond the thermostat set point (within reason), extra cooling in hot climates and so forth.

Interestingly, systems have already been developed such as the Ice Bear which freezes water at night to provide air conditioning during the day to work around peak power rates. Similar systems can be developed to store heat as well. Utilities can support the electrification of transportation and build up a new market for themselves by offering excess power for electric vehicle charging at a reduced rate. This can be automated through smart chargers or through manual triggers to let owners know they can plug in and soak it up. Utilities around the world are already starting to leverage EV chargers to absorb or shed loads to keep the grid balanced, so this is much more than just blue sky thinking.

There are also less conventional methods for storing energy that may become viable for large scale deployment in the future such as:

Climate Change Challenges

Batteries are excellent for expected demand but one challenge of designing the renewable grid of the future is meeting exceptional unexpected demand. While models typically use historical demand and weather data in designing required amounts of renewable and storage assets needed, climate change has already screwed with our weather patterns significantly. A severe heat wave or very extreme winter storm could deplete our batteries. Coupled with unexpected low generator output could lead to energy shortages as we won’t have long-term seasonal level storage if we only use batteries.

Some of the suggested options and others not yet discussed can be leveraged to handle long-term seasonal level storage of months or years.

Excess energy can be used for carbon capture. Burning natural gas or diverting power from other productive uses to sequester CO2 is ludicrous, but if you have huge amounts of excess energy being produced and the only option is to waste it, you can use it to take CO2 out of the air. Of course, it is easier to not produce that CO2 in the first place, but our emissions to date have already locked in a good amount of changed climate, so there is still a benefit to leveraging excess electricity to pull some of that carbon back out of the atmosphere.

Conclusion

In conclusion, curtailment is an inefficient use of resources and will result in us not reducing fossil fuel usage as quickly as we potentially could if renewable generation and energy storage are installed in places where they will cut the most carbon by not being curtailed. That said, some curtailment is acceptable and may even be unavoidable, but large scale curtailment should be minimized with and ultimate goal being zero curtailed electricity.

This article is a concept that can benefit from even more good energy storage ideas, so please feel free to add more ideas in the comments.