We.

Start with a look at why our transition to a greener future can mean dealing with the legacy of our past. Fossil fuels like oil and gas have been powering the world for decades, but they often leave behind facilities that continue to pollute long after they've been shut down. I traveled to America's forgotten oil country to meet the people sealing off our abandoned wells. On a cold day in autumn, these workers are helping clean up part of America's petroleum past. Old oil and gas wells left abandoned for generations, and they're not always where you might expect. When you picture oil country, you probably think of the oil fields down in Texas. But we are in a residential neighborhood in upstate New York. Here, just outside of Buffalo, this abandoned gas well is being sealed off in the middle of someone's front yard.

We've had some wells.

That are literally feet from a house. When they were drilled 100 to 150 years ago.

A lot of.

These houses didn't.

Exist at the time.

Over time, as areas get developed, you have structures and houses being built right up against them sometimes. It's part of the nation's fossil fuel legacy. Just a couple of hours south in Titusville, Pennsylvania, likely the first modern oil was drilled back in 1859. It sparked an oil rush across the region. By the 1880s, Pennsylvania rock oil made up more than three quarters of the global supply. But the boom eventually dried up, and now decades later, abandoned wells like this are still polluting. So this is an abandoned well. It's one of hundreds of thousands scattered across the United States, and every single one of them could still be emitting methane, a greenhouse gas several times more potent than carbon dioxide.

Up until very recently, methane emissions was not that much of a concern. It's only been recent science that has shown how damaging methane actually can be. So even trace amounts of methane that is leaking out of these wells can be pretty impactful to the climate. And so we're doing everything we can to be sure that we seal those up. Over beyond the rig here, we have a freshwater tank.

Luke Plante is the CEO of Plante & Goodwin, a third generation oil services company. And business is an overdrive. In 2021, a federal infrastructure bill set aside some $4.7 billion for capping old wells, the most ever spent on the problem. A few years ago, nobody really cared.

About these orphan wells.

Through various avenues, the government was able to come up with some money and inject that into each state to help solve this problem. But the solution, injecting concrete deep underground can be slow and sometimes dangerous.

So this well had some obstructions only 50 feet down in the well that we didn't know we were going to run into when we entered it. The challenge there is as you clean those obstructions out, there could be significant gas pressure behind them. So you always have to be mindful of well control so that you don't take a large explosion or kick up at surface.

And the scale of the problem is vast. There are more than 120,000 documented sites stretching across the United States. It's estimated the true number could be in the millions, leaking nearly 3 % of the nation's total methane emissions.

This year, we're projected to successfully decommission somewhere around 150 to 200 of these wells. But when we're talking about the problem of wells and the thousands, tens of thousands, hundreds of thousands, obviously that's not going to quite get it done. We're actively hiring more people. We are buying more equipment. We're doing everything that we can in order to ramp up quickly and address this issue.

Cleaning up the pollution of the past, creating a new green boom. Here, where the last one went bust.

The people that drilled these wells and the companies that drilled these wells haven't been in business for 50 years or 100 years in some cases. Now, it's left with what's called their the legacy wells, the legacy of 100 years of unregulated oil and gas exploration. Now we're coming back and trying to clean up and do right by the communities that were affected by it.

All right, let's talk more now about energy emissions and why cleaning them up could make a big difference. Here's the BBC's former science editor, David Shchukman.

If you want to try to limit the rise in temperatures, limit the explosion of extreme weather events that we're seeing being so destructive at the moment, one of the best things that can be done is to limit the leaking of methane into the atmosphere. The oil industry has been talking about this, has been accused for years of allowing methane to escape into the atmosphere. There are many other sources of it as well. The hope has to be that at last people start to understand that the more they can limit the venting of methane, the escape of methane from the leaky pipes, for example, the bigger the difference it'll make. It'll have a difference that's not just significant in scale, but also in speed. We really now need quick action on climate change. Curbing methane will be a great way to do that.

So what will the energy of the future look like? The good news is a lot of the technology that we need is already here. Wind and solar energy made up 12% of our global electricity supply in 2022, and that was a new record. 2023 could be even higher. That's thanks, at least in part, to solar plants built on a massive scale. Recently, Paul Carter visited the largest solar plant in the world on the edge of the Sahara Desert. This is Nor, a solar.

Power station putting Morocco at the forefront of pioneering renewable technology. This is not an ordinary solar field. Panels with over 7000 mirrors follow the sun. And I can hear lots of sounds at the moment. It's quite eerie. Is that the panel's moving? Yeah, this is movement.

Just with a small speed.

All these reflect the sun back at this dazzling monument. Two hundred and forty three meters up, this white-hot beacon can hit 1,000 degrees Celsius. A liquid salt absorbs and transports this heat, using it to produce steam and generate electricity on the ground. While solar is used across the globe, what's special here is the molten salt, which retains energy eight hours after dark.

Even with all the progress that we've made on renewables, some energy experts say we're going to need more, a lot more. One report from the International Energy Agency says the world should triple its renewable power capacity by the year 2030 as part of a plan to limit global warming to 1.5 degrees Celsius and avoid the worst effects of climate change. For more on where we're at and where we need to go when it comes to renewables, I spoke with the IAEA's Senior Energy Analyst, Hamey Bihar. Can you give us the good news on renewable energy? What are you seeing in terms of global growth?

Over the last few years, we have been seeing record-level new power plants being installed year after year. Last year there was again an important jump of 15% more capacity that's being deployed. This is great. Policymakers are introducing new policies or implementing faster their existing policies and the costs are coming down.

Now, the IAEA has released a report and it says that the world needs to triple its renewable power capacity by 2030 in order to stay on track to meet our goals in the Paris Agreement of 1.5 degrees Celsius warming. Tell me more about that tripling number and what needs to happen to achieve that goal.

We see that this tripling is ambitious but achievable, and this ambition will be defined by government's policies and how they approach and how they push this tripling capacity in the coming eight years basically. Now, it's a very short period of time. In order to solve the challenges that is upcoming, big or small, renewables can offer a solution. The government slowly discovered that it used to be climate change mitigation, then energy security coming to the picture, and show the governments that actually deploying renewables faster is a solution to energy security issues as well. In that sense, I think renewables have proven to be resilient and offering solutions to the challenges that the world is facing.

Let's talk economics, because for a long time, renewables were seen as more expensive than fossil fuels. Is that still the case?

I can give you the good news on this one, especially for solar, PV, and wind, which account for majority of this tripling growth that we need. They are in the majority of the countries, not maybe most countries in the world, they are cheaper than fossil fuel alternatives, both natural gas and coal. The cost discussion is almost over, in my opinion.

Greening the world's energy supply is obviously a big challenge. What gives you the biggest reason for optimism that we can do it in time?

The big optimism that I have, first of all, is the costs. Because if they were not economically available in our hands, the government or society will have a different view on the clean energy transition. This is an important turning point, I think, to achieve this faster expansion of renewables. In that sense, governments are still behind renewables, not providing subsidies, though. More and more, they are providing the framework, a better framework that they can operate in rather than providing them cash. That's the thing that needs to continue because renewables require a stable policy environment, which many governments today are able to provide, and it is important that they keep doing it.

Now to a city that's truly walking the walk when it comes to renewable energy. You might know Burlington, Vermont, as the home of Ben & Jerry's Ice Cream, but it's also the first US city to get 100 % of its electricity from renewable sources, and one of more than 40 cities globally. The head of the city's electric company gave me the inside scoop. I just want to start with this statistic, which is really striking. Twenty-five % of Burlington's energy came from renewable energy sources. Just a decade later, you're now at 100 % renewable energy. What changed? How did you get to 100 % renewables?

Yeah, it's a great story for Burlington. In 2004, we were 25 % renewable. The Electric Commission and the Electric Department set a goal of moving to become 100 % renewable. But over the course of that 10-year period, Burlington Electric was able to contract for different wind projects to increase its reliance on hydropower to start to add solar to its mix as well. In 2014, the last step in that process was purchase of a local hydropower dam called the Winooski one that we now own and operate. That was the last piece of the puzzle.

This is Vermont that we're talking about. So obviously the sun doesn't always shine, the wind doesn't always blow. Are there days when it's difficult to close that gap and power your city without having to resort to dirtier sources of electricity?

It's exactly right that wind and solar are really important resources, but they are variable resources. So we rely on the ability to run our woodchip plant where we can store fuel on site and dispatch it when it's needed. And we definitely rely on hydropower. Increasingly, we're going to see battery storage play an important role there as well.

You mentioned this woodchip plant, it's often called biomass. It's essentially burning wood to generate electricity. That does come with its own drawbacks, its own impacts on the environment. How do you balance that? What are the drawbacks when it comes to using biomass, which I believe is about a third of your electricity supply?

We're using local wood residue, and essentially when foresters are going out and harvesting for other higher-value operations to get wood for timber, for furniture, for construction, there's leftover wood product: tops and limbs, diseased and damaged trees. We're able to take that leftover product and use it for electricity. So that has a very different carbon profile than if somebody was going out and just clear cutting trees specifically for energy.

Converting an entire city to 100 % renewable electricity is not an easy task. How did you go about getting the community on board? What's been the reaction from citizens there in Burlington, Vermont?

So I think that it's partly that we have a committed population that supports these types of initiatives, and it's also that we're trying to do so in a way that's economically beneficial, and hopefully that's replicable for other communities as Burlington.

Is a smaller city, around 50,000 people. How can what's been done there be scaled up and applied to much larger cities in the US?

We talk with other communities, other community leaders from out of state, even sometimes internationally. We have folks who visit Burlington. And one of the things that I like to share is it's really important to start with a tangible goal. And I think every community has some renewable resources that they can utilize, some efforts that they can utilize towards energy efficiency. There are now additional communities since we became 100 % renewable that have joined us, and we hope to have many, many more.

The world continues to make progress on switching to renewable energy, but some industries face a tougher task than others. One of them is the aviation industry. Although air travel makes up around two % of the world's energy related CO2 emissions, companies like Delta Airlines say they're working hard to find ways to decarbonize. I caught up with Delta's Chief Sustainability Officer, Amelia DeLuca. Aviation is really one of the hardest industries to try to decarbonize. Why is that? Just talk us through some of the challenges that you're facing at Delta and in the industry as a whole.

Let's talk about the airline industry real quick. I think it's important to just note that we are 2-3 % of global greenhouse gas emissions today, but as a hard to decarbonize sector that's expected to grow as other industries start to move towards net zero before 2050. What makes us hard to decarbonize it's the singular fact that 90 % of our impact on the planet comes from jet fuel. Putting a battery pack on an airplane, just physics, means that isn't really doable. Our solutions aren't as straightforward as, say, the automotive industry.

What is that replacement? Is there a clear path right now to coming up with a fuel that will be a lot more sustainable than what airplanes currently use?

When we think about the future, there are lots of things we can do as a company to be more fuel-efficient. Our airplanes are obviously more fuel-efficient, but that doesn't get you to zero. The answer is essentially sustainable aviation fuel or SAF. Sustainable aviation fuel is a liquid drop in fuel. It's just like the jet fuels of today, except for instead of coming from finite resources like fossil fuels, it's coming from renewable sources. It could be bio or ag-based, which is what you're seeing today in terms of used cooking oil or potentially corn residue product. But in the future, just like other industries, it'll come from synthetic sources, but that are renewable and are infinite. Things like hydrogen and carbon in the future is what will be our fuel source.

What's the timeline we're looking at here? Because there has been some criticism of the airline industry as a whole of saying, Look, can you speed things up? It's been taking some time, right?

It's fascinating because I've seen the industry really come together with a very clear call to action. I think that's the positive is that we're very united as an airline industry that we have these net zero ambitions and we have a roadmap to get there. We know what we need to do. But the single biggest lever that we're going to have to pull is the creation of an entirely new industry, the sustainable aviation fuel. And when we just root ourselves in the number, even as Delta, the task is daunting, but we are making progress. For example, I would just call out that year over year, for the last number of years, we've increased the use of sustainable aviation fuel. That's positive, right? It's moving up every single year. But the fact of the matter is this year, we'll probably use about five million gallons of sustainable aviation fuel and that's all that we can get. That's all that we can get our hands on. And we need to get to 400 million gallons by the back half of this decade. And that's still only 10 % of a replacement for jet fuel. I think the big thing is we want to be able to decarbonize and move to Net Zero not just for the sake of our own industry, but really for the sake of the world.

The fact of the matter is we still all want to travel to see our friends, see our families. Often you have to get on an airplane to do that. What message would you give to people who feel this little bit of guilt or shame because they know that they're flying, they know that that emits CO2? What message of hope can you give for the future, for people that want to continue to be able to fly on airplanes?

I think it's important to say we know what we need to do to get to a net zero future. That's the first thing. I think the second thing is we're doing everything that we can do today to bring down our impact on the planet. And so while it may take us a little while to get to net zero, have the confidence when you go through the travel experience that you are already seeing ways that we are starting to bring down our greenhouse gas emissions to bring down our footprint from single-use plastics. A couple other things that customers aren't always going to see, but they should be aware of is how we're operating our planes today is already significantly more efficient than it was even a couple of years ago. We're changing how we land, how we navigate through airspace. We're changing the weight that we put on board through our galley carts or our servicing provisions to try to reduce the weight that's on that airplane or try to operate more efficiently. And so these are things customers you may not see when you're flying, but just know every single day we are operating more efficiently than we did the day before, and that's already starting to move us towards a better future.

As we just heard, there has been some progress on making air travel more sustainable, like this Royal Air Force flight in 2022. Now, it was the first in the UK to be powered by cooking oil. The 90-minute flight was also the first time that a military aircraft of that size flew on sustainable fuel. The RAF says waste-based fuels could lower carbon emissions by up to 80 %. Okay, now to something that may seem like science fiction, conjuring energy out of thin air. Well, two scientists have developed a device that uses a natural protein and moisture in the air to generate a small continuous electric current, and they think it could be a game-changer. I spoke to one of the scientists behind the project, electrical engineer, Jun Yang. Pulling electricity out of the sky, I mean, this is an idea that goes all the way back to Nikola Tesla in the 20th century, right? But you think that you might have figured this out.

Today in the lab, there's possibility for that. Although I think we have a way to go to scale this up from the lab prototype device to a much larger device that can be deployed in the, for example, ambient environment.

What will it take to scale that up? I understand that the current device can generate enough power to turn on one pixel of a TV screen. That's not a whole lot of electricity.

Correct. You can imagine the thin air probably cannot bolster in terms of energy density, but I think it can boaster in terms of volume because the entire Earth is covered with a very thick layer of atmospheric humidity.

If this does become successful, Professor, do you imagine this being used in our homes? Is this something that might power our refrigerator or our TV?

Why not? I think probably it could be more attractive than solar panel, because why the solar panel still competeswith space. Or actually, it can be ugly, deploying on the roof. But imagine this does not compete with any existing space because humidity is 24/7 continuous. It's day and night, it's everywhere.

And once we create energy, it's also crucial that we find ways to store it. For that, we go from air to sand and the world's first large-scale sand battery.

I'm here in the municipal swimming pool in Kankanpaa in.

Western Finland. It's a beautiful pool, very.

Barmy all year round.

But the heat that's in here comes from a rather.

Surprising source.

From sand.

The sand in question sits inside this silo in a power plant on the edge of this.

Small Finnish town.

It's the first commercial installation of a potentially important technology that works in.

A.

Surprisingly simple way. Electricity from wind or solar power is converted into heat, which warms the sand up to around 500 degrees Celsius. Crucially, the sand can keep this heat.

Without.

Loss potentially for months. And finally, if you've ever traveled on the London underground, then you know just how hot it can get down there. But what if all that hot air could be put to good use? Well, at one abandoned tube station, it's being harnessed to heat buildings up above. Jamie Moreland discovered how it works.

Everyone knows how hot the underground can get. People crowded onto trains, friction between the.

Rails and wheels.

Here, they're taking that heat and using it to warm up homes and businesses. Down there is the Northern Line, and this used to be a passenger walkway. Now, when air is pushed through from the trains, it goes up this ventilation shaft here, which used to be where the lifts were. The warm air is sucked up the ventilation shaft by a fan. And this is the top of the ventilator shaft. The air is pumped from here into these pipes above the ground. The warm air heats the water in this tank, and that hot water is pumped to more than 1,000 nearby council buildings. Such as homes, leisure centers, and moorland primary school, who knew an abandoned tube station could reduce carbon emissions and make London more self-sufficient?

And before we go, a quick reminder. If you want to get more from Future Earth delivered each week directly to your inbox, sign up for the Future Earth newsletter. In it, you'll find behind the scenes reporting from me, the week's top climate stories and insights from our entire BBC Climate Change team. I'm Carl Nasman. Thanks for watching Future Earth.