Accelerators, Explained: What They Do, Who They Help, and Why Climate Is the Next Frontier

How can founders compress months of progress into weeks, benefitting along the way from exposure to mentors, networks, and capital?

Accelerators like pioneer Y Combinator are now embedded across the UK, especially in university- and corporate-backed hubs. They boost fundraising, credibility, and partnership access for startups while helping them to align investors and industry.

As sector-specific models grow, sustainability-focused accelerators are turning climate intent into measurable impact by introducing startups to real-world pilots, impact assessment, and strategic partners.This article breaks down what accelerators are, how they help founders and investors, and where sustainability fits in. 

What are accelerators?

Accelerators are structured and selective programmes designed to help startups scale quickly. The programmes typically run for a fixed period, often three to six months, combining mentorship, workshops, network access and, in many cases, capital, culminating in a demo day or strategic pilot. They’re sometimes conflated with incubators, which are longer-running and more flexible, providing space, community and light-touch support at the ‘still-an-idea’ stage.

In the UK, the landscape has expanded rapidly. The Centre for Entrepreneurs estimates there are now more than 700 programmes supporting around 19,600 firms each year, including 269 run by universities. Attendance has surged too, rising by an average of 78% per year since 2014.

There’s strong evidence this support delivers results. Beauhurst finds that startups which go through accelerators raise, on average, 44% more capital and achieve valuations 75% higher than comparable companies that don’t.

When Y Combinator (YC) launched in 2005, and provided seed funding to a crop of software startups, it popularised a model that has reshaped the evolution of innovation. 

The concept was simple. They would bring early-stage founders together, surround them with mentors and investors, and apply an intense, time-boxed programme that compresses years of trial-and-error into a few focused months. They have since funded 5000 startups with a combined valuation of $800bn. Alumni include Airbnb, a home rental platform now worth $76bn, Stripe a fintech offering payment processing now worth $91bn, and Doordash  a food and grocery delivery company valued at $111bn. 

“Y Combinator pioneered the accelerator model and set the entire industry in motion,” says Paul Finch, Co-Founder of Growth Studio, a leading accelerator in the UK. YC showed investors they could meet cohorts that were both product and business trained, and it showed founders the power of fast paced growth, peer learning, and investor connections.

How accelerators support founders

Early-stage founders often prioritise funding, but it’s only one element in building a successful company. Accelerators can prove vital in expanding skillset, building partnerships, and getting investment-ready. 

Many teams enter with vision but gaps in experience; accelerators can close those gaps by building practical skills across fundraising, go-to-market, leadership and execution.“They give founders the entrepreneurial, business, and soft skills they need to grow and scale,” says Finch of Growth Studio. 

Early-stage teams often have deep functional expertise in engineering, science, product development or marketing, but an investable company requires competence across finance, hiring, operations and go-to-market as well. 

Finch didn’t set out to run an accelerator. “We were the UK’s first growth-hacking agency,” he recalls, “but startups kept turning up with existential problems. They couldn’t articulate what they did or who their market was. They weren’t investable. We ended up working on foundations rather than growth hacking.” Growth Studio found they could “move a business three months in the time it would otherwise take 12 to 24.”

Edward Harris, CEO of Ligo Biosciences, which uses deep learning to design novel enzymes, dropped out of Oxford University after receiving an offer from Y Combinator.  “YC was the first investor to take us seriously. They took a bet on us extremely early and taught us to think bigger, back ourselves, and brought us to San Francisco,” he says. Ligo Biosciences has since received millions in early stage funding. He believes this level of growth would have been unachievable without the intense programme his team went through at YC.

Beyond capital and coaching, accelerators create direct pathways into industries, connecting startups with partners, investors, and mentors who can accelerate commercial traction. Growth Studio’s latest Breakout Beauty programme is focused on beauty and has partnered with retailer Boots, TikTok Shop, the British Beauty Council, leading beauty founders, and investor Venrex. Outcomes for startups includes prizes worth an estimates £250k, a Boots listing, and expert advice, support, and guidance from the likes of Trinny Woodall of Trinny London, and Mitchell Halliday who founded Made by Mitchell. As Woodall says, “Over the last nearly ten years, I have built Trinny London and understand the determination it takes to build a successful brand and I can't wait to share my insights with the Breakout Beauty founders”.

The community that founders build during an accelerator is often the most valuable part of the experience. Starting a business is not only demanding but can also be isolating, and connecting with others on a similar journey provides both vital support and a sense of belonging. Research shows that 76% of founders report experiencing loneliness, and an overwhelming 93% exhibit signs of mental strain. For founders, this trusted network of peers can be continually relied on for support across all aspects of growth.

In Finch’s view, the intangible community may matter more than any other component. “When you get a cohort that gels, they outperform every single metric,” he explains. “They look out for each other, open doors, and give honest feedback. It’s a micro-community, but a really strong one.” 

“Beyond structured support, they offer peer-to-peer challenge, a sense of momentum, and the space to test and validate ideas,” says Cathal Hughes, ClimateTech Manager at Undaunted. 

The benefits of accelerators extend beyond the individual founders and the startups. They provide investors with a de-risked pipeline, lending them confidence that teams have been trained in pitch craft and product validation, pre-filtered by domain experts. Corporates gain curated innovation as accelerators, broker pilots, offer supply-chain upgrades and support with clearer diligence and delivery support. 

Wider innovation ecosystems also gain from the presence of accelerators. Universities are increasingly bringing their research into the wider world through accelerator programmes circulating knowledge, standards, and talent. By 2028 it is estimated that 27,000 startups will be established in higher education institutions. This is seen to continue beyond these institutions and into the wider economy. Research by Kings College London found that 64,384 people were employed by start-ups that emerged from universities in the 2022-23 academic year, marking a 177% increase over the last decade. 

In the UK, universities have become central to this startup growth landscape. Their role extends beyond hosting programmes to providing labs, workspace, translational expertise, and a steady pipeline of spinouts. For example, seaweed-based packaging startup Notpla  progressed through Imperial College London’s Greenhouse accelerator in 2017 and later won the £1m Earthshot Prize. 

When to join and how to pick

The right time to join an accelerator varies between founder and business. The greatest value typically comes once a company has moved beyond the idea stage and can show early progress with its technology, business model, or intellectual property. Since most programmes are highly intensive, having at least one committed co-founder can also be an advantage.

The timing differs by industry, but clear signals often include approaching a milestone such as raising a seed round, securing pilot projects, or acquiring new customers. At these points, an accelerator can provide a focused, structured pathway to reach the next stage with targeted support.

Selecting the right accelerator depends less on prestige and more on fit. Strong outcomes arise when programme focus, partners, and structure align with a startup’s stage and ambitions. Indicators such as a proven alumni network, successful exits, and industry credibility can help gauge whether a programme is likely to deliver.

An honest assessment of a company’s goals, challenges, and priorities is essential. From there, founders can shortlist programmes whose outcomes and networks match those objectives.

Why accelerators matter for sustainability

Startups with a climate or sustainability focus may experience additional layers of complexity in their growth. Many climatetech solutions are developing first-of-a-kind technology that requires dedicated physical development sites, longer project timelines, and the added challenge of navigating regulatory hurdles and intellectual property considerations.

“Climatetech brings distinctive challenges,” says Undaunted’s Hughes. “A climate-focused accelerator must stay agile, evolving to support founders in emerging or undefined markets while helping them balance mission with commercial reality”. 

Other programmes are evolving accordingly. For example, Climate KIC, Europe’s leading climate innovation agency takes the classic accelerator model and tailors it to the additional requirements of sustainability. They support founders on how to report their sustainability merits, “what’s unique about our program is that every startup completes a climate impact assessment—a light life cycle analysis that tracks emissions from raw materials through production and delivery. This helps founders identify where they can avoid the most emissions and compare their product against industry standards, even before they have a viable product”, explains Climate KIC.

Corporate-backed programmes are also supporting this early stage innovation. The Amazon Sustainability Accelerator, delivered with EIT Climate-KIC and Growth Studio, is equity-free and blends a 10-week curriculum with grants, AWS (Amazon Web Service) credits and sector mentors. The 2025 Climate Tech Cohort has been announced and includes Vuala, an “artificial stomach” that digests food waste into clean biogas and hydrogen. Mhor Energy, a rechargeable liquid flow battery that stores electricity for 20–25 years, and Greyparrot, an AI vision system that identifies 110+ waste materials to enable precision recycling. The attraction for founders is the prospect of tangible commercial pathways and operational validation.  

“Accelerators give access to a lot of experts that startups wouldn’t otherwise have,” Finch adds, such as investors, delivery specialists and, crucially, corporate partners. Done well, that access turns into commercial partnership. Finch says, “We try to work out the best mutual outcome and then bring that together in a way that has longer-term sustainable commercial impact.”

Accelerators serve as a bridge between climate tech startups developing first-of-a-kind technologies and the expertise, resources, and networks needed to turn those ideas into viable businesses.

The UK’s accelerator landscape today

A decade ago, nesta, a UK innovation agency, counted 205 incubators and 163 accelerators across the UK. As of 2023, the Centre for Entrepreneurs estimates more than 700 such programmes and roughly 19,600 firms supported annually, a near doubling since 2017. The offer has also diversified corporations that now run their own accelerators, universities have innovation hubs, and specialist verticals from fintech to climatetech are common.

When they work well, accelerators do more than provide capital or coaching. They compress years of learning into months, open trusted networks, and create the momentum startups need to reach the next stage. Some of the most valuable outcomes are intangible mindset shifts, long-term relationships, and insights that only show their full worth later.

In sustainability especially, the model is evolving. Today’s accelerators not only convene mentors, peers, and partners, but also embed impact measurement, align startups with emerging policy, and broker the partnerships required to bring complex hardware and infrastructure into the world. In doing so, they are becoming essential bridges between ambitious climate innovation and the markets, investors, and ecosystems that can make it scale.