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What Will 100% Renewable Energy Look Like?

As Hawaii, California, and even some in the federal government move forward on legislation to move towards 100% renewable energy, utilities are finding paths to meet these goals, mainly focusing on solar panels, wind, and batteries for energy storage. But what exactly does 100% renewable look like, and how long will it take?

When Representative Alexandria Ocasio-Cortez and Senator Ed Markey introduced the Green New Deal, it was met with some heavy eye-rolling by certain individuals. Many saw it more as political stunt than a true path to dealing with the underlying causes of climate change. For many, the most attention-grabbing section was certainly its goal of shifting to a 100% carbon free economy after a mere decade.

While the plan is grandiose and gives a very short timetable, the general goal isn’t far-fetched. Numerous states, cities, and even utilities have committed to 100% renewable goals in the last few years, and they’re becoming more and more common.

In 2017, Hawaii became the first state to ratify a goal of 100% renewable electricity, by 2045. In December 2018, Xcel Energy – which provides electricity in 8 states in the mountain west – became the first major utility to commit to 100% carbon-free electricity by 2050. In late 2018, California also signed into law a goal of 100% clean energy –not renewable energy – by 2045. (We’ll get into the differences between clean and renewable energy in the next section.)

What does 100% renewable look like, and is it really a viable option on a large scale?

What’s Your Goal? Renewable Energy vs Clean Energy vs Carbon Free Economy


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The Green New Deal wants a carbon-free economy. Hawaii’s pledged 100% renewables. California’s pledged 100% clean energy. They might sound like synonyms, but there’s major differences among them.

First, a 100% renewable energy goal is just that. All electricity is sourced via renewable methods, typically solar, wind, and possibly water like tidal and wave energy or small hydro plants.

A 100% clean energy goal, on the other hand, broadens the scope of allowable technology. Any electricity generation that produces zero carbon is on the table, including solar and wind, but also nuclear power and fossil fuel plants with carbon capture and storage (CSS), a system in which utilities essentially capture all the carbon emissions and bury them underground so they don’t enter the atmosphere. Because the technologies allowed are more flexible, clean energy goals should be easier to meet than 100% renewable goals.

Lastly, the Green New Deal posits a 100% carbon free economy. Along with carbon-free electricity, like in the goals above, the Green New Deal also seeks to decarbonize the transportation and industrial sectors as well. Unlike the previous goals that only involve the electric sector, this far-reaching goal would require fundamental changes for every sector and every market – a much larger project.

How Does 100% Renewable Work?


Image Source: Graph from Solar Tribune


When we think about going 100% renewable, most of us probably picture fields of solar panels and wind turbines on sunny, windy days. That’s certainly part of the future, but by no means the whole picture. In reality, moving to 100% renewable requires a balance of three key actions: energy use reduction, renewable energy, and energy storage.

Reducing energy use

The first step to going 100% renewable is simply cutting out waste. There are many ways to decrease energy use. The Green New Deal includes legislation to create more stringent energy efficiency standards for buildings. The state of Hawaii already requires homes to include solar hot water heaters to pre-heat water using the sun’s abundant heat. By dropping energy needs as low as possible, you’re able to build less infrastructure, and there’s less wear-and-tear, leading to lower long-term costs.

Adding renewable energy sources

Renewable energy technology is, of course, key to building a 100% renewable electricity industry. Utilities can use utility-scale and rooftop photovoltaic solar, concentrated solar power (CSP), on- and offshore wind turbines, tidal/wave energy, and geothermal to meet energy needs.

Different renewable sources produce power at different times, a challenge known as intermittency. Solar panels, of course, produce electricity during the day. Land-based wind turbines typically produce more electricity during daylight hours. Off-shore wind produces more at night. Diversifying the technology portfolio and balancing their electricity generation is key.

Adding energy storage

Energy storage is seen as the solution to renewable energy’s intermittency problem. Lithium-ion batteries are hot commodities right now and utilities use massive banks for large-scale storage projects, but they aren’t the only options available. There’s a handful of other cheaper battery technologies as well, and utilities have a few more unusual energy storage methods at their disposal as well, like compressed air in caves that’s heated to pressure (yes, this really exists!) and pumped hydro using two reservoirs and gravity-fed turbines.

Tesla’s lithium-ion batteries, known as Powerpacks for utility-scale projects, are the most well-known energy storage on the market, and the company has installed over 1 gigawatt-hour of energy storage as of fall 2018, with another GWh in the works in the next 12 months.

In 2019, Tesla was working with California utility PG&E for a Powerpack up to 1.1 GWh, over 8x larger than their current largest project, a 129 MWh system in Australia. With PG&E’s January 2019 bankruptcy though, this project is almost certainly on hold.

A Look into the Future

In 2017, a research group from Stanford published an article in the forward-thinking journal Joule which laid out potential pathways to 100% clean economies by 2050 in 139 countries. Their study focused on the technical feasibility of such a move, creating a two-step process: 1) Electrify all industries (for example, moving all vehicles to batteries and fuel cells) and 2) Transfer all electricity production from fossil fuels to a unique mix of wind, water, and solar tailored to each country.

Looking at the world’s overall electricity demand over the next few decades, the authors propose that we could meet 2050’s estimated 20.6 terawatts of electricity demand via energy reduction and electrification’s greater efficiency than combustion (for example, electric vehicles are more energy efficient than gas-powered vehicles), onshore and offshore wind, utility-scale PV solar and CSP, residential and commercial solar, and wave/tidal energy.

Hawaii’s Plan for 100% Renewable


100% renewable energy

Image Source: CC license via Wikimedia


In 2017, Hawaii passed legislation to source all electricity from renewable sources by 2045. If we want to see what going 100% renewable looks like in the real world, we can turn to them as an example.

Thanks to their remoteness and the high cost of importing fossil fuels, Hawaii suffers from the highest electricity prices in the country, which as of November 2018 is $0.34 per kWh – 2.6x higher than the national average of $0.13 per kWh.

The state leaves Hawaii’s utilities to decide the best way to achieve this goal, though the Hawaii PUC (Public Utilities Commission) has the final say on utilities’ plans and also gives guidance on what utilities should be moving towards. Like we discussed above, the commission recommends (p.6) that utilities plan for new renewable generation, energy reduction via demand response, and energy storage:

“The PSIPs [utility action plans] are to include actionable strategies and implementation plans to expeditiously retire older, less-efficient fossil generation… increase generation flexibility, and adopt new technologies such as demand response and energy storage”

In their plan approved by the PUC in July 2017, HECO – one of three privately-owned utilities on the islands (all of which are owned by Hawaiian Electric Industries) – laid out their pathway to meet the 100% renewable goal, which included 400 MW of new renewable energy resources by 2021, continued growth of residential solar (17% of HECO’s customers have installed solar, compared to just 1% for the national average), and adding energy storage to the generation mix.

Since the plan was approved, they’ve been moving forward on these goals. In mid-2018, they sought PUC approval for two Li-ion battery storage systems totaling 120 MW and entered contract negotiations for seven solar+storage installations across three islands totaling 260 MW.

How Does 100% Renewable Affect You?

You might wonder how all this affects you. Most of us just want reliable, freely-available electricity. If it’s renewably sourced, that’s certainly a plus, but not a necessity.

That mindset though is quickly retreating, as the clean energy movement and the signs of global warming continue to stir people to, if not action, then at least acceptance. According to a 2018 poll, 74% of Americans believe worldwide temperatures are rising.

On the household level, increased utility rates for customers are always a concern, as utilities seek to update existing generation plants and build new plants, and create and implement new programs. In 2017, when utility HECO sought approval from Hawaii’s PUC for its proposed plan to 100% renewability, the PUC was worried it could increase electricity rates due to near-term capital investments and financial commitments.

The real change though, especially moving to a 100% carbon free economy, is that each business and homeowner will have to engage more deeply with their energy use. Demand response, rooftop solar, and EVs all require greater involvement from customers. Transferring to 100% clean energy isn’t a one-and-done process. It won’t be immediate, and it’ll likely take much longer than a decade. It’s a slow progression of change, brought on one project at a time.

And while electricity in the future might need a more hands-on, mindful approach than we’re used to, what we’ll get out of it – namely a cleaner, more efficient electric grid and economy – is something we’ll all benefit from down the line.

Image Source: CC license via Wikimedia

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