When we think about greening up the planet, solar panels and electric cars are often at the forefront of our mind. However, there’s a whole bunch of other things out there that are spewing out carbon dioxide that also need to be cleaned up. That includes leaf blowers, lawn mowers, and yes – big equipment for construction and agricultural work!
JCB manufactures diesel engines for big machines, but is now looking to switch things up for a cleaner future. To that end, the company is working on hydrogen-burning engines for its big machines.
Burning The Lightest Gas
Hydrogen can be used to produce electricity by passing it through a fuel cell, where it can then be used to power motors. Companies have explored using hydrogen in this manner to power cars and trucks. JCB initially started by looking at hydrogen fuel cells, too, but found they weren’t great at delivering the instantaneous high power needed for construction machinery. Instead, the company began exploring using hydrogen to burn in otherwise fairly conventional combustion engines. It’s a concept that other companies have explored too, with Toyota even looking into the technology with a motorsports program.
Hydrogen is useful as a fuel because its combustion is very clean. In terms of the direct products of the chemical reaction between hydrogen and oxygen, the only byproduct is water. Of course, when burning hydrogen at high temperatures in air, the reaction does cause the production of some oxides of nitrogen. Overall though, the emissions from hydrogen combustion are far cleaner than burning fossil fuels. It’s all down to the absence of carbon, which means the reaction produces zero carbon dioxide.
![](https://hackaday.com/wp-content/uploads/2022/11/JCB_-Building-a-Hydrogen-Future-3-13-screenshot-1.png?w=400)
For this reason, JCB has pursued hydrogen combustion engines as a way to cleanly power its machines. The company has developed a 4.8-liter four-cylinder hydrogen-powered engine. It’s capable of putting out the same power and torque as the company’s similarly-sized Dieselmax 448 engine, and is expected to land at the same cost, too. Plus, there’s even potential to retrofit the cleaner-burning engine to old machines.
To build the hydrogen engine, JCB started with the bottom half of the existing Dieselmax model. The sump and cylinder block are the same as the diesel-powered model, as is the cooling system. The hydrogen engine also still uses a regular variable-geometry turbo. Up top, though, the engine is quite different. There’s a new cylinder head and injection system, designed for injecting hydrogen gas instead of diesel. The engine had to be modified for spark ignition instead of compression ignition, too, as hydrogen is most suited to the former. The diesel fuel tank is similarly gone, replaced with five 1kg storage vessels for hydrogen gas made of aluminium and carbon fiber. .
Notably, hydrogen-burning combustion engine can work in largely the same way as a spark-ignition gasoline engine. Just like a gas engine can be converted to run on liquified petroleum gas, they can be converted to run on hydrogen pretty much just by changing the injectors, albeit at lower power thanks to induction inefficiencies. Designing a direct-injection engine specifically for hydrogen combustion can get around this problem though, and could theoretically produce an engine with 20% more power than a similar-sized gasoline engine. Other modifications to suit hydrogen power, like hardened valves and special spark plugs, help with longevity and to improve the quality of combustion. As for diesel engines, they’re not as simple to convert to hydrogen power, as the gaseous fuel isn’t as suitable for compression ignition. However, as JCB has demonstrated, a hydrogen engine of similar size can match the power and torque of a diesel when built properly, and can even share fundamental components.
JCB’s engine is still in the testing phase. It aims to start pre-production on the engine by the end of 2023, applying to its construction and agricultural vehicles. Meanwhile, as much as hydrogen is cleaner burning than fossil fuels, the technology does still face some hurdles to wider adoption.
Challenges
![](https://hackaday.com/wp-content/uploads/2022/11/A_FST_REFULER_HYDROGEN_6.jpg?w=400)
Hydrogen doesn’t have a viable distribution network yet, either in terms of long-distance pipelines or in terms of filling stations for consumers. To that end, JCB has developed its own mobile refuelling vehicle. For agricultural and construction operators, this fits the bill, as fuel is often taken to machines, rather than vice versa. It’s far less of an issue compared to powering road-going vehicles, which owners expect to be able to drive to a filling station wherever they are.
Producing hydrogen is also a problem. It can be produced cleanly using renewable electricity to split water into hydrogen, producing what is known as “green hydrogen.” However, much hydrogen currently on the market is instead chemically produced from natural gas, releasing harmful carbon emissions and making what is called “grey hydrogen”. Some producers split the difference, storing the carbon emissions to make what is known as “blue hydrogen.” Fundamentally, though, there simply isn’t a major renewable source of “green hydrogen” ready to power hydrogen vehicles yet. Thus, hydrogen vehicles are currently just shifting emissions to the grey hydrogen plants.
![](https://hackaday.com/wp-content/uploads/2022/11/JCBs-Hydrogen-Fuel-Cell-X-Series-Excavator-A-Zero-Emission-Industry-First-0-29-screenshot.png?w=400)
The other major problem with hydrogen combustion engines is efficiency. Hydrogen-engined vehicles have a well-to-wheel efficiency of only around 20-25%, which compares poorly to the 25-30% figure for hydrogen fuel cell vehicles. That’s largely down to the greater losses involved in internal combustion engines compared to fuel cells. However, when compared to battery vehicles, the losses are even worse, thanks to all the energy lost in refining and transporting hydrogen fuel. A comparable electric vehicle could have efficiency as high as 80-85% in comparison. In the end, a hydrogen-burning vehicle is roughly as efficient as a diesel-burning one, though with the benefit of having far cleaner emissions.
Looking Ahead
Overall, if the world is to get to a point of net zero carbon emissions, just about every fossil-fuel burning machine will need to be converted to a method of cleaner operation. JCB’s research over the last few years is pursuing exactly that goal, and should be commended.
At the same time, it’s clear that there are more hurdles to clear before the world of construction and agricultural machinery can be said to be fully clean and green. For machines that work heavy jobs for long hours, electric drive may not yet be an option. In those cases, hydrogen combustion could be a viable technology to clean them up in the meantime. However, the production and distribution of cleanly-sourced hydrogen must be there to make the pursuit worthwhile. JCB is holding up its end of the deal, and the supply of hydrogen must catch up to complete the puzzle.
The biggest problem with Hydrogen in this use case is that it’s so leaky. Even NASA struggles to design tanks and pipes that can contain the slippery stuff.
Isn’t the biggest problem hydrogen diffusing into and making metal brittle, killing the engine way sooner than a diesel would take to give out?
Probably not, as that takes time and the hydrogen isn’t in an ICE long enough before each bang.
It might if you keep the tank forever full for years cause a failure to the fuel tank, or fuel lines – but those can be engineered way over the required strength to last despite being a little brittle.
Also @Jonathan Bennett NASA is a space agency, that puts extra challenges as any solution has to be very very light as well, on the ground when you can easily overspec everything to a huge degree so it is not looking that bad as a leak rate – How fast do the petrol vapors escape through the hoses and filler cap seals for instance?
Maybe incorporate graphene into the tank and run the fuel into the omega engine.
https://youtu.be/JaP8iplOjz8
I see this comment regularly trotted when engineers talk about Hydrogen power, which I guess is better than the layperson always mentioning the Hindenburg. Turns out that only fairly high-performance steel (ie ‘High Alloy’) is susceptible (and some other less-widespread metals).
Most hard steel (HRc > 32) is affected, this needs to be (and is) addressed when selecting materials for HICEs. Hydrogen embrittlement has been observed to cause ductile fracture in valve stems. Yes… it’s not like in a Saturn V, but it’s also not a non-issue in ICEs.
Isn’t that because they store it cryogenically not under pressure?
No, hydrogen embrittlement is always a problem when dealing with pure hydrogen, whether it’s liquid or gasseous
Well, with liquid hydrogen you also have the issue of it being cold enough to condense liquid oxygen out of the atmosphere.
Which when mixed are not exactly safe.
I’ve always thought the Engine is here to stay.. It’s just the Fuel that needs to Change..
I’m thinking make the Engine a Duel Fuel.. Compressed Hydrogen or CNG.. This way it could survive Spot Shortages until the Fuel Supply and Delivery gets sorted out..
Cap
“I’m thinking make the Engine a Duel Fuel”
Interesting, having the fuels determine which one will be used.
“There can only be one!”
B^)
Beonly
=]
Give hydrogen a rest and focus on making AT SCALE a compatible synthetic or biofuel for heavy industry/aviation/shipping.
Liquid fuels are the logical choice here; far simpler, safer and efficient to transport and store.
I made a similar comment. Electric may be fine for personal transportation, but we always seem to fall into the “one size fits all” trap
One could use ammonia.
https://youtu.be/VilfJ_GYW_Q
Crops used to make biofuels displace those used for FOOD!
the real innovation would be to convert food waste into biofuel.
Let’s not forget plastics. That which cannot be reused should be recycled.
I wonder why we are not just using alcohol, especially if it was made from waste.
It would leverage existing engine designs as well as distibution.
The problem with alcohol as a fuel is that it’s only efficient to make it in very specific circumstances.
Most of the gasoline sold here in the States contains 8-10% ethanol, and maybe 1/4 of all the corn grown here is grown just for that purpose. But here the market is entirely artificial, supported by farm subsidies and usage mandates.
Growing corn for fuel actually uses a bit more energy and costs more than the gasoline it replaces. Were it not for the fact that the midwestern farming states play an outsized role in the political process here, the market would collapse overnight
In contrast, some parts of South America have a thriving ethanol fuel industry because there the feedstock is a type of sugarcane that grows like a weed, requiring very little energy to produce.
I gotta think that waste not grown specifically for the purpose is going to fall more on the corn side of the equation than the sugar cane side.
Seems like that would make an ideal component for a hybrid system.
if only food waste could be used to create it…
Instead of wasting food!
B^)
Yah the ethanol problem is that a) you wanna cheer it for being an example of a mass produced biofuel, but b) you wanna point out that it’s a boondoggle and only a fraction of the efficiency of biofuel crops that c) don’t even require the best food grade agricultural land.
Also just about every other simple alcohol is less energetically expensive to either produce or extract the water from. (Although water content could be tolerated better if it was used as a sole fuel and not mixed.)
No good way to make it at large scale that doesn’t involve wasting good farmland growing corn. Not enough waste of a material and quantity to make alcohol either. Even the current amount of alcohol produced for addition to gasoline is kind of terrible and not actually very good for the environment
Not being a chemist, but I would have thought there must be some way to create a synthetic hydrocarbon.
Hydrocarbons are not the problem, the problem is where you get them from.
Works with nitrogen (ammonia/NH3). Why this aversion to anything with a carbon atom in it?
Synthetic hydrocarbons? You mean like Ethanol? Yeah, overall efficiency of growing/harvesting/extracting/refining turns out to make worse ecologically.
Can make synthetic fuels for general use. Methane -> syngas -> methanol -> dimethyl ether -> any ‘gasoline like’ liquids you desire.
Problem is currently the methane feedstock is natural gas, and each step above is wasteful in terms of energy.
A source of the methane can from the atmosphere, by reacting the carbon dioxide with hydrogen. You just need to get the hydrogen from somewhere…
Which could be thermochemical via nuclear power, in something like a molten salt reactor than runs at 500+ deg C.
A LOT of steps there but they can all be done in a chemical plant next to a nuclear reactor. But the output is a stable fuel you can truck around in tankers and pump into cars and trucks etc.
I don’t disagree with you, but one could say that all our environmental problems would go away if we had cheap carbon-free power… but if we could only take the politics out, “a chemical plant next to a nuclear reactor” may well be a part of the solution.
The biggest problem with hydrogen – the one that always gets glossed over in discussions about how green it is – is that hydrogen is not itself a primary fuel.
You don’t *mine* hydrogen, you *make* it. And you have to make it using some other form of energy.
Yes, you can create it through electrolysis, but that requires electricity, which has to come from somewhere.
If you’ve got spare electricity that you otherwise can’t use, like a hydro dam that’s gotta flow water all night to maintain a navigable river regardless of power demand, or a nuclear plant where the incremental cost of running a third shift is minor, then yay! Clean electrolysis for you!
But most hydrogen produced in commercial quantities is made by fracturing natural gas with steam and heat. Which, of course, uses even more gas and produces lots of CO2.
So… hydrogen good.
Sometimes.
But it’s also a technology *very* susceptible to greenwashing – I’m looking at you, “Blue Hydrogen” ads – so keeping a little healthy skepticism is probably a good thing.
It is always fun hearing politicians exclaim that “hydrogen will fuel our future!”
As an engineer one has to ask, “But what fuels the creation of the hydrogen?”
Some say excess wind power, or other renewables. But the lackluster efficiency of electrolysis makes that rather inept.
Some argues that “efficiency don’t matter here, the power is wasted regardless.”
Except. There is plenty of other energy storage solutions that has far less losses and would be far more practical. Though, have stumbled over the occasional hydrogen proponent that blames these competing solutions as “inept” due to having inefficiencies…….
Exactly. The entire hydrogen push is ultimately from the gas industry. If they can get a hydrogen economy going, they know that the cheapest way to create hydrogen is from fossil fuels. Cheaper wins, every time.
There is nothing green about the hydrogen economy.
Fossil fuel companies trying to screw us? Well, now I’ve heard everything.
Hydrogen is having very lackluster energy density when one actually runs the numbers.
It might store 100 MJ/kg. But have fun trying to carry any noteworthy amount of it around.
Hydrogen at 900 bar has a density of 46.8 Kg/m^3, giving a total of about 4.68 GJ/m^3
Methane (natural-/bio-gas) is a lot easier to carry. Being some 96 kg/m^3 at 120 bar. And with 55 MJ/kg it packs a fair amount of energy at nearly 5.28 GJ/m^3.
Ethane meanwhile liquefies at about 40-45 bar depending on ambient temperature, storing about 360 kg/m^3. With an energy density of 50 MJ/kg it stores an impressive 18 GJ/m^3.
And both methane and ethane are far easier to liquefy since their boiling points are far higher than that of hydrogen. Likewise are they far less of an escape artist. So minimizing leaks is far more trivial.
Ethane is also somewhat easy to produce from methane. For an example via the Wurtz reaction. This will also have some other byproducts, like propane, butane and so forth up the chain. And this process isn’t all that uncommon for refineries to use already. Crude oil after all seldom have the right mix for current market demands, and the efficiency of this process is fairly decent.
Ethane also burns a lot more nicely than the fairly explosive hydrogen. Nor does it cause much concern for hydrogen embrittlement.
In the end.
Hydrogen as a vehicle fuel isn’t really that great.
It caries a lot of technical challenges for lackluster results.
To a degree, it feels like the market and politicians have gotten fooled. Or just straight up believe that since it can be made through electrolysis that it will therefore be the best thing since sliced bread.
Hydrogen is great as an industrial gas for various chemical reactions. But as a fuel or energy storage medium it is frankly inept.
Bio-methane is chemically identical to fossil natural gas. Therefore the problem is, how to have a 25 year bio-methane business plan that survives fossil natural gas being given away free for a couple of years to run you out of business… and other shady tricks, like fossil NG industry buying all your feedstock to stick in a landfill instead, or burn, anything so you don’t get it, then probably pointing the finger and saying “Look how these bio fuel supply surpluses are so SUPER bad for the environment, we need to bury it or burn it to get rid of it!!! Meanwhile people are starving in Africa (because we won’t let them have food and political stability, not because there isn’t any) ” and that’s probably just first page of the dirty tricks manual. Plus is easy to get the greensheep stirred up bleating burn is bad, burn is bad, whether it’s carbon negative to neutral or not.
Anyway, biofuels that don’t have expensive enough feedstocks to create a powerful lobby and PR and dirty tricks dept of their own, are fuels of the future. The future where friendly aliens turn up and beam every ounce of fossil fuel into space to save us, or where we’ve actually used every last scrap. (Alternatively they have to be so new an idea they can be patented and licensed up the wazoo and create the war chest for same. It’s not that older ideas are bad, just everyone can use them so no profit concentration.)
So if you have a large farm or small isolated country, you can probably make it work with tech level no higher than 1980 (8 bit control is just convenience feature though) coulda started on this if Axis controlled all oil fields in WWII and we’d be golden. (Didn’t work too well for them, but they didn’t possess the largest acreage for biomass, and still had to eat. Much of their synfuel tech was coal based though.)
Anyway, it’s as much about economic, fiscal and political warfare as it is coming up with crap that works.
Biogas production is already done industrially and that has been the case for a long time. And it is economically competitive against natural gas. That it hasn’t outcompeted natural gas is mainly due to demand being frankly rather big, so the additional supply doesn’t really shift the price needle much.
And currently a lot more investment is happening in the biogas sphere than before. Partly thanks to Russia’s invasion of Ukraine and the resulting stop in delivering LNG to the EU that in turn has started importing more from the rest of the world. Generally increasing natural gas prices as a result. And Biogas follows the same price since it is the same gas, just a non fossil source.
Together with a general desire to reduce the use of fossil fuels in general, then political pressure is more in favor of further expansion of biogas than against it. And then there is all the countries and especially companies desiring to be ahead of the curve and in turn happily pay extra for getting biogas.
It likewise isn’t unreasonable to expect that natural gas extraction will become restricted in the future. Especially when more biogas production has been established.
And do remember.
A fair amount of biogas is a byproduct of other processes. A common one is from sewage treatment plants, and these are quite common and handle quite a lot of biomass per day. Even at a fairly low yield it still is a lot of gas. However, the vast majority of waste water treatment plants don’t collect the methane. A fair amount of treatment plants do the opposite where they instead add oxygen to the water to discourage the production of methane from anaerobic digestion. And even a fair few that do collect the biogas opt to simply burn it.
And simply burning the gas doesn’t indicate that it weren’t profitable to sell it. Just look at oil companies. A lot of these burns their natural gas, even if it is profitable to sell it instead. But the return on investment is slower compared to investing on handling and refining of oil that constitutes a larger portion of what they have extracted from the well.
However, for a sewage treatment plant the collection of biogas can be seen as “outside the scope of work” and the surrounding bureaucratic processes can make this a slow debacle to get up and running. But this is likely to change over the coming decade as this becomes more common.
Yes, I think most success in the short term is going to be where vertically integrated opportunties exist, in organisations that create the feedstock, make the gas and can use or it have ready local market.
When I was a kid and worked on a floor full of male geeks, we had ‘biogas production wars’.
KimChi, Hard boiled eggs and cheap beer was the Tsar Bomba.
A manager cleared the building, the smell of Sulfur dioxide made him think ‘natural gas leak’ (he wasn’t wrong).
Building had no gas service.
We stopped after that.
“That’s the only time Dad’s ass prevented the release of a toxic gas!”
-Bart Simpson
Burning the natural gas instead of selling it is bad enough… but what’s REALLY bad is not extracting the helium from the natural gas first. That stuff is a non-renewable resource and when it’s gone it’s gone. Say goodbye to MRIs and a whole host of other industrial technology.
I find those company promotion video’s quite annoying. 80% of the video is just them bloating about how wonderful they think they themselves are with almost no technical details. At 04:00 there is a short snippet about some some tanker for storing hydrogen.
I do have to give them credit though for apparently getting beyond the prototype stage and having something ready for production. (according to their own words, I have not verified it)
But from what I know about hydrogen, storage is a much bigger problem then burning it.For example, space rockets would love to burn hydrogen, but there is no technology yet to store enough of the stuff on the rocket itself to reach orbit.
I don’t know much about chemistry, but converting it to a liquid fuel as bootstrap noted seems to be a more sensible option. Even adding a bit of carbon to make butane or propane out of it would make it vastly easier to store. But I don’t now how diffficult that is or what the total energy balance looks like.
> “For example, space rockets would love to burn hydrogen, but there is no technology yet to store enough of the stuff on the rocket itself to reach orbit.”
What the heck are you even talking about? What do you think they use as propellant? Gasoline?! https://en.wikipedia.org/wiki/Rocket_propellant
In few years those things will (at best!) end up in JCB’s internal museum, captioned “we tried, we really did, it’s the technology that just isn’t there yet”… just like it wasn’t there 10, 20, 30 and 40 years ago.
Burning hydrogen in an ICE gets around the enormous EV-like up-front vehicle cost because an ICE is so much cheaper than a fuel cell (or battery pack), but other than that it suffers all the usual hydrogen vehicle problems – the fuel is a nightmare to transport and store, currently there are only a handful of “hydrogen stations” in the world, the hydrogen isn’t that different in cost to traditional fossil fuels, and currently almost all of it is made from fossil fuels or produced as a fossil-fuel byproduct. The only vehicles that hydrogen could make sense for are spacecraft and large aircraft where cryogenic fuel tanks are practical and batteries aren’t.
I think the future of construction vehicle power is batteries + extension cords. Most construction vehicles spend a lot of time basically sitting in one place and moving around very little and could run on grid power similar to the largest mining equipment.
Micro nuclear looks like an option also. Power plant in a shipping container. Depending on how much power required, there’s biofuel generators in shipping containers, that run off woodchips (from land prep and clearance?) by companies such as AllPower.
Diesel engines do in fact burn hydrogen already. If you manage the particulate issues with diesel exhaust, and run on synthetic fuel, they are still a superior technology, regardless of what color the marketing guy tells you to paint the engine cover.
Why hydrogen and not Fischer-Tropsch green synthetic diesel?
Why not Butanol as a transition fuel ? Currently it is produced in low amounts because there is no interest in using it and no time has been spent on making the production more efficient. As I understand it is almost a 1 for 1 replacement for gasoline and requires little to no changes to an ICE. We to work on transition fuels and tech and take slower steps to greening up.
All grouchiness aside about actually producing hydrogen, it seems to me that it would be better to go with a hybrid setup where the engine is as minimal as possible and as efficient as possible.
A lot of the machinery is practically a hydraulic hybrid already with the motor running pumps at fixed or limited range of speed. There is not very much momentum to recover though from a bulldozer pushing earth at 3mph.
There’s a slow shift from hydraulic operation to electric, because the hydraulic system is highly inefficient – something like 20-40% at best. Most of the energy is spent on just churning oil.
Yeah! construction sites are very safe and controlled enviroments with machinery that is always in perfect working condition. Using a leaky and explosive gas sounds like a great idea,
To be fair, hydrogen floats away pretty quickly. It’s not going to pool somewhere like liquid fuel or oil. And construction sites already manage _actual explosives_ just fine – e.g blasting in mine sites, explosive fasteners etc.
High temperature chemical synthesis, what’s nice is that Gen IV and Gen V nuclear reactors should make this cheap, simple and truly green.
I work for JCB and they had the media there this morning along with Lord Bamford himself to announce the launch of the hydrogen engine.
So we have launched it…but now what? We will have engines built and sat in storage until the hydrogen can be easily sourced as a supply material.
We have been warned about how explosive hydrogen is, although we are still expected to work with it. I might be worried for nothing or it could be a disaster waiting to happen. Who knows?
I have enjoyed reading the comments and I do agree that for now, there are better alternatives out there that could be looked into. It is interesting to know that unless there is capital to be made somewhere, companies aren’t interested. And yet again, it all boils down to money and not to how we can make improvements just for the sake of the planet. Never really thought that way about it, but it definitely makes sense.
Hydrogen is safe if done correctly. It’s only dangerous in car applications because of the speed in which one is driving. Wrecks at high speeds can cause large explosions. In Large equipment, and on most construction sites you are not traveling at high speeds ever. There are safety relief valves that can be put on beyond certain pressures, and it’s safe to release into the atmosphere should something crash into it. There are also ways to build it so hydrogen is created in-vehicle. You simply pour water and an electrolytic, and it will generate hydrogen as needed so even in a high speed wreck there’s not enough of it to cause a major explosion, no more than a gas explosion generated from engine compression.
There are safer ways to implement hydrogen, and unsafe ways, we’ll need to monitor how JCB does it. If Hydrogen is in a canister ready to go then it will be more dangerous if impacted.
What you don’t want is an electric future where the batteries have to be replaced after 3 years because they won’t charge fast enough, and the replacement costs as much as the machine. I much prefer a hydrogen future.
It’s still dumb and doesn’t work right even if it’s done safely
How about just keep diesel and quit messing around
Yes. Hydrogen is stupid. Really stupid. It’s always a gimmick for green good boy PR points (this never makes sense when fully examined).
Hydrogen ICEs are the worst of several worlds, and are an option of last resort.
It takes at least 55 kWh to create 1 kg of hydrogen via electrolysis. It takes another 10 kWh or so to compress it to 700 bar, and a similar amount to liquefy it.
If you use that hydrogen in a BMW H7 (with an ICE), it gets you 25 km of range.
If you use that hydrogen in a Toyota Mirai FCV, you get 100 km of range.
If you use 65 kWh to charge a BEV, you get 300 km of range.
Leave a tank filled with hydrogen alone for 2 weeks, and it will be empty.
Construction machinery is a case where a hydrogen ICE might work. They’re run for 8 hours/day every day, so the storage issue is less important.
It’s a bit surprising JCB didn’t get the fuel cell option to work, construction machines often have highly variable load patterns so you’d expect a fuel cell backed by batteries to be viable.