By Charles F. Kutscher, University of Colorado BoulderJeffrey Logan University of Colorado Boulder
James Hansen, a scientist from the University of Wisconsin, testified before Congress that carbon dioxide emitted by burning fossil fuels was causing dangerously high temperatures. There were scientific meetings, numerous reports were written, and pledges made by the nation. But fossil fuels were so cheap that little was done to reduce carbon emission.
Around 2009 saw the first wind turbines and solar photovoltaic cells become affordable enough to compete in the electricity markets. More installations resulted in more “learning curve” cost reductions – the decrease in cost with every doubling of deployment. Since 2009, the prices of wind and solar power have decreased by an astonishing 72% and 90%, respectively, and they are now the cheapest electricity sources – although some challenges still exist.
The planet is facing increasing heat waves, droughts, wildfires, and storms. A solution was found to the climate crisis: Transform the electric grid to carbon free wind and solar, and convert all other fossil fuel users in transportation, industry, and buildings to electricity.
This is the direction the U.S. is going. According to BloombergNEF data early projections show that the world just completed a record-breaking year of renewable electricity growth. This was after a record 33.500 megawatts in solar and wind power installed in the U.S. for 2020. Even faster growth is expected ahead, especially given the Biden administration’s plans to tap high-value offshore wind resources. But will it be enough?
The Biden administration’s goal is to have a carbon emissions-free grid by 2035. According to a recent study, the U.S. must nearly triple its 2020 growth rate in order to have the grid 80% powered with clean energy by 2030. (Although this may sound daunting, China has reportedly installed 120,000 megawatts in wind and solar power in 2020.
This transition begins with a fundamental change in the electric grid.
Three ways to bring wind & solar into the grid
Our grid, now aging, is hailed as the greatest invention of 20th century. It was built on fundamental concepts that made sense at its time. The original foundation was a combination of “base load” coal plants that operated 24 hours a day and large-scale hydropower.
These were added to in 1958 by nuclear power plants. They have been almost continuously operating since then to repay their large capital investment. Solar and wind, unlike coal and nuclear are not fixed. They only provide power when there is sun or wind.
It takes a new way to think about how to transform to a 21st-century grid that is more dependent on variable resources. New sources of flexibility – the ability to keep supply and demand in balance over all time scales – are essential to enable this transition.
There are three options to address the variability in wind and solar energy. You can use storage, deploy generation in a coordinated manner across a large area of the country, and manage electricity demand to better match supply. All these are sources of flexibility.
Today, lithium-ion battery storage is the most popular. They are now much cheaper and new storage technologies have been developed.
It is particularly valuable to have expanded transmission. Even though the Northeast is experiencing peak demand for electricity in the early evenings, there is still sunlight in the West. The large wind resources in the middle of the country can send electricity towards both coasts with more transmission. Transmission studies have shown that stronger interconnections among the country’s three power grids are highly beneficial.
A big part of cleaning up the grid is making buildings more efficient and controlling their consumption. 74% of the electricity used by buildings in the United States comes from them. Interconnected devices and equipment with smart meters can reduce and reshape a building’s power use.
Innovative solutions that make 100% clean electricity possible
Many analysts believe that the U.S. can operate a power grid with 80%- 90% clean electricity at a cost-effective and reliable rate. However, decarbonizing the remaining 10% to 20% of the grid will prove to be more difficult. While short-duration storage, lasting four hours or less, is becoming ubiquitous, we will likely need to provide power during some periods when wind and solar resources are at low levels (what the Germans call dunkelflaute, or “dark doldrums”). Although an expanded national transmission system will be helpful, it will likely still require some long-duration storage.
Many options are being explored, including green hydrogen and alternative battery technologies.
Flow batteries are one of the promising technologies that we are studying at the University of Colorado’s Renewable and Sustainable Energy Institute. In a typical design liquid electrolyte flows between storage tanks separated by membranes. You can scale the tanks to fit your storage needs.
Green hydrogen is a storage option that can be used for very long periods. It is made by splitting water molecules using an electrolyzer that uses renewable electricity. The hydrogen can be stored underground or in above-ground tanks. It can then be burned in combustion turbines, or converted back into electricity in fuel cells. Green hydrogen is very expensive, but it is expected to become more affordable with the decrease in cost of electrolyzers.
There are also new market design, business and grid operator models emerging. For example, homeowners can purchase solar electricity from community solar gardens even if their roofs are not suitable. Microgrids, which produce electricity locally and can operate even if the grid is down, are another popular business model. Microgrids that are clean and powered by renewable energy or batteries can be power from renewable energy.
Innovative market designs include time of use rates that encourage electricity usage, such as charging electric vehicles when renewable electricity is abundant. To provide a smoother supply, the expanded balancing area coordination draws upon variable solar and wind resources from a wider region. Advanced forecasting of wind, solar and other factors improve grid operations. This helps to reduce wasted power and reduce the need to have expensive standby reserves. Dynamic line rating allows grid operators transmit more electricity via existing lines when weather conditions are favorable.
Energy efficiency can be transformed across the economy by paying more attention to it. This will reduce costs and improve reliability.
The transition to renewables can be made easier by nuclear power, which is almost carbon-free. New nuclear plants in America are expensive to build, take long construction times, and can prove too costly for firms to use.
Our view is that the urgency of climate changes demands that we make every effort to address it. While a 2035 emission goal is important, it is equally important to determine the U.S.’s emissions reduction path in order to achieve that goal. The No. The No. 1 goal is to reduce carbon dioxide and other greenhouse gas emissions to the atmosphere. The world already has the tools necessary to make the grid carbon-free at 80% to 90%. Experts are looking into a variety of promising options to achieve the remaining 10% to 20%.
About the Authors
Charles F. Kutscher, Fellow and Senior Research Associate, Renewable & Sustainable Energy Institute, University of Colorado Boulder and Jeffrey Logan, Associate Director of Energy Policy and Analysis, Renewable & Sustainable Energy Institute, University of Colorado Boulder
This article was republished by The Conversation under a Creative Commons licence. Read the original article.