Tuesday, October 16, 2018

Carbon Capture: BECCS

BECCS is an acronym for Bio Energy with Carbon Capture and Storage. It uses plant material in a pyrolysis process to produce electricity. As discussed in the earlier post about biochar, the pyrolysis process produces three outputs:

  • a carbon-rich gas called syngas which is flammable, and contains about half the energy density of natural gas.
  • the solid char, a charcoal which has a much higher concentration of carbon than the original plant material.
  • a thick tar referred to as bio-oil, which is much higher in oxygen than petroleum but otherwise similar.

BECCS is a commercial operation to pyrolyze organic material at scale, usually by growing trees specifically for the purpose.

  • generate electricity by burning the syngas
  • use the char to keep the carbon it holds sequestered for a significant length of time. Though this might involve burial deep underground, char is also useful as a soil additive and takes many years to biodegrade. We could handle a substantial amount of carbon returning to the environment at a long enough cadence.
  • the bio-oil currently has little commercial use but has great potential, as it could displace petroleum in a number of chemical processes.

Because the feedstock for BECCS is newly grown vegetative material, it is strictly carbon neutral. If the char keeps carbon out of the atmosphere for a lengthy period of time, BECCS becomes carbon negative and draws down carbon from the environment while providing revenue via power generation to fund its own operation.

BECCS gets a substantial amount of attention because it is already operating at a substantial scale, removing hundreds of kilotons of carbon dioxide from the atmosphere each year. This is a few orders of magnitude off from where we need to get, but is proof that the process works.

The existing BECCS installations capture byproducts produced in existing agricultural processes, like fermenting corn for ethanol production. An analysis of geo data in 2018 estimated that BECCS could draw down approximately 100 megatons of carbon dioxide per year by 2020 using available land area.

Thursday, October 11, 2018

Carbon Capture: Enhanced Weathering

Chemical weathering is the process by which various types of rock is broken down by exposure to water, oxygen, and/or carbon dioxide. For our purposes, the most relevant forms of weathering involve uptake of carbon dioxide. CO2 dissolved in rainwater forms carbonic acid, which is quite mild as acids go but sufficient over time to dissolve minerals from rock. Calcium and silicon exposed to carbonic acid will form HCO3 bicarbonate, and release calcium and silicates.

Occurring naturally, this chemical reaction takes place gradually over millions of years. Most of the bicarbonate thus produced eventually washes out to the ocean, where various organisms like coral pull carbon and dissolved calcium out of the water to make shells. The rest of the bicarbonate gradually settles into the deep ocean and eventually adds to the limestone at the ocean floor.

Enhanced weathering is a plan by which humans can accelerate this process, by grinding the appropriate types of rock into particles to maximize surface area and spreading them over an area to take up CO2. There are a number of options.

  • Bicarbonate, calcium, and magnesium at appropriate concentrations are beneficial to soil health, especially tropical soils which tend to be depleted in these minerals. Spreading powdered olivine over one third of tropical agricultural land could pull between 30 and 300 parts per million of carbon dioxide out of the atmosphere.
     
    There is a large range in that number because we just don't know enough about how these processes work at scale. Perhaps fortunately, we also don't have the capacity to quickly seed such a large fraction of the planet's land area. Over time, the results of the earliest years of effort can be measured to guide future plans.

  • Though tropical land is ideal, using olivine as a soil additive in agricultural land elsewhere would still have an effect.
     
    The term "electrogeochemistry" has been coined to refer to enhanced weathering done at large scale.

  • Mine tailings are the heaps of excess rock discarded from mining operations after the valuable minerals have been extracted. The tailings generally contain large amounts of the types of rock which will absorb CO2 as they weather, and in fact do rapidly form a shell of carbonate at the surface of the pile. If mining regulations are made to require the tailings be ground more finely and appropriately distributed, they can be effective in pulling carbon dioxide from the atmosphere.
     
    Mine tailings also tend to contain trace amounts of substances which can be harmful, like mercury. Processes such as those developed by Advanced Materials Processing, Inc to remove harmful substances from tailings would be necessary.

Wednesday, September 19, 2018

MacOS Preview.app has a Signature Tool

When I receive a PDF file to be signed and returned I have generally printed it out to sign and scan back in... like an animal, as it turns out. On a MacOS system there is a convenient way to add a signature to a PDF file without needing to print it, using only the Preview.app which comes with the system.

In the toolbar is a squiggly icon with a drop down menu:

Clicking it allows one to create a signature by either signing with a finger on the trackpad, or writing a signature on a piece of paper for the camera to scan in. The camera option does a good job of edge detection to extract only the writing and not shadows on the paper.

The resulting signature can then be added to the document and dragged to the right spot.

Saturday, September 15, 2018

The Arduino before the Arduino: Parallax Basic Stamp

I recently had cause to dig down through the layers of strata which have accumulated in my electronics bin. In one of the lower layers I found this bit of forgotten kit: the Parallax Basic Stamp II. This was the Arduino before there was an Arduino, a tiny microprocessor aimed at being simple for hobbyist and low-volume commercial use.

The Basic Stamp line is still sold today, though with designs developed over a decade ago. The devices have enough of a market to remain in production, but are otherwise moribund. The past tense will be used in this blog post.

The Basic Stamp line dates back to the early 1990s. The Basic Stamp II shown here was introduced in 1995. It used a PIC microcontroller, an 8 bit microprocessor line which has been used in deeply embedded applications for decades and is still developed today. The PIC family is a product from Microchip Technology, the same company which now supplies the AVR chips used in the Arduino after acquiring Atmel in 2016.

The PIC contained several KBytes of flash, which held a BASIC interpreter called PBASIC. An external EEPROM on the BS2 board contained the bytecode compiled user BASIC code. Though it may seem an odd choice now, in the early 1990s the choice of BASIC made sense: the modern Internet and the Tech industry did not exist, with the concordant increase in the number of people comfortable with developing software. BASIC could leverage familiarity with Microsoft GW-BASIC and QBASIC on the PC, as MS-DOS and Windows computers of this time period all shipped with BASIC. Additionally, Parallax could tap into the experience of the hobbyist community from the Apple II and Atari/Commodore/etc.


' PBASIC code for the Basic Stamp
LED         PIN 5
Button      PIN 6    ' the BS2 had 16 pins
ButtonVal   VAR Bit  ' space is precious, 1 *bit* storage
LedDuration CON 500  ' a constant

' Init code
OUTPUT LED
INPUT  Button

DO
 ButtonVal = Button                 ' Read button input pin
 FREQOUT LED,LedDuration,ButtonVal  ' PWM output to flicker LED
 PAUSE 200                          ' in milliseconds
LOOP

PBASIC supported a single thread of operation, the BASIC Stamp supported neither interrupts nor threads. Applications needing these functions would generally use a PIC chip without the BASIC interpreter on top. Later Stamp versions added a limited ability to poll pins in between each BASIC statement and take action. This seemed aimed at industrial control users of the stamps, for example Disney used BASIC Stamps in several theme park rides designed during this time frame.

A key piece of the Arduino and Raspberry Pi ecosystems is the variety of expansion kits, or "shields," which connect to the microprocessor to add capabilities and interface with the external world. The ecosystem of the BASIC Stamp was much more limited, suppliers like Adafruit were not in evidence because the low volume PCB design and contract manufacturing industry mostly didn't exist. Parallax produced some interesting kits of its own like an early autonomous wheeled robot. For the most part though, hobbyists of this era had to be comfortable with wire-wrapping.

Saturday, September 8, 2018

code.earth hackathon notes

Project Drawdown is a comprehensive plan proposed to reverse global warming. The project researchers analyzed and ranked scenarios according to the potential reduction in carbon levels, and analyzed the costs.

Project Drawdown will continue the analysis work, but is moving into an additional advocacy and empowerment role of showing governments, organizations, and individuals that global warming can be mitigated and providing detailed guidance on strategies which can work. The audience for the project's work is expanding.

This places new demands on the tools. The tooling needs to be more accessible to people in different roles, and provide multiple user interfaces tailored to different purposes. For example, the view provided to policymakers would be more top-level, showing costs and impacts, while the view for researchers would allow comparisons by varying the underlying data.

The code.earth hackathon in San Francisco September 5-7, 2018 implemented a first step in this, starting to move the modeling implementation from Microsoft Excel into a web-hosted Python process with Excel providing the data source and presentation of the results. This will separate the model implementation from user interface, making it easier to have multiple presentations tailored for different audiences. It will still be possible to get the results into Excel for further analysis, but web-based interfaces can reach much wider audiences able to act on the results.

I was at the hackathon, working on an end-to-end test for the new backend, and plan to continue working on the project for a while. Global warming is the biggest challenge of our age. We have to start treating it as such.