Heimdal (YC S21) builds the world’s cheapest direct air capture plant

https://www.fastcompany.com/90750797/a-startup-in-hawaii-just-launched-the-worlds-first-ocean-assisted-carbon-removal-plant

by aerosmile • 4 years ago

25 16 4 years ago

fastcompany.com

erikmillar7• 4 years ago

Hi everyone, I know you guys enjoy the technical details so I’ve added a short rundown:

Heimdal is opening its first pilot facility in Kohala, HI in partnership with a solar powered desalination facility, Terraformation. Utilizing spent brine from active desalination plants allows us to synergistically leverage existing infrastructure, however our technology is equally viable in an independent setting. In our process, brine undergoes bipolar membrane electrodialysis (BPMED) to produce NaOH (aq), H2(g), O2(g), and HCl (aq). The hydroxide is distributed into the ocean for alkalinity. Byproducts can be sold as carbon neutral or negative commodities. Our process is filed with the US PTO and the UK Patent Office.

The Heimdal system runs entirely on renewable energy so there are next to no carbon costs of power. We expect our pilot facility in Kohala, HI to generate 100kg/day of sodium hydroxide (8% NaOH, 1250 L/day). Bipolar Membrane Electrodialysis (BPMED) produces an acid and base from a neutral salt feed stream using an electric potential and selective ion membranes. Equation 1 shows the overall reaction of BPMED using purified seawater.

𝐍𝐚𝐂𝐥+𝐇𝟐𝐎 →𝐇𝐂𝐥+𝐍𝐚𝐎𝐇 Equation 1

In our system, negatively charged membranes (Cation Exchange Membrane (CEM)) facilitate the flow of sodium ions and positively charged Anion Exchange Membranes (AEM) allow for chloride transport. Bipolar membranes (BPM) contain a catalyst sandwiched between a CEM and AEM. Water splitting occurs at the BPM junction where a catalyst assists in the reaction and ions are transported through the AEM or CEM. Ion flow through the system is also facilitated by an applied voltage which accelerates hydroxide flow toward the positively charged anode and proton flow towards negatively charged cathodes.

In the acid channel, H+ generated from BPM and Cl- transported across the AEM combine to form HCl. In the base channel, OH- ions and Na+ ions combine to form NaOH. The acid or base is recirculated through the system to maintain a steady pH and increase efficiency. Flow of NaOH around the anode and cathode aid in the production of H2 and O2 gas at the cathode and anode sites. The half reaction at the anode and cathode are displayed in Equation 2 and Equation 3.

𝟒 𝐎𝐇−→ 𝐎𝟐(𝐠)+𝟐𝐇𝟐𝐎+𝟒𝒆− Equation 2

𝟐 𝐇𝟐𝐎+𝟐 𝒆−→ 𝟐𝐇𝟐+𝟐 𝐎𝐇− Equation 3

The input of alkalinity will be monitored by pH and conductivity of the base feed as it enters the ocean. As the feed reacts with the ocean carbonate system, quantification of NaOH will be intangible. Based on Equation 1, HCl and NaOH are produced in a 1:1 fashion so the HCl produced and bottled on site can physically verify the amount of NaOH added to the ocean for alkalinity. We propose a mechanism for verification of alkalinity enhancement whereby a third party can physically verify the quantity of HCl produced and, by extension, the amount of atmospheric CO2 that must have been captured with the corresponding hydroxide. Sodium hydroxide and magnesium hydroxide will be readily dissolved in surface seawater, but mineral carbonates will likely be stored in the deep ocean since dissolution is unfavorable in surface waters. Ultimately these minerals will uptake CO2, but this proposal focuses on hydroxide as a catalyst for direct air capture of carbon dioxide. The stoichiometry of CO2 uptake is described by:

𝐍𝐚𝐎𝐇+𝐂𝐎𝟐 ⇋𝐍𝐚++𝐇𝐂𝐎𝟑− Equation 4

𝐌𝐠(𝐎𝐇)𝟐+𝟐𝐂𝐎𝟐 ⇋𝐌𝐠𝟐++𝟐𝐇𝐂𝐎𝟑− Equation 5

𝐂𝐚𝐂𝐎𝟑+𝐂𝐎𝟐+𝐇𝟐𝐎 ⇋𝐂𝐚𝟐++𝟐𝐇𝐂𝐎𝟑− Equation 6

If we produce 100 kg/day (0.1 t/day) NaOH, we will have 2.5 kmol/day.

𝟏𝟎𝟎 𝐤𝐠 𝐍𝐚𝐎𝐇𝐝𝐚𝐲≈𝟐.𝟓𝐤𝐦𝐨𝐥 𝐍𝐚𝐎𝐇𝐝𝐚𝐲 Equation 7

Assuming a 1:1 reaction with CO2:OH- estimates a maximum of 110 kg/day (~0.11 t/day) CO2 uptake.

𝟐.𝟓𝐤𝐦𝐨𝐥 𝐂𝐎𝟐𝐝𝐚𝐲𝐂𝐎𝟐≈𝟏𝟏𝟎𝐤𝐠 𝐂𝐎𝟐𝐝𝐚𝐲 Equation 8

Hydroxide in seawater will ultimately result in a decrease in free protons and uptake in CO2 since it is a strong base. Nevertheless, it is unlikely that system occurs at 100% efficiency, so these numbers are the upper limit for CO2 capture in the current proposal. We assume a modest 90% efficiency to account for natural ocean-mixing effects.

𝟎.𝟗∗𝟐.𝟓𝐤𝐦𝐨𝐥 𝐎𝐇−𝐝𝐚𝐲=𝟐.𝟐𝟓 𝐤𝐦𝐨𝐥 𝐂𝐎𝟐𝐝𝐚𝐲≈ 𝟗𝟗𝐤𝐠 𝐂𝐎𝟐𝐝𝐚𝐲 Equation 9

Based on 365 operating days per year and 90% CO2 draw-down efficiency, we expect to capture 37 tCO2 in the first year. Although this is a fractional percentage of global emissions, it is a great start and expanding production can be done quicker than other DAC companies because we do not have to transport or store captured CO2.

aerosmile• 4 years ago

It's not every day that you come across a company like this. You really have to give it to YC for supporting some of the most ambitious ideas that are not even within its wheelhouse. It's one thing to back an early quantum computing company like Rigetti - I would imagine that Sam Altman and other partners at the time knew a thing or two about that field. But a DAC plant? How do you fact check that in a 10 minute interview?

Another notable YC investment that I always admired was Immunity Project (an attempt to make a free HIV vaccine) - https://www.ycombinator.com/companies/immunity-project.

erikmillar7• 4 years ago

Thanks for the kind words!

hn_neverguess• 4 years ago

Based on 365 operating days per year and 90% CO2 draw-down efficiency, we expect to capture 37 tCO2 in the first year.

I wonder what the business model here looks like. I suppose you could try to get government to provide tax incentives for donations?

erikmillar7• 4 years ago

The business model is a combination of governments and corporations. As of now, it is overwhelmingly corporations, but this is due to shift very soon.

uranium• 4 years ago

Multiple countries have tax incentives for carbon reductions already, such as the 45Q credit in the USA. Companies can outsource their reductions to CCS companies such as Heimdal. See e.g. https://www.cnet.com/news/google-facebook-stripe-have-a-925m...

[Disclosure: I've invested in Heimdal.]

erikmillar7• 4 years ago

Exactly, and I'm sure these incentives will start to increase in scale as the world sees the impact climate change will have on the wider economy.

version_five• 4 years ago

Personally, I favor a model of direct government spending for CO2 capture (along with emissions regulations where appropriate). Carbon pricing ends up being either a tax or an opportunity for gaming or partisanship, and just adds needless complexity everywhere.

If we can move climate change from a political tool to a concrete technological problem, government can address it directly, the same as other infrastructure, and pay operators like this on a tonnage basis to extract carbon.

erikmillar7• 4 years ago

I agree that in principle it sounds good. The one issue I pick up on here is the old 'tragedy of the commons' - some countries are just not going to want to pay for it, meaning that other countries will be hugely economically impacted by this. As far as I can see, the only way to make this enforceable for the entire planet is for the largest consumer economies (US&EU) to include a carbon boarder tax where emissions can't be outsourced to other countries.

cjbenedikt3• 4 years ago

How much CO2 is released by building the plant and it's materials and how long will it take to recover that? Honest wuesy as none of the various DAC companies offer any numbers on that subject.

erikmillar7• 4 years ago

Good question. This all depends on the scope of emissions you are looking at - only our emissions or also the emissions of the companies who manufactured various components for us. However, either way, our next plant will be capturing far more co2 than emitted during manufacture.

cjbenedikt3• 4 years ago

Of course, including the CO2 released by the companies manufacturing the components. After all, CO2 release should be fully accounted for. Capturing "far more" - how much exactly is it then?

fernandoalmansa• 4 years ago

What do you foresee the biggest hurdles being, be it logisitcal, technical or manufacturing, that you will have to overcome in order to reach the milestone of capturing 5 million tons of C02 per year in 3 years time?

erikmillar7• 4 years ago

The market is already starting to look a lot like the early stages of the EV market where demand even still drastically outweighs supply - the supply of high quality carbon credits is currently minuscule. So scaling manufacturing is definitely the priority for us. The key part of this is definitely hiring.

merlinnn• 4 years ago

The article says you sell hydrochloric acid as a byproduct:

[Heimdal] uses electricity to rearrange molecules in the water, removing acid. It can then sell the acid it removes, which ends up in the form of hydrochloric acid.

What are the other costs/revenue streams are hidden in here? Are there ways to capitalize the waste carbonate instead of depositing it back in the ocean?

cjbenedikt3• 4 years ago

Another question is regarding the HCI. You say "...so the HCl produced and bottled on site can physically verify the amount of NaOH added to the ocean for alkalinity." What happens to the bottled HCI afterwards?

Heimdal (YC S21) builds the world’s cheapest direct air capture plant

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