Many investors flocked back to cryptocurrencies during the past year as lower interest rates made speculative investments more attractive again. Earlier this month, I said the two big blue-chip cryptocurrencies -- Bitcoin (BTC 0.29%) and Ethereum (ETH 5.46%) -- were still great places to park $1,000 for a few decades.

But today, I'll take a look at three riskier cryptocurrencies -- Solana (SOL 2.83%), Cardano (ADA 5.41%), and XRP (XRP 3.09%) -- that could also have a bright future. While they might be a bit riskier than Bitcoin or Etherereum, they might be worth a more modest $500 investment.

A visualization of a blockchain.

Image source: Getty Images.

Solana

Solana's blockchain blends together the energy-efficient proof-of-stake (PoS) consensus mechanism used by Ethereum with its own proof-of-history (PoH) mechanism. That combination gives it a theoretical top speed of 65,000 transactions per second (TPS), compared to Ethereum's theoretical maximum speed of just 30 TPS. In real world transactions, which are limited by network congestion and other factors, Solana has a daily average speed of over 1,400 TPS -- compared to Ethereum's average speed of 19 TPS.

As a PoS blockchain, Solana supports the development of decentralized apps (dApps) and other crypto assets through its smart contracts. Since it's faster than Ethereum and other PoS blockchains, it's becoming a popular platform for building decentralized finance (DeFi) apps and non-fungible tokens (NFTs). Visa, Shopify, and other companies have also integrated Solana Pay (its peer-to-peer payment protocol for accepting stablecoins, Solana, and other Solana-based tokens) into their own digital ecosystems.

Solana is an inflationary token with no maximum supply, so it can't be valued by its scarcity like Bitcoin. But the growth of its ecosystem could gradually boost its value. Artemis Analytics estimates that Solana only serves about 1.5 million daily active users (DAUs) today, but VanEck thinks it could eventually rise to more than 100 million DAUs in the next five years in a bull case scenario. We should take that rosy outlook with a grain of salt, but Solana could still have plenty of room to grow.

Cardano

Cardano, which was created by Ethereum co-founder Charles Hoskinson, is another PoS blockchain that supports the development of decentralized apps. Like Solana, Cardano is faster than Ethereum with a daily average speed of about 250 TPS. By deploying its new "hydra heads," which process some of its transactions off-chain to alleviate the congestion on its main blockchain, it aims to achieve average speeds more than 1,000 TPS.

The deployment of those heads could make Cardano a more popular platform for the development of DeFi, gaming, and enterprise apps. Its new Mithril protocol, which aggregates all of the data across its blockchain into a single compressed index -- should further improve its accessibility for users and developers. It also recently enabled the transfer of Bitcoin assets on its own blockchain, and that upgrade could draw more Bitcoin-backed stablecoins to its ecosystem and support the growth of its DeFi apps.

Cardano is an inflationary token, but its speed and recent upgrades could make it a more attractive platform for developers. Assuming that happens, its price might stabilize and rise over the next few decades as it catches up to blue-chip cryptos like Bitcoin and Ethereum.

XRP

XRP is a cryptocurrency created by the founders of the fintech company Ripple Labs. Its entire supply of 100 billion tokens was mined before its launch in 2012, and Ripple sold those tokens to fund its own expansion. Those sales caught the attention of the Securities and Exchange Commission (SEC), which sued Ripple for allegedly selling unregistered securities. Those lawsuits dragged on until last year, when a court slapped Ripple with a lighter-than-expected fine and ruled that XRP wasn't an unlicensed security when sold to individual investors.

That mostly favorable ruling drew back a stampede of bulls. XRP was relisted on the major crypto exchanges, Grayscale relaunched its XRP Trust as a closed-end fund (CEF), and several crypto firms submitted their applications for XRP exchange-traded funds (ETFs). But looking beyond that near-term boost, XRP still has other irons in the fire.

Ripple is promoting the usage of XRP as a bridge currency to speed up foreign currency transactions (by temporarily converting both currencies into XRP) at lower fees. It also launched pilot programs with several central banks to use XRP to bridge the liquidity between their national central bank digital currencies (CBDCs), and it recently applied for a U.S. banking license, which would enable it to integrate XRP into more cross-border transfers. To make it more relevant with developers, it's been adding support for lightweight smart contracts (mainly used for payments instead of apps) to its blockchain. The rapid expansion of that ecosystem could drive XRP's price higher during the next few decades.